WO2013052508A1 - Compounds and compositions for modulating melanogenesis and pigmentation activities - Google Patents

Compounds and compositions for modulating melanogenesis and pigmentation activities Download PDF

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Publication number
WO2013052508A1
WO2013052508A1 PCT/US2012/058496 US2012058496W WO2013052508A1 WO 2013052508 A1 WO2013052508 A1 WO 2013052508A1 US 2012058496 W US2012058496 W US 2012058496W WO 2013052508 A1 WO2013052508 A1 WO 2013052508A1
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alkyl
optionally substituted
compound
aryl
heterocyclyl
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PCT/US2012/058496
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French (fr)
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David William Carey Hunt
Geoffrey C. Winters
Timothy Scott Daynard
Huijun Jiang
Joyce Wu
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Dermira (Canada), Inc.
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Publication of WO2013052508A1 publication Critical patent/WO2013052508A1/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D231/00—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings
    • C07D231/02—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings not condensed with other rings
    • C07D231/10—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
    • C07D231/14—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D231/38—Nitrogen atoms
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P17/00—Drugs for dermatological disorders
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D409/00—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms
    • C07D409/02—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms containing two hetero rings
    • C07D409/04—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms containing two hetero rings directly linked by a ring-member-to-ring-member bond

Definitions

  • This disclosure is generally related to compounds and pharmaceutical compositions that modulate melanogenesis and use of such compounds for treating or preventing skin pigmentation disorders as well as addressing cosmetic needs for tanning.
  • melanin is the major body pigment and the primary determinate of human skin color. In most tissues, melanocytes produce melanin within melanosomes by converting tyrosine to various forms of melanin. The melanin-containing
  • melanosomes are transported to the periphery of the melanocytes, which have a dendritic morphology, before being transferred to epidermal keratinocytes.
  • UV-induced melanogenesis is skin's major defense against further UV damage. More specifically, melanin pigmentation protects against UV damage by absorbing UV photons and UV-generated free radicals before they can react with DNA and other critical cellular components.
  • UV light can result in an increased risk of skin cancer and skin damage (e.g., premature aging and wrinkles).
  • melanogenesis are of medical interest for protecting skin from photodamage without UV exposure or the risk of skin cancer.
  • the benefit can be extended to addressing certain cosmetic needs for tanning, especially sunless tanning.
  • Skin pigmentation disorders include, for example, hyper-pigmentation and hypo-pigmentation.
  • Hyper-pigmentation can be associated with inflammatory responses, such as in keloid scars, or with local abnormal melanocyte function, as in dysplastic nevi or malignant melanoma. The counterpart to this condition is known as hypo-pigmentation, when there is a reduction or absence of pigmentation.
  • hypo- pigmentation is represented by albinism, an inherited condition where there is a complete absence of skin pigment due to absence or defect in an enzyme involved in the production of melanin.
  • Another form of hypo-pigmentation is leukoderma characterized by light patches on the skin.
  • pharmaceutical agents that stimulate the production of melanin could be effective therapy for skin pigmentation disorders that are associated with defective or absent melanocytes.
  • a variety of agents are known to affect melanogenesis in primary melanocytes and/or melanoma cells in vitro. These include prostaglandins (PG), endothelin-1 , psoralens with UVA light (PUVA), dimethylsulfoxide (DMSO), L-tyrosine, L-Dopa, lysosomotropic agents, diacylglycerols, thymidine dinucleotides, DNA fragments, a-melanocyte-stimulating hormone (MSH) analogs, 3-isobutyl-1- methylxanthine (IBMX), forskolin, FK506 (Tacrolimus), nitric oxide donors, and bicyclic monoterpene (BMT) diols.
  • PG prostaglandins
  • PUVA psoralens with UVA light
  • DMSO dimethylsulfoxide
  • L-Dopa L-tyrosine
  • Some of these agents have also been shown to increase pigmentation when applied topically onto mouse and/or human skin. For example, repeat topical application of forskolin onto mouse ears stimulated skin pigmentation. D'Orazio et al. Nature 443:340-344 (2006).
  • n 0, 1 , or 2;
  • Ri is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
  • R 2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
  • R-i and R 2 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
  • R 3 is alkyl, alkenyl, aralkyl or aryl
  • R 4 is alkyl, alkenyl, aralkyl or aryl
  • R 3 and R 4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
  • R 6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl
  • R 7 is hydrogen or alkyl
  • R 6 and R 7 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl, and
  • each R 8 is the same or different and independently alkyl, halo, haloalkyl, aralkyl, heterocyclylalkyl, nitro, cyano, -C(0)R 6 , -C(0)OR 6 , -S(0) 2 -N(R 6 )R 7 ,
  • a further embodiment describes a pharmaceutical composition
  • a pharmaceutical composition comprising a pharmaceutical effective amount of a compound of Formula (la), or a pharmaceutically acceptable salt thereof, and a pharmaceutical acceptable excipient.
  • the pharmaceutical composition is a dermatological composition.
  • a further embodiment provides a method of stimulating melanogenesis in a mammal in need thereof, the method comprising: administering to the mammal a of Formula (I):
  • n 0, 1 , 2, or 3;
  • Ri is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
  • R 2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
  • R-i and R 2 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
  • R 3 is alkyl, alkenyl, aralkyl or aryl;
  • R 4 is alkyl, alkenyl, aralkyl or aryl
  • R 3 and R 4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
  • each R 5 is the same or different and independently alkyl, halo, haloalkyl, aralkyl, heterocyclylalkyl, nitro, cyano, -C(0)R 6 , -C(0)OR 6 , -S(0) 2 -N(R 6 )R 7 ,
  • R 6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl
  • R 7 is hydrogen or alkyl
  • R 6 and R 7 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl.
  • the method of stimulating melanogenesis in a mammal in need thereof administering to the mammal a pharmaceutically effective amount of a compound of Formula (la):
  • n 0, 1 , or 2;
  • Ri is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
  • R 2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
  • Ri and R 2 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
  • R 3 is alkyl, alkenyl, aralkyl or aryl
  • R 4 is alkyl, alkenyl, aralkyl or aryl
  • R 3 and R 4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
  • R 6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl
  • R 7 is hydrogen or alkyl
  • R 6 and R 7 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl, and
  • each R 8 is the same or different and independently alkyl, halo, haloalkyl, aralkyl, heterocyclylalkyl, nitro, cyano, -C(0)R 6 , -C(0)OR 6 , -S(0) 2 -N(R 6 )R 7 ,
  • the mammal has a pigmentation disorder.
  • the mammal's pigmentation disorder is vitiligo or leukoderma.
  • the mammal's pigmentation disorder is characterized by inadequate or absent melanocytes.
  • stimulating melanogenesis includes tanning.
  • the mammal has normal pigmentation and is in need of tanning in the absence of UV exposure.
  • a further embodiment provides a method of restoring pigmentation in a mammal having a pigmentation disorder, wherein the method comprises administering to the mammal of a compound of Formulae (I):
  • n 0, 1 , 2, or 3;
  • Ri is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
  • R 2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
  • Ri and R 2 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
  • R 3 is alkyl, alkenyl, aralkyl or aryl
  • R 4 is alkyl, alkenyl, aralkyl or aryl; or R 3 and R 4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
  • each R 5 is the same or different and independently alkyl, halo, haloalkyl, aralkyl, heterocyclylalkyl, nitro, cyano, -C(0)R 6 , -C(0)OR 6 , -S(0) 2 -N(R 6 )R 7 ,
  • R 6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl
  • R 7 is hydrogen or alkyl
  • R 6 and R 7 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl.
  • the compound is of Formula (la):
  • Yet a further embodiment provides a method for treating porphyria comprising: topically administering a therapeutically effective amount of a compound of formula (I) or (la) to a subject in need thereof.
  • Yet a further embodiment provides a method for treating solar urticaria comprising: topically administering a therapeutically effective amount of a compound of formula (I) or (la) to a subject in need thereof.
  • Yet a further embodiment provides a method for treating light patches on mammalian skin comprising: topically administering a therapeutically effective amount of a compound of formula (I) or (la).
  • the light patches are results of pigmentation disorders such as leukoderma or vitiligo.
  • Another embodiment provides a method for restoring hair color by topically administering a therapeutically effective amount of a compound of formula (I) or (la) to the scalp of a subject in need thereof.
  • Yet a further embodiment provides a method for treating a degenerative neurological disorder by locally or systemically administering a pharmaceutical composition comprising a compound of formula (I) or (la) in an amount effective in stimulating neuromelanin synthesis.
  • the degenerative neurological disorder is Parkinson's disease.
  • Yet a further embodiment provides a method for treating hearing disorder by administering a compound of formula (I) or (la) intra-aurally or systemically, wherein the hearing disorders is characterized by melanocyte insufficiency in the inner ear.
  • Figure 1 shows comparative effects of forskolin, FK506 and Compound A on melanin production in human melanocytes.
  • Cells cultured for 72 h with the test compounds were assessed for melanin levels by (A) cell pellet appearance in human epidermal melanocytes;light-pigmented (HEMn-LP) cells; or (B) cell lysate melanin levels in in human epidermal melanocytes;dark-pigmented (HEMn-DP) cells.
  • Relative melanin levels are presented as a percentage (%) of the assay result obtained for cells maintained in parallel in the absence of added stimulus. Each symbol indicates the result obtained in an independent experiment. Horizontal bars denote the average of these multiple determinations.
  • Figure 2 shows the melanin levels in drug-treated melanoma cells.
  • Mouse B16-F10 (A), human G361 (B), and human Mel-Ho (C) were treated with FK506 (20 ⁇ ), or Compound A (5 ⁇ ) for 24 hours or 48 hours.
  • Cells were harvested and lysed followed by assays to determine tyrosinase activity and melanin levels.
  • Cells treated with DMSO were served as negative controls.
  • the data shown in (A) and (B) are averages of melanin levels from at least 2 repeated experiments.
  • Figure 3 shows that Compound A was capable of stimulating tyrosinase activity in HEMn-DP, HEMn-LP and HEMa-LP.
  • Melanocytes were cultured for 72 h with different concentrations of Compound A and cell extracts subsequently prepared for tyrosinase activity determinations. Results are given as a percentage (%) of the assay result obtained for untreated control cells. Symbols indicate the result from each independent experiment. Horizontal bars denote the overall average of these determinations.
  • Figure 4 shows the tyrosinase activities in drug-treated cells.
  • B16-F10 (A), G361 (B), and Mel-Ho (C) were treated with FK506 (20 ⁇ ), or Compound A (5 ⁇ ) for 24 hours or 48 hours.
  • Cells were harvested and lysed followed by assays to determine tyrosinase activity and melanin levels.
  • Cells treated with DMSO served as negative controls.
  • the data shown in (A) and (B) are averages of tyrosinase activity from at least 2 repeated experiments.
  • Figure 5 shows that an extended culture of HEMn-LP widens the melanogenesis-stimulating concentration range of Compound A.
  • Cells were cultured for 6 days in 75 cm 2 flasks with test compounds as indicated and subsequently assessed for tyrosinase activity, melanin levels and cell pellet appearance.
  • Figure 6 shows the cell morphologies of melanoma cells treated with Compound A.
  • Mouse B16-F10 (A), human G361 (B), and human Mel-Ho (C) melanoma cells were treated with Compound A for 24 or 48 h.
  • DMSO (0.1 %) was used as a negative control.
  • Pictures were taken to show cell morphological changes induced by Compound A. Pictures shown were representatives from at least two experiments.
  • Figure 7 shows the dendrite counts in B16-F10 Cells.
  • B16-F10 cells were treated with DMSO (0.1 %), FK506 (25 ⁇ ), or Compound A (5 ⁇ ) for 24 hours. Fifty cells for each treatment group were sampled. The number of cells with certain numbers of dendrites was counted. The graph shown is the average of dendrite counts from two repeated experiments.
  • Figure 8 shows that Compound A increases human neonatal melanocyte dendrite numbers and dendrite branching.
  • HEMn-DP A-D
  • HEMn-LP E-G
  • Compound A was added at 5 ⁇ while forskolin and FK506 were present at 20 ⁇ and 25 ⁇ , respectively.
  • B, E mean primary dendrite numbers
  • C, F the proportion of cells with 2-3, 4-7 or ⁇ 8 dendrites per cell
  • D, G The percentage of cells exhibiting branched dendrites was also determined (D, G). Cells not exposed to the test compounds served as controls.
  • Figure 9 shows the expression levels of the melanogenesis-regulating factors tyrosinase, microphthalmia-associated transcription factor (MITF), tyrosinase- related protein-1 (TRP1 ), and TRP2 in drug-treated cells.
  • Mouse B16-F10 melanoma cells (A) and human G361 melanoma cells (B) were treated with forskolin (20 ⁇ ), FK506 (20 ⁇ ), or Compound A (5 ⁇ ) for 24 or 48 hours.
  • Cell lysates were prepared followed by western blotting to examine the protein levels of tyrosinase, MITF, TRP1 , and TRP2. Data shown are representative of experiments repeated 3 times.
  • Figure 10 shows the effect of Compound A on viability of HEMn-LP in vitro.
  • Cell viability was assessed by the colorimetric MTS assay. Results are given as a percentage (%) of the assay determination obtained for untreated cells maintained in parallel. Mean values with standard deviations are shown. Similar effects were observed in two other experiments performed.
  • Figures 1 1A-1 1 C show the effects of Compounds A-F on melanogenesis-related parameters.
  • B16-F10 cells were treated with forskolin (25 ⁇ ), FK506 (20 ⁇ ), Compound A (5 ⁇ ), Compound B (10 ⁇ ), Compound C (10 ⁇ ), Compound D (5 ⁇ ), Compound E (1 ⁇ ), or Compound F (1 ⁇ ) were administered to the B16-F10 cells for 24 h or 48 h.
  • Dendrite counting (A) assays for tyrosinase activity and melanin levels (B), as well as the expression levels of tyrosinase and MITF (C) were examined in drug treated cells.
  • DMSO was used as a negative control.
  • pigmentation-enhancing agents have the potential to reduce both photodamage and skin cancer incidence as well as restore pigment in conditions such as vitiligo.
  • compounds which stimulate multiple aspects of the pigmentation machinery including MITF activation/expression, tyrosinase
  • C 7 -Ci 2 alkyl describes an alkyl group, as defined below, having a total of 7 to 12 carbon atoms
  • C 4 -Ci 2 cycloalkylalkyl describes a cycloalkylalkyl group, as defined below, having a total of 4 to 12 carbon atoms.
  • the total number of carbons in the shorthand notation does not include carbons that may exist in substituents of the group described.
  • Amino refers to the -NH 2 radical.
  • Haldroxy refers to the -OH radical.
  • Niro refers to the -N0 2 radical.
  • Trifluoromethyl refers to the -CF 3 radical.
  • Alkyl refers to a straight or branched hydrocarbon chain radical consisting solely of carbon and hydrogen atoms, containing no unsaturation, having from one to twelve carbon atoms, preferably one to eight carbon atoms or one to six carbon atoms, and which is attached to the rest of the molecule by a single bond, e.g., methyl, ethyl, n-propyl, 1 -methylethyl (/so-propyl), n-butyl, n-pentyl, 1 , 1 -dimethylethyl (f-butyl), 3-methylhexyl, 2-methylhexyl, and the like.
  • an alkyl group may be unsubstituted or substituted by one of the following groups: alkyl, alkenyl, halo, haloalkenyl, cyano, nitro, aryl, cycloalkyl, heterocyclyl, heteroaryl, oxo,
  • an alkyl group may be unsubstituted or substituted by one of the following groups: alkyl, alkenyl, halo, haloalkenyl, cyano, nitro, aryl, cycloalkyl, heterocyclyl, heteroaryl, oxo,
  • Alkylene or "alkylene chain” refers to a straight or branched divalent hydrocarbon chain linking the rest of the molecule to a radical group, consisting solely of carbon and hydrogen, containing no unsaturation and having from one to twelve carbon atoms, e.g., methylene, ethylene, propylene, n-butylene, and the like.
  • the alkylene chain is attached to the rest of the molecule through a single bond and to the radical group through a single bond.
  • the points of attachment of the alkylene chain to the rest of the molecule and to the radical group can be through one carbon or any two carbons within the chain.
  • an alkylene chain may be optionally substituted by one of the following groups: alkyl, alkenyl, halo, haloalkenyl, cyano, nitro, aryl, cycloalkyl, heterocyclyl, heteroaryl, oxo, trimethylsilanyl, -OR 14 , -OC(0)-R 14 , -N(R 14 ) 2 , -C(0)R 14 , -C(0)OR 14 , -C(0)N(R 14 ) 2 , -N(R 1 4 )C(0)OR 16 , -N(R 14 )C(0)R 16 , -N(R 14 )S(0) t R 16 (where t is 1 to 2), -S(0) t OR 16 (where t is 1 to 2), -S(0)pR 16 (where p is 0 to 2), and -S(0) t N(R 14 ) 2 (where t is 1 to 2) where each R 14 is
  • Aryl refers to a hydrocarbon ring system radical comprising hydrogen, 6 to 18 carbon atoms and at least one aromatic ring.
  • the aryl radical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may included fused or bridged ring systems.
  • Aryl radicals include, but are not limited to, aryl radicals derived from aceanthrylene, acenaphthylene, acephenanthrylene, anthracene, azulene, benzene, chrysene, fluoranthene, fluorene, as-indacene, s-indacene, indane, indene, naphthalene, phenalene, phenanthrene, pleiadene, pyrene, and triphenylene.
  • aryl or the prefix “ar-” (such as in “aralkyi”) is meant to include aryl radicals optionally substituted by one or more substituents independently selected from the group consisting of alkyl, alkenyl, halo, haloalkyi, haloalkenyl, cyano, nitro, aryl, aralkyi, heteroaryl,
  • Alkyi refers to a radical of the formula -R b -R c where R b is an alkylene chain as defined above and R c is one or more aryl radicals as defined above, for example, benzyl, diphenylmethyl and the like.
  • the alkylene chain part of the aralkyi radical may be optionally substituted as described above for an alkylene chain.
  • the aryl part of the aralkyi radical may be optionally substituted as described above for an aryl group.
  • Cycloalkyl refers to a stable non-aromatic monocyclic or polycyclic hydrocarbon radical consisting solely of carbon and hydrogen atoms, which may include fused or bridged ring systems, having from three to fifteen carbon atoms, preferably having from three to ten carbon atoms, and which is saturated or unsaturated and attached to the rest of the molecule by a single bond.
  • Monocyclic radicals include, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.
  • Polycyclic radicals include, for example, adamantyl, norbornyl, decalinyl, and the like.
  • cycloalkyi is meant to include cycloalkyi radicals which are optionally substituted by one or more substituents independently selected from the group consisting of alkyl, alkenyl, halo, haloalkyi, haloalkenyl, cyano, nitro, oxo, aryl, aralkyi, cycloalkyi, cycloalkylalkyi, heterocyclyl, heterocyclylalkyi, heteroaryl, heteroarylalkyl, -R 15 -OR 14 , -R 15 -OC(0)-R 14 , -R 15 -N(R 14 ) 2 , -R 15 -C(0)R 14 , -R 15 -C(0)OR 14 , -R 15 -C(0)N(R 14 ) 2 , -R 15 -N(R 14 )C(0)OR 16 , -R 15 -N(R 14 )C(0)OR 16 , -R 15 -N(R
  • Halo refers to bromo, chloro, fluoro or iodo.
  • Haloalkyi refers to an alkyl radical, as defined above, that is substituted by one or more halo radicals, as defined above, e.g., trifluoromethyl, difluoromethyl, trichloromethyl, 2,2,2-trifluoroethyl, 1 -fluoromethyl-2-fluoroethyl, 3-bromo-2-fluoropropyl, 1 -bromomethyl-2-bromoethyl, and the like.
  • the alkyl part of the haloalkyi radical may be optionally substituted as defined above for an alkyl group.
  • Hydroxyalkyl refers to an alkyl radical, as defined above, that is substituted by one or more hydroxy radicals (-OH), e.g., hydroxymethyl, 2- hydroxyethyl, etc.
  • -OH hydroxy radicals
  • the alkyl part of the hydroxyalkyl radical may be optionally substituted as defined above for an alkyl group.
  • Heterocyclyl refers to a stable 3- to 18-membered non-aromatic ring radical which consists of two to twelve carbon atoms and from one to six heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur.
  • the heterocyclyl radical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may include fused or bridged ring systems; and the nitrogen, carbon or sulfur atoms in the heterocyclyl radical may be optionally oxidized; the nitrogen atom may be optionally quaternized; and the heterocyclyl radical may be partially or fully saturated.
  • Examples of such heterocyclyl radicals include, but are not limited to, dioxolanyl, thienyl[1 ,3]dithianyl,
  • decahydroisoquinolyl imidazolinyl, imidazolidinyl, isothiazolidinyl, isoxazolidinyl, morpholinyl, octahydroindolyl, octahydroisoindolyl, 2-oxo-1 ,3-dioxol-4yl,
  • heterocyclyl is meant to include heterocyclyl radicals as defined above which are optionally substituted by one or more substituents selected from the group consisting of alkyl, alkenyl, halo, haloalkyl, haloalkenyl, cyano, oxo, thioxo, nitro, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl,
  • heterocyclylalkyl heteroaryl
  • each R 14 is independently hydrogen, alkyl, alkenyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl; each R 15 is independently a direct bond or a straight or branched alkylene or alkenylene chain; and each R 16 is alkyl, alkenyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl,
  • heterocyclyl heterocyclyl
  • heterocyclylalkyl heteroaryl or heteroarylalkyl.
  • /V-heterocyclyl refers to a heterocyclyl radical as defined above containing at least one nitrogen and where the point of attachment of the heterocyclyl radical to the rest of the molecule is through a nitrogen atom in the heterocyclyl radical.
  • An /V-heterocyclyl radical may be optionally substituted as described above for heterocyclyl radicals.
  • Heterocyclylalkyi refers to a radical of the formula -R b h where R is an alkylene chain as defined above and R h is a heterocyclyl radical as defined above, and if the heterocyclyl is a nitrogen-containing heterocyclyl, the heterocyclyl may be attached to the alkylene chain at the nitrogen atom.
  • the alkylene chain of the heterocyclylalkyi radical may be optionally substituted as defined above for an alkylene chain.
  • the heterocyclyl part of the heterocyclylalkyi radical may be optionally substituted as defined above for a heterocyclyl group.
  • Heteroaryl refers to a 5- to 14-membered ring system radical comprising hydrogen atoms, one to thirteen carbon atoms, one to six heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur, and at least one aromatic ring.
  • the heteroaryl radical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may include fused or bridged ring systems; and the nitrogen, carbon or sulfur atoms in the heteroaryl radical may be optionally oxidized; the nitrogen atom may be optionally quaternized.
  • Examples include, but are not limited to, azepinyl, acridinyl, benzimidazolyl, benzthiazolyl, benzindolyl, benzodioxolyl, benzofuranyl, benzooxazolyl, benzothiazolyl, benzothiadiazolyl, benzo[£>][1 ,4]dioxepinyl, 1 ,4-benzodioxanyl, benzonaphthofuranyl, benzoxazolyl, benzodioxolyl, benzodioxinyl, benzopyranyl, benzopyranonyl, benzofuranyl, benzofuranonyl, benzothienyl (benzothiophenyl), benzotriazolyl, benzo[4,6]imidazo[1 ,2-a]pyridinyl, carbazolyl, cinnolinyl, dibenzofuranyl,
  • 1-oxidopyrimidinyl 1-oxidopyrazinyl, 1-oxidopyridazinyl, 1-phenyl-1 H-pyrrolyl, phenazinyl, phenothiazinyl, phenoxazinyl, phthalazinyl, pteridinyl, purinyl, pyrrolyl, pyrazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrrolyl, quinazolinyl,
  • quinoxalinyl quinolinyl, quinuclidinyl
  • isoquinolinyl tetrahydroquinolinyl
  • thiazolyl thiadiazolyl
  • triazolyl tetrazolyl
  • triazinyl thiophenyl (i.e. thienyl).
  • heteroaryl is meant to include heteroaryl radicals as defined above which are optionally substituted by one or more substituents selected from the group consisting of alkyl, alkenyl, alkoxy, halo, haloalkyi, haloalkenyl, cyano, oxo, thioxo, nitro, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl,
  • heterocyclyl heterocyclyl
  • heterocyclylalkyl heteroaryl or heteroarylalkyl.
  • V-heteroaryl refers to a heteroaryl radical as defined above containing at least one nitrogen and where the point of attachment of the heteroaryl radical to the rest of the molecule is through a nitrogen atom in the heteroaryl radical.
  • An N- heteroaryl radical may be optionally substituted as described above for heteroaryl radicals.
  • Heteroarylalkyl refers to a radical of the formula -R b R, where R b is an alkylene chain as defined above and R, is a heteroaryl radical as defined above.
  • the heteroaryl part of the heteroarylalkyl radical may be optionally substituted as defined above for a heteroaryl group.
  • the alkylene chain part of the heteroarylalkyl radical may be optionally substituted as defined above for an alkylene chain.
  • Melanogenesis refers to the process of producing melanin. On mammalian skin, melanogenesis leads to a long-lasting tan. There are both basal and activated levels of melanogenesis; in general, lighter-skinned people have low basal levels of melanogenesis. As discussed in more detail herein, various embodiments of the present disclosure provide method of stimulating or activating melanogenesis in a mammal in need thereof by administering a compound of Formulae (I) or (la).
  • Stimulated or activated melanogenesis can restore pigmentation in skin afflicted with pigmentation disorders (as defined herein) or can afford long-lasting tan without the risk of UV exposure.
  • Pigmentation disorders or conditions includes disorders involving excessive, inadequate or absent pigmentation in mammalian skin.
  • the pigmentation disorder or condition that is treated by the claimed compounds or composition are typically disorders of the pigment-producing cells (melanocytes) themselves, which may be reduced in number, absent, hyperactive, inactive or commonly with regional localization.
  • pigmentation disorders include, without limitation, vitiligo and leukoderma.
  • melanocytes in localized areas are either dead or non-functioning, resulting in patches of non-pigmented skin.
  • Restore pigmentation refers to increasing the amount of pigmentation on skin afflicted with any of the pigmentation disorders or conditions, as defined herein.
  • skin pigmentation under treatment may increase in the non-pigmented patches of skin.
  • pigmentation may or may not be restored to the full extent of pigmentation as that of the normal skin surrounding the patches.
  • Dermatologically acceptable excipient includes without limitation any adjuvant, carrier, vehicle, excipient, glidant, sweetening agent, diluent, preservative, dye/colorant, flavor enhancer, surfactant, wetting agent, dispersing agent, suspending agent, stabilizer, isotonic agent, solvent, or emulsifier, including those approved by the United States Food and Drug Administration as being acceptable for dermatological use on humans or domestic animals, or which are known, or are suitable for use in dermatological compositions.
  • Poration enhancers refers to substances that promote the diffusion of the therapeutic drugs (e.g., the pyrazole compounds described herein) through the skin barrier. As is known, the skin
  • stratum corneum provides a physical barrier to the harmful effects of the external environment. In doing so, it also interferes with the absorption or transdermal delivery of topical therapeutic drugs. They typically act to reduce the impedance or resistance of the skin to allow improved permeation of the therapeutic drugs.
  • substances which would perturb the normal structure of the stratum corneum are capable of disrupting the intercellular lipid organization, thus reducing its effectiveness as a barrier. These substances could include any lipid material which would partition into the stratum corneum lipids causing a direct effect or any material which would affect the proteins and cause an indirect perturbation of the lipid structure.
  • solvents such as ethanol, can remove lipids from the stratum corneum, thus destroying its lipid organization and disrupting its barrier function.
  • penetration enhancers or barrier function disrupters include, but are not limited to, alcohol enhancers, such as alkanols with one to sixteen carbons, benzyl alcohol, butylene glycol, diethylene glycol, glycofurol, glycerides, glycerin, glycerol, phenethyl alcohol, polypropylene glycol, polyvinyl alcohol, and phenol; amide enhancers, such as /V-butyl-/V-dodecylacetamide, crotamiton, N,N- dimethylformamide, /V,/V-dimethylacetamide, /V-methyl formamide, and urea; amino acids, such as L-a-amino acids and water soluble proteins; azone and azone-like compounds, such as azacycloalkanes; essential oils, such as almond oil, amyl butyrate, apricot kernel oil, avocado oil, camphor, castor oil, 1-carvone, coconut oil,
  • Dermatologically effective amount refers to that amount of an active ingredient which, when administered dermatologically (i.e., systemically or locally, including, for example, topically, intradermally, intravenously, orally or by use of an implant) to a mammal (e.g., mammalian skin), is sufficient to effect the desired treatment, as defined below, of the disorder or condition of interest in the human.
  • the amount of an active ingredient which constitutes a "dermatologically effective amount” will vary depending on the active ingredient, the disorder or condition and its severity, and the age of the human to be treated, but can be determined routinely by one of ordinary skill in the art having regard to his own knowledge and to this disclosure.
  • Solid compound and “stable structure” are meant to indicate a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture, and formulation into an efficacious therapeutic agent.
  • “Mammal” includes humans as well as animals.
  • Optional or “optionally” means that the subsequently described event of circumstances may or may not occur, and that the description includes instances where said event or circumstance occurs and instances in which it does not.
  • optionally substituted aryl means that the aryl radical may or may not be substituted and that the description includes both substituted aryl radicals and aryl radicals having no substitution.
  • substituents on the functional group are also “optionally substituted” and so on, for the purposes of this invention, such iterations are limited to five, preferably such iterations are limited to two.
  • “Pharmaceutically acceptable carrier, diluent or excipient” includes without limitation any adjuvant, carrier, excipient, glidant, sweetening agent, diluent, preservative, dye/colorant, flavor enhancer, surfactant, wetting agent, dispersing agent, suspending agent, stabilizer, isotonic agent, solvent, or emulsifier which has been approved by the United States Food and Drug Administration as being acceptable for use in humans or domestic animals.
  • “Pharmaceutically acceptable salt” includes both acid and base addition salts.
  • “Pharmaceutically acceptable acid addition salt” refers to those salts which retain the biological effectiveness and properties of the free bases, which are not biologically or otherwise undesirable, and which are formed with inorganic acids such as, but are not limited to, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like, and organic acids such as, but not limited to, acetic acid, 2,2-dichloroacetic acid, adipic acid, alginic acid, ascorbic acid, aspartic acid, benzenesulfonic acid, benzoic acid, 4-acetamidobenzoic acid, camphoric acid, camphor-10-sulfonic acid, capric acid, caproic acid, caprylic acid, carbonic acid, cinnamic acid, citric acid, cyclamic acid, dodecylsulfuric acid, ethane-1 ,2-disulfonic acid, ethanesulfonic acid, 2-hydroxyethanesulf
  • “Pharmaceutically acceptable base addition salt” refers to those salts which retain the biological effectiveness and properties of the free acids, which are not biologically or otherwise undesirable. These salts are prepared from addition of an inorganic base or an organic base to the free acid. Salts derived from inorganic bases include, but are not limited to, the sodium, potassium, lithium, ammonium, calcium, magnesium, iron, zinc, copper, manganese, aluminum salts and the like. Preferred inorganic salts are the ammonium, sodium, potassium, calcium, and magnesium salts.
  • Salts derived from organic bases include, but are not limited to, salts of primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines and basic ion exchange resins, such as ammonia, isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, diethanolamine, ethanolamine, deanol, 2-dimethylaminoethanol,
  • 2-diethylaminoethanol dicyclohexylamine, lysine, arginine, histidine, caffeine, procaine, hydrabamine, choline, betaine, benethamine, benzathine, ethylenediamine, glucosamine, methylglucamine, theobromine, triethanolamine, tromethamine, purines, piperazine, piperidine, /V-ethylpiperidine, polyamine resins and the like.
  • Particularly preferred organic bases are isopropylamine, diethylamine, ethanolamine,
  • a “pharmaceutical composition” refers to a formulation of a compound of the invention and a medium generally accepted in the art for the delivery of the biologically active compound to mammals, e.g., humans.
  • a medium includes all pharmaceutically acceptable carriers, diluents or excipients therefor.
  • “Therapeutically effective amount” refers to that amount of a compound of the invention which, when administered to a mammal, preferably a human, is sufficient to effect treatment of the disease or condition of interest in a mammal, preferably a human, having the disease or condition.
  • the amount of a compound of the invention which constitutes a “therapeutically effective amount” will vary depending on the compound, the disease or condition and its severity, the manner of
  • a “therapeutically effective amount” is that amount of a compound of invention which is sufficient to stimulate melanogenesis to address certain pigmentation disorders.
  • “Therapeutically effective amount” may differ from “cosmetically effective amount” in that the latter does not necessarily seek to address a pigmentation disorder. Rather, cosmetically effective amount of the claimed compound or composition refers to an amount that will effect a heightened level of melanogenesis (tanning) on normal skin. Thus, cosmetically effective amount is largely determined by aesthetics and personal preference.
  • Treating covers the treatment of the disease or condition of interest in a mammal, preferably a human, and includes:
  • the terms “disease” and “condition” may be used interchangeably or may be different in that the particular malady or condition may not have a known causative agent (so that etiology has not yet been worked out) and it is therefore not yet recognized as a disease but only as an undesirable condition or syndrome, wherein a more or less specific set of symptoms have been identified by clinicians.
  • the compounds of the invention, or their pharmaceutically acceptable salts may contain one or more asymmetric centers and may thus give rise to enantiomers, diastereomers, and other stereoisomeric forms that may be defined, in terms of absolute stereochemistry, as (R)- or (S)- or, as (D)- or (L)- for amino acids.
  • the present invention is meant to include all such possible isomers, as well as their racemic and optically pure forms.
  • Optically active (+) and (-), (/?)- and (S)-, or (D)- and (L)- isomers may be prepared using chiral synthons or chiral reagents, or resolved using conventional techniques, for example, chromatography and fractional crystallization.
  • stereoisomer refers to a compound made up of the same atoms bonded by the same bonds but having different three-dimensional structures, which are not interchangeable.
  • the present disclosure contemplates various stereoisomers and mixtures thereof and includes “enantiomers,” which refers to two stereoisomers whose molecules are nonsuperimposeable mirror images of one another.
  • the claimed compounds and compositions are capable of stimulating or activating one or more parameters related to melanogenesis. These parameters include, for example, melanin production, which is a direct result of melanogenesis. Other cellular events that may be indicative of melanogenesis include, for example, enhanced dendrite formation, elevations of the activities of the key enzymes involved in the melanogenesis pathway and/or the expression of the same.
  • the claimed compounds and compositions are effective in stimulating
  • melanogenesis at a rate comparable to UV radiation, but without the risks of cellular damage associated with UV exposure.
  • Disclosed herein include a method of stimulating melanogenesis in a mammal in need thereof, the method comprising administering to the mammal a pharmaceutically effective amount of a compound of Formula (I):
  • n 0, 1 , 2, or 3;
  • Ri is hydrogen, alkyl, haloalkyi, alkenyl, aralkyi or aryl;
  • R 2 is hydrogen, alkyl, haloalkyi, alkenyl, aralkyi or aryl;
  • R 3 is alkyl, alkenyl, aralkyi or aryl
  • R 4 is alkyl, alkenyl, aralkyi or aryl
  • each R 5 is the same or different and independently alkyl, halo, haloalkyi, aralkyi, heterocyclylalkyl, nitro, cyano, -C(0)R 6 , -C(0)OR 6 , -S(0) 2 -N(R 6 )R 7 , or -C(0)N(R 6 )R 7 ;
  • R 6 is hydrogen, alkyl, hydroxyalkyl, aralkyi or aryl
  • R 7 is hydrogen or alkyl
  • At least one R 5 of compounds of Formula (I) is an electron-withdrawing group, including, for example, halo, nitro,
  • R 5 of compounds of Formula (I) is -S(0) 2 -N(R 6 )R 7 .
  • R 5 is -S(0) 2 -NH(R 6 ), wherein R 6 is alkyl or hydroxyalkyl.
  • m is 1
  • R 5 is -S(0) 2 -NH(R 6 ), wherein R 6 is alkyl or hydroxyalkyl, and R 5 located at a position meta to the azo moiety of a compound of Formula (I).
  • Ri and R 2 are both hydrogens.
  • R 3 and R 4 are each independently alkyl or aralkyl.
  • R 3 and R 4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl.
  • the optionally substituted /V-heterocyclyl is optionally substituted piperazinyl, morpholinyl, pyrrolidinyl, or imidazolidinyl.
  • a further embodiment provides a method of stimulating melanogenesis in a mammal in need thereof by administering a pharmaceutically effective amount of a compound of Formula (la):
  • n 0, 1 , or 2;
  • Ri is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
  • R 2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
  • R 3 is alkyl, alkenyl, aralkyl or aryl
  • R 4 is alkyl, alkenyl, aralkyl or aryl
  • R 6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl
  • R 7 is hydrogen or alkyl
  • each R 8 is the same or different and independently alkyl, halo, haloalkyl, aralkyl, heterocyclylalkyl, nitro, cyano, -C(0)R 6 , -C(0)OR 6 , -S(0) 2 -N(R 6 )R 7 ,
  • Ri and R 2 are both hydrogens.
  • R 3 and R 4 are each independently alkyl or aralkyl.
  • R 3 and R 4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl.
  • the optionally substituted /V-heterocyclyl is optionally substituted piperazinyl, morpholinyl, pyrrolidinyl, or imidazolidinyl.
  • the method of stimulating melanogenesis in a mammal in need thereof comprises administering to the mammal a pharmaceutically effective amount of a compound of Formulae (I) or (la), wherein the compound is:
  • melanogenesis stimulation may be suitable for treating a number of pigmentation disorders, which results in increased pigmentation or restoration of pigmentation.
  • melanin is most prevalent in skin, it is also present in hair, the pigmented tissue underlying the iris of the eye, the stria vascularis of the inner ear, the brain tissues and neurons
  • stimulating melanogenesis in a mammal in need thereof, as set forth above in the Summary of the Invention, one embodiment of this method is wherein stimulating melanogenesis includes tanning.
  • the mammal has normal pigmentation and is in need of tanning in the absence of UV exposure.
  • the compounds of formula (I) or (la) could be applied to a person at risk of experiencing polymorphic light eruption, which is a skin irritation caused by sunlight.
  • polymorphic light eruption which is a skin irritation caused by sunlight.
  • 5-20% of fair skinned populations can be affected, but it can occur in any skin type. It is more common in females than in males.
  • Compounds of formula (I) or (la) may also be useful to treat other sunlight-related disorders such as solar urticaria, which is photodermatosis
  • the disorder may be caused by an antigen-antibody reaction.
  • one embodiment provides treating solar urticaria by topically administering a therapeutically effective amount of a compound of formula (I) or (la).
  • Compounds of formula (I) or (la) may also provide skin protection for porphyrias, which are the result of defects in enzymes needed at various steps of heme synthesis.
  • Clinical manifestations depend on the biochemical step in which the enzymatic defect occurs. If the enzymatic defects are in the initial steps of the metabolic cascade, early metabolic intermediates will accumulate, resulting in neurologic dysfunction. If the enzymatic defects are in the final steps, sunlight-induced cutaneous lesions (photosensitivity) due to porphyrin accumulation in the skin will develop.
  • one embodiment provides treating porphyria by topically administering a therapeutically effective amount of a compound of formula (I) or (la).
  • Leukoderma is characterized by light patches on the skin. Vitiligo, an immune mediated condition, is also associated with reduced pigment and nonfunctioning melanocytes in skin patches. Leukoderma is congenital while vitiligo is an acquired condition. Unlike albinism, the more common pigment disorders are not disorders of melanin quality, but rather of the pigment-producing cells (melanocytes) themselves, which may be reduced in number, absent, hyperactive, inactive or commonly with regional localization.
  • a further embodiment provides a method of restoring pigmentation in a mammal having a pigmentation disorder, wherein the method comprises administering to the mammal a therapeutically effective amount of a compound of Formulae (I) or (la).
  • one embodiment of this method is wherein the pigmentation disorder or condition is selected from the group consisting of vitiligo and leukoderma.
  • Another embodiment of this method is wherein the dermatological disorder is vitiligo.
  • Another embodiment of this method is wherein the dermatological disorder is leukoderma.
  • the light patches are results of pigmentation disorders such as leukoderma or vitiligo.
  • Compounds of formula (I) or (la) may be used to restore or change hair pigmentation (e.g., reversal of hair graying).
  • Hair color depends upon the distribution, type and amount of melanin in the middle layer of the hair shaft or cortex. Hair has only two types of pigments: dark (eumelanin) and light (phaeomelanin). They blend together to make up the wide range of hair colors. Without melanin, hair will grey and ultimately turn white.
  • Melanocytes exist at the openings on the skin's surface through which hair grows (follicles). Each hair grows from a single follicle. The process of scalp hair growth includes the anagen stage, when active growth occurs and can last from 2- 7 years.
  • the catagen stage is the phase during which hair growth begins to "shut down" and stop activity. It generally lasts 10- 20 days.
  • hair growth is completely at rest and the hair fiber falls out.
  • 10-15 % of our hair is in the telogen phase, which generally lasts 100 days for scalp hair.
  • the hair growth process starts again at the anagen phase.
  • melanocytes inject pigment (melanin) into cells containing keratin protein, which is the key component that makes up mammalian hair, skin, and nails.
  • melanocyctes continue to inject pigment into the hair's keratin, until aging reduces the production and/or injection of melanin.
  • genes regulate the exhaustion of the pigmentary potential of each individual hair follicle. This occurs at different rates in different hair follicles.
  • MSC melanocyte stem cells
  • one embodiment provides restoring hair color by topically administering a therapeutically effective amount of a compound of formula (I) or (la).
  • Compounds of formula (I) or (la) may be formulated into a formulation suitable for application to the human scalp, and applied on a daily or twice daily basis.
  • the follicular melanocytes are thus exposed to the melanogenesis-stimulating effect of the compounds.
  • the formulation may be in the form of a solution, aerosol, foam, cream, gel, and the like.
  • Neuromelanin is the dark pigment present in pigment-bearing neurons of certain deep brain nuclei. Both the substantia nigra and locus coeruleus can be easily identified grossly at the time of autopsy because of their dark pigmentation. In humans, these nuclei are not pigmented at the time of birth, but develop pigmentation during maturation to adulthood.
  • the pigment is made from oxyradical metabolites of monoamine neurotransmitters including dopamine and norepinephrine.
  • Parkinson's disease While the level of neuromelanin generally becomes higher throughout life in most people, the loss or lack of pigmented neurons from specific nuclei is seen in a variety of neurodegenerative diseases, including Parkinson's disease. In Parkinson's disease, there is a massive loss of dopamine-producing pigmented neurons in the substantia nigra (Zecca, Luigi; et al. "The absolute concentration of nigral
  • a further embodiment provides a method for treating a
  • the degenerative neurological disorder by locally or systemically administering a pharmaceutical composition comprising a compound of formula (I) or (la) in an amount effective in stimulating neuromelanin synthesis.
  • the degenerative neurological disorder is Parkinson's disease.
  • Hearing disorders may develop as a part of the aging process. However, hearing disorders are more prevalent and could occur prematurely in individuals with pigmentation disorders. It has been observed that melanin precursors are capable of preventing premature age-related and noise-induced hearing loss in albino mice. See, Murillo-Cuesta S. et al. Pigment Cell Melanoma Res. 23(1 ):72-83 (2010). Furthermore, a link has been observed between the absence of strial melanin with age-associated marginal cell loss and endocochlear potential decline. See, Ohlemiller K.K. et al., Hear Res. 249(1-2):1- 14 (2009).
  • the compounds of formula (I) or (la) may be applied intra-aurally or systemically for prevention or treatment of hearing disorders characterized by melanocyte insufficiency in the inner ear.
  • Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered topically.
  • Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered subcutaneously.
  • Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered systemically.
  • Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered orally.
  • Another embodiment of this method is wherein the pharmaceutical composition is a dermatological composition and the pharmaceutically acceptable excipient is a dermatologically acceptable excipient.
  • Another embodiment of this method is wherein the pharmaceutical composition is a systemic composition.
  • Another embodiment of this method is wherein the pharmaceutical composition is an oral composition.
  • Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered topically.
  • Compounds of formula (I) or (la) may also be delivered in a
  • subcutaneous depot or implant subcutaneous depot or implant.
  • Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered systemically (including injection).
  • Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered orally.
  • compounds of formula (I) or (la) are formulated into a table tablet containing one adult dose, to be sold as a prophylactic against sunburn.
  • the user would ingest one to three tablets per day, for example, and experience an increase in melanogenesis which would allow them to enjoy sunlight with less risk of skin damage.
  • Another embodiment of this method is wherein the pharmaceutical composition is a dermatological composition and the pharmaceutically acceptable excipient is a dermatologically acceptable excipient.
  • Another embodiment of this method is wherein the pharmaceutical composition is a systemic composition.
  • Another embodiment of this method is wherein the pharmaceutical composition is an oral composition.
  • n 0, 1 , or 2;
  • Ri is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl
  • R 2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl
  • R-i and R 2 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
  • R 3 is alkyl, alkenyl, aralkyl or aryl;
  • R 4 is alkyl, alkenyl, aralkyl or aryl
  • R 3 and R 4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
  • R 6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl;
  • R 7 is hydrogen or alkyl
  • each R 8 is the same or different and independently alkyl, halo, haloalkyl, aralkyl, heterocyclylalkyl, nitro, cyano, -C(0)R 6 , -C(0)OR 6 , -S(0) 2 -N(R 6 )R 7 , or -C(0)N(R 6 )R 7 .
  • Ri and R 2 are both hydrogens.
  • R 3 and R 4 are each independently alkyl or aralkyl.
  • R 3 and R 4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl.
  • the optionally substituted /V-heterocyclyl is optionally substituted piperazinyl, morpholinyl, pyrrolidinyl, or imidazolidinyl.
  • the compound of Formula (la) is:
  • a further embodiment provides a pharmaceutical composition
  • a pharmaceutical composition comprising a pharmaceutical effective amount of a compound of Formula (la), or a pharmaceutically acceptable salt thereof, and a pharmaceutical acceptable excipient.
  • the pharmaceutical composition is a dermatological composition comprising a dermatologically effective amount of a compound of Formula (la), or a dermatologically acceptable salt thereof, and a dermatologically acceptable excipient.
  • the dermatological composition is a gel formulation, an alcoholic gel formulation, a hydroalcoholic gel formulation, or a cream formulation.
  • the pharmaceutical composition is an oral composition comprising a dermatologically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt, and a pharmaceutically acceptable excipient.
  • Suitable protecting groups for hydroxy include trialkylsilyl or diarylalkylsilyl (e.g., f-butyldimethylsilyl, f-butyldiphenylsilyl or trimethylsilyl), tetrahydropyranyl, benzyl, and the like.
  • Suitable protecting groups for amino, amidino and guanidino include f-butoxycarbonyl, benzyloxycarbonyl, and the like.
  • Suitable protecting groups for mercapto include -C(0)-R 8 (where R 8 is alkyl, aryl or aralkyl), p-methoxybenzyl, trityl and the like.
  • Suitable protecting groups for carboxylic acid include alkyl, aryl or aralkyl esters.
  • the protecting group may also be a polymer resin such as a Wang resin or a 2-chlorotrityl chloride resin.
  • compounds of Formula (I) are prepared by first diazotizing a primary amine of formula (a) by treatment with hydrochloric acid and sodium nitrite.
  • the intermediate diazo compound of formula (b) is then treated, in the presence of a base, for example, sodium acetate, with malononitrile (c) to provide a compound of formula (d).
  • the compound of formula (d) is then reacted with a hydrazine (E) to provide diamino precursors (f) of the compounds of Formula (I).
  • Alkylation of one or more hydrogens of the amino groups according to known methods in the art provides compounds of Formula (I).
  • compositions comprising a compound of the invention, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient are one aspect of the present invention.
  • These pharmaceutical compositions may be in any form which allows for the active ingredient, i.e., a compound of formula (I) or (la), to be administered to a human in a therapeutically effective amount.
  • the pharmaceutical composition may be in the form of a semi-solid (gel), solid, liquid or gas (aerosol).
  • Typical routes of administration include, without limitation, systemic (including oral and parenteral), topical, buccal, transdermal, sublingual, nasal, rectal, vaginal, and intranasal administration.
  • parenteral as used herein includes subcutaneous injections, needle-less injections, intravenous, intramuscular, epidural, intrasternal injection or infusion techniques.
  • Pharmaceutical compositions of the invention are formulated so as to allow the active ingredients contained therein to be bioavailable upon administration of the composition to a human.
  • Pharmaceutical compositions of the invention that will be administered to a human may take the form of one or more dosage units, where for example, a tablet, capsule, cachet or patch may be a single dosage unit, and a container of a pharmaceutical composition of the invention in aerosol form may hold a plurality of dosage units.
  • the compound of formula (I) or (la) is preferably administered to the skin (i.e., topically) of the human in need thereof in dermatologically acceptable compositions, as described in more detail below.
  • dermatologically acceptable compositions e.g., when a dermatological composition comprising a compound of formula (I) or (la) and a dermatologically acceptable excipient is placed upon the skin of the human in need thereof
  • the compound of formula (I) or (la) is in continuous contact with the skin of the patient, thereby effecting treatment.
  • any suitable amount of a compound of formula (I) or (la) can be employed in such dermatological compositions, provided the amount employed effectively stimulate melanogenesis and remains stable in the composition over a prolonged period of time.
  • the stability is over a prolonged period of time, e.g., up to about 3 years, up to 1 year, or up to about 6 months, which is typical in the manufacturing, packaging, shipping and/or storage of dermatologically acceptable compositions.
  • a compound of formula (I) or (la) can be in solution, partially in solution with an undissolved portion or completely undissolved suspension.
  • a compound of formula (I) or (la) can be present in a dermatological composition of the invention in a concentration range from about 0.001 wt.% to about 80 wt.%, from about 0.001 wt.% to about 50 wt.%, from about 0.001 wt.% to about 25 wt.%, or from about 0.001 wt.% to about 6 wt.% of the dermatological composition.
  • a compound of formula (I) or (la) can be present in a concentration range of from about 0.001 wt.% to about 10 wt.%, from about 0.1 wt.% to about 10 wt.% or from about 1 .0 wt.% to about 5.0 wt.% of the dermatological composition.
  • an effective dose may range from 0.01 %-5% of a compound of formula (I) or (la), given 1 - 4 times daily for 2-3 months.
  • a dermatological formulation of a compound of formula (I) or (la) to be administered topically contains (by weight) about 3% of a compound of Formulae (I) or (la) in about 40%
  • a dermatological composition of the invention can be in the form of a solution, lotion, foam, gel, cream and/or ointment.
  • the dermatological composition will be a topical formulation, for example, a gel, foam, cream or ointment.
  • a dermatological composition of the invention can contain one or more "lipophilic solvent(s)" that acts as a carrier into the pilosebaceous unit.
  • a lipophilic solvent useful in the invention can be miscible with water and/or lower chain alcohols and have a vapor pressure less than water at 25°C ( ⁇ 23.8 mm Hg).
  • a lipophilic solvent useful in the invention can be a glycol, specifically propylene glycol.
  • the propylene glycol can be from the class of polyethylene glycols, specifically polyethylene glycols ranging in molecular weight from 200 to 20000.
  • the solvent would be part of a class of glycol ethers. More specifically, a lipophilic solvent of the invention would be diethylene glycol monoethyl ether (“DGME”) or 2-(2-ethoxyethoxy)ethanol (TranscutolTM).
  • DGME diethylene glycol monoethyl ether
  • TranscutolTM 2-(2-ethoxyethoxy)ethanol
  • a dermatological composition of the invention can also contain one or more "filler(s)" that has a vapor pressure greater than or equal to 23.8 mm Hg at 25°C.
  • the filler should have a vapor pressure greater than or equal to the lipophilic solvent as to concentrate the compound of formula (I) or (la) on the skin.
  • Preferred concentration range of a single filler or the total of a combination of fillers can be from about 0.1 wt.% to about 10 wt. %, more preferably from about 10 wt. % to about 50 wt.%, more specifically from about 50 wt.% to about 95 wt.% of the dermatological composition.
  • Non-limiting examples for use herein include water and lower alcohols, including ethanol, 2-propanol and n-propanol. More preferably, the filler is water, ethanol and/or 2-propanol. Specifically, the filler would be ethanol and/or water.
  • a dermatological composition of the invention can also contain one or more "humectant(s)" used to provide a moistening effect.
  • the humectant remains stable in the composition. Any suitable concentration of a single humectant or a combination of humectants can be employed, provided that the resulting
  • humectant concentration provides the desired moistening effect.
  • suitable amount of humectant will depend upon the specific humectant or humectants employed.
  • Preferred concentration range of a single humectant or the total of a combination of humectants can be from about 0.1 wt.% to about 70 wt.%, more preferably from about 5.0 wt.% to about 30 wt.%, more specifically from about 10 wt.% to about 25 wt.% of the dermatological composition.
  • Non-limiting examples for use herein include glycerin, polyhydric alcohols and silicone oils. More preferably, the humectant is glycerin, propylene glycol and/or cyclomethicone. Specifically, the filler would be glycerine and/or cyclomethicone.
  • a dermatological composition of the invention can also contain a gelling agent that increases the viscosity of the final solution.
  • the gelling agent can also act as an emulsifying agent.
  • the present dermatological compositions can form clear gels and soft gels, which upon application to the skin can break down and deteriorate, affording gels that do not dry on the skin.
  • concentration and combination of gelling agents will depend on the physical stability of the finished product.
  • Preferred concentration range of a gelling agent can be from about 0.01 wt.% to about 20 wt.%, more preferably from about 0.1 wt.% to about 10 wt.%, more specifically from about 0.5 wt. % to about 5 wt.% of the dermatological composition.
  • Non-limiting examples for use herein include classes of celluloses, acrylate polymers and acrylate
  • hydroxypropyl cellulose, hydroxymethyl cellulose, Pluronic PF127 polymer, carbomer 980, carbomer 1342 and carbomer 940 more preferably hydroxypropyl cellulose, Pluronic PF127 carbomer 980 and carbomer 1342, more specifically hydroxypropyl cellulose (Klucel® EF, GF and/or HF), Pluronic PF127, carbomer 980 and/or carbomer 1342 (Pemulen® TR-1 , TR-2 and/or Carbopol® ETD 2020).
  • a dermatological composition of the invention can contain one or more anti-oxidants, radical scavengers, and/or stabilizing agents, preferred concentration range from about 0.001 wt.% to about 0.1 wt.%, more preferably from about 0.1 wt.% to about 5 wt.% of the dermatological composition.
  • Non-limiting examples for use herein include butylatedhydroxytoluene, butylatedhydroxyanisole, ascorbyl palmitate, citric acid, vitamin E, vitamin E acetate, vitamin E-TPGS, ascorbic acid, tocophersolan and propyl gallate. More specifically the anti-oxidant can be ascorbyl palmitate, vitamin E acetate, vitamin E-TPGS, vitamin E or butylatedhydroxytoluene.
  • a dermatological composition of the invention can also contain preservatives that exhibit anti-bacterial and/or anti-fungal properties. Preservatives can be present in a gelled dermatological composition of the invention to minimize bacterial and/or fungal over its shelf-life. Preferred concentration range of
  • preservatives in a dermatological composition of the invention can be from about 0.001 wt.% to about 0.01 wt.%, more preferably from about 0.01 wt.% to about 0.5 wt.% of the dermatological composition.
  • Non-limiting examples for use herein include diazolidinyl urea, methylparaben, propylparaben, tetrasodium EDTA, and
  • ethylparaben More specifically the preservative would be a combination of
  • a dermatological composition can optionally include one or more chelating agents.
  • chelating agent or “chelator” refers to those skin benefit agents capable of removing a metal ion from a system by forming a complex so that the metal ion cannot readily participate in or catalyze chemical reactions.
  • the chelating agents for use herein are preferably formulated at
  • Non-limiting examples for use herein include EDTA, disodium edeate, dipotassium edeate, cyclodextrin, trisodium edetate, tetrasodium edetate, citric acid, sodium citrate, gluconic acid and potassium gluconate.
  • the chelating agent can be EDTA, disodium edeate, dipotassium edate, trisodium edetate or potassium gluconate.
  • compositions of this invention can be provided in any cosmetically suitable form, preferably as a lotion or a cream, but also in an ointment or oil base, as well as a sprayable liquid form (e.g., a spray that includes the claimed compound in a base, vehicle or carrier that dries in a cosmetically acceptable way without the greasy appearance that a lotion or ointment would have when applied to the skin), or pre-loaded towelettes or wipes.
  • a sprayable liquid form e.g., a spray that includes the claimed compound in a base, vehicle or carrier that dries in a cosmetically acceptable way without the greasy appearance that a lotion or ointment would have when applied to the skin
  • pre-loaded towelettes or wipes e.g., a spray that includes the claimed compound in a base, vehicle or carrier that dries in a cosmetically acceptable way without the greasy appearance that a lotion or ointment would have when applied to the skin
  • compositions of the invention can include one or more compatible cosmetically acceptable adjuvants commonly used, such as colorants, fragrances, emollients, humectants and the like, as well as botanicals, such as aloe, chamomile and the like.
  • the skin of the human to be treated can be optionally pre-treated (such as washing the skin with soap and water or cleansing the skin with an alcohol-based cleanser) prior to administration of the dermatological composition of the invention.
  • a compound of formula (I) or (la) or a pharmaceutical composition comprising a compound of formula (I) or (la) may also be administered systemically or orally, to the human in need thereof in pharmaceutically acceptable compositions, as described in more detail below.
  • a pharmaceutical composition of the invention to be orally administered can be prepared by combining a compound of formula (I) or (la) with an appropriate pharmaceutically acceptable carrier, diluent or excipient by standard methods known to one skilled in the art.
  • Pharmaceutical compositions of the invention are formulated so as to allow the compound of formula (I) or (la) contained therein to be bioavailable upon administration of the composition to a human.
  • a pharmaceutical composition of the invention to be orally administered may be formulated into a powder, granule, compressed tablet, pill, capsule, chewing gum, wafer or the like form.
  • Such a solid composition will typically contain one or more inert diluents or edible carriers.
  • binders such as carboxymethylcellulose, ethyl cellulose, microcrystalline cellulose, gum tragacanth or gelatin; excipients such as starch, lactose or dextrins, disintegrating agents such as alginic acid, sodium alginate, Primogel, corn starch and the like; lubricants such as magnesium stearate or Sterotex; glidants such as colloidal silicon dioxide; sweetening agents such as sucrose or saccharin; a flavoring agent such as peppermint, methyl salicylate or orange flavoring; and a coloring agent.
  • excipients such as starch, lactose or dextrins, disintegrating agents such as alginic acid, sodium alginate, Primogel, corn starch and the like
  • lubricants such as magnesium stearate or Sterotex
  • glidants such as colloidal silicon dioxide
  • sweetening agents such as sucrose or saccharin
  • a flavoring agent such as peppermint, methyl sal
  • a pharmaceutical composition of the invention is in the form of a capsule, for example, a gelatin capsule, it may contain, in addition to materials of the above type, a liquid carrier such as polyethylene glycol or oil.
  • a pharmaceutical composition of the invention to be orally administered may also be in the form of a liquid, for example, an elixir, syrup, solution, emulsion or suspension.
  • the pharmaceutical composition may also optionally contain one or more of a sweetening agent, preservatives, dye/colorant and flavor enhancer. .
  • Liquid pharmaceutical compositions of the invention may also include one or more of the following adjuvants: sterile water, saline solution (preferably physiological saline solution), Ringer's solution, isotonic sodium chloride, fixed oils such as synthetic mono or diglycerides which may serve as the solvent or suspending medium, polyethylene glycols, glycerin, propylene glycol or other solvents; antibacterial agents such as benzyl alcohol or methyl paraben; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates or phosphates and agents for the adjustment of tonicity such as sodium chloride or dextrose.
  • adjuvants sterile water, saline solution (preferably physiological saline solution), Ringer's solution, isotonic sodium chloride, fixed oils such as synthetic mono or diglycerides which may serve as the solvent or suspending medium, polyethylene glycols,
  • a liquid pharmaceutical composition of the invention contains a therapeutically effective amount of a compound of formula (I) or (la) when administered to a human in need thereof. Typically, this amount is at least 0.01 % of a compound of formula (I) or (la) in the composition. This amount may be varied to be between about 0.1 wt.% and about 70% of the total weight of the composition.
  • Preferred oral pharmaceutical compositions contain a compound of formula (I) or (la) at a
  • a pharmaceutical composition of the invention may include various materials, which modify the physical form of a solid or liquid dosage unit.
  • the composition may include materials that form a coating shell around the active ingredient.
  • the materials that form the coating shell are typically inert, and may be selected from, for example, sugar, shellac, and other enteric coating agents.
  • the active ingredient may be encased in a gelatin capsule.
  • a pharmaceutical composition of the invention in solid or liquid form may also include an agent that binds to a compound of formula (I) or (la) and thereby assists in the systemic delivery of the compound of formula (I) or (la).
  • Suitable agents that may act in this capacity include a monoclonal or polyclonal antibody, a protein or a liposome.
  • Systemic administration of the pharmaceutical compositions of the invention also include administration by injection, e.g., subcutaneous, intravenous, intramuscular, intrathecal or intraperitoneal injection, as well as transdermal, transmucosal, or pulmonary administration and needle-less injection administration.
  • injection e.g., subcutaneous, intravenous, intramuscular, intrathecal or intraperitoneal injection, as well as transdermal, transmucosal, or pulmonary administration and needle-less injection administration.
  • Useful injectable pharmaceutical compositions include sterile suspensions, solutions or emulsions of the active compound(s) in aqueous or oily vehicles.
  • the compositions may also contain formulating agents, such as suspending, stabilizing and/or dispersing agent.
  • the pharmaceutical compositions for injection may be presented in unit dosage form, e.g., in ampules or in multidose containers, and may contain added preservatives.
  • the injectable pharmaceutical compositions may be provided in powder form for reconstitution with a suitable vehicle, including but not limited to sterile pyrogen free water, buffer, dextrose solution, etc., before use.
  • a suitable vehicle including but not limited to sterile pyrogen free water, buffer, dextrose solution, etc.
  • the active compound i.e., a compound of formula (I) or (la)
  • the active compound may be dried by any art-known technique, such as lyophilization, and reconstituted prior to use.
  • Liposomes and emulsions are well-known examples of delivery vehicles that may be used to deliver active compound(s) or prodrug(s).
  • Certain organic solvents such as dimethylsulfoxide (DMSO) may also be employed, although usually at the cost of greater toxicity.
  • DMSO dimethylsulfoxide
  • compositions of the invention may, if desired, be presented in a pack or dispenser device which may contain one or more unit dosage forms containing the active compound(s).
  • the pack may, for example, comprise metal or plastic foil, such as a blister pack.
  • the pack or dispenser device may be
  • compositions of the invention as set forth above may be prepared by methodology well known in the pharmaceutical art or by the method described herein. See, for example, Remington's Pharmaceutical Sciences, 18th Ed., (Mack Publishing Company, Easton, Pennsylvania, 1990).
  • compositions of the invention are administered to a human in a therapeutically effective amount, which will vary depending upon a variety of factors including the activity of the compound of formula (I) or (la); the metabolic stability and length of action of the compound of formula (I) or (la); the age, body weight, general health, sex, and diet of the human; the mode and time of
  • a therapeutically effective daily dose of a compound of formula (I) or (la) is (for a 70 kg mammal) from about 0.001 mg/kg (i.e., 0.07 mg) to about 100 mg/kg (i.e., 7.0 gm); preferably a therapeutically effective dose is (for a 70 kg mammal) from about 0.01 mg/kg (i.e., 0.7 mg) to about 50 mg/kg (i.e., 3.5 gm); more preferably a therapeutically effective dose is (for a 70 kg mammal) from about 1 mg/kg (i.e., 70 mg) to about 25 mg/kg (i.e., 1.75 gm).
  • melanogenesis these parameters include, for example, melanin production, which is a direct result of melanogenesis.
  • Other cellular events that may be indicative of melanogenesis include, for example, enhanced dendrite formation, elevations of the activities of the key enzymes involved in the melanogenesis pathway and/or the expression of the same.
  • dendrite formation i.e., dendritogenesis
  • melanocytes are required for transport of melanosomes to the periphery of melanocytes for subsequent transfer to keratinocytes.
  • Dendrites are branched projections formed from
  • melanocytes The dendricity of melanocytes is typically measured by the number and length of the dendrites.
  • Primary dendrites refer to dendrites that extruded directly from the cell body, whereas secondary dendrites originate from primary dendrites and so forth.
  • one dendritic melanocyte may interact with about 36 keratinocytes to supply these cells with melanin.
  • UV light is a prominent stimulus of melanocyte dendricity.
  • the initial process of dendrite formation in human melanocytes in response to UV light radiation and keratinocyte-conditioned media has been shown to involve increased formation of microfilaments and actin polymerization.
  • melanocytes form long branching dendrites.
  • Melanocyte dendricity can also be induced by UV light in the absence of keratinocytes, although the underlying mechanism is unknown.
  • UV light radiation can also act indirectly on melanocytes by stimulating the release of keratinocyte-derived factors that in turn regulate melanogenesis.
  • a-melanocyte-stimulating hormone a potent endogenous activator of melanogenesis.
  • Other hormones such as endothelin-1 and nerve growth factor, are also capable of inducing melanocyte dendrite formation.
  • Dendrite extension in mouse B16-F1 melanoma cells in response to keratinocyte- conditioned medium and in melanocytes in response to a-MSH has been shown to require actin assembly. Scott et al. supra.
  • the claimed compounds and compositions are capable of stimulating dendrite formation in human melanocytes as well as human and mouse melanoma cells within 24 hours of treatment, in the absence of UV radiation.
  • the claimed compounds and compositions are effective in stimulating
  • melanogenesis at a rate comparable to UV radiation, but without the risks of cellular damage associated with UV exposure.
  • tyrosinase a rate- limiting enzyme in pigmentation pathway for converting tyrosine to melanin
  • tyrosinase a rate- limiting enzyme in pigmentation pathway for converting tyrosine to melanin
  • HEMn-LP neonatal light-pigmented
  • HEMn-DP dark-pigmented
  • HEMa-LP light-pigmented adult
  • melanoma cells are dendritic and contain moderate amounts of melanin, which make them suitable for dendritogenesis and pigmentation studies (Huberman 1979, Busca 1996, Englaro 1998, Oka 2000).
  • Metastatic mouse B16-F10 melanoma (ATCC number CRL-6475) and human G361 melanoma cells (ATCC number CRL-1424) were acquired from the American Type Culture Collection (ATCC).
  • Primary human Mel-Ho melanoma cells DSMZ number: ACC 62
  • DSMZ Deutsche Sommlung con Mikroorganismen end Aelkulturen GmbH
  • the claimed compounds A-D, as well as compounds E and F were tested in vitro for their potential effects on cell morphology and pigmentation-related changes.
  • Forskolin and FK506 purchased from Sigma-Aldrich, which are known to affect pigmentation, were also tested for purposes of comparison.
  • Cells were seeded in growth medium at a density of 2x10 5 to 5x10 5 cells per well (75%-80% confluency) in 6-well plates and allowed to settle overnight.
  • e test compounds were dissolved in dimethylsulfoxide (DMSO) and subsequently diluted with culture medium.
  • Final DMSO concentrations in cell cultures were 0.1 % or less, levels that did not affect cell viability, tyrosinase activity or melanin levels.
  • Petri dishes with a diameter of 65 mm were used in the majority of studies while 96-well microtiter plates were used in cell viability experiments and 75 cm 2 tissue culture flasks were implemented to maximize the melanin signal with HEMn-LP. Cell cultures at the end of experiments typically had achieved 70%-80% confluency.
  • Untreated cells or cells treated with drug-solvent served as controls. At the indicated sampling times, pictures of the cells were taken and whole-cell extracts were prepared for assessment of the melanogenesis-related parameters.
  • Tyrosinase activity was determined using a dihydroxyphenylalanine
  • the reaction mixture consisted of 150 ⁇ of cell lysate and 10 ⁇ of 10 mM L-DOPA in PBS. Following 60 min at 37°C, the absorbance of the mixture was measured at an absorbance of 490 nm, corrected for lysate protein concentration and expressed as a percentage of the control result (100%).
  • the cells were seeded at a density of 9x10 4 cells per well in six-well plates and treated with the tested compounds for 24, 48, or 72 h.
  • Cells maintained in medium alone and cells treated with 0.1 % DMSO served as assay controls.
  • the cellular dendricity was determined by counting the total number of primary, secondary and tertiary dendrites.
  • Primary dendrites were considered dendrites that extruded directly from the cell body. In order to be included in the count, dendrite length needed to be at least one-third of the cell body diameter. For dendrites to be deemed secondary, these had to originate from a primary dendrite with a length that was at least one-third that of the primary dendrite.
  • tertiary dendrites originated from a secondary dendrite with a length that was at least one-third that of the second dendrite. For instance, five non-overlapping images of each treatment well were taken and 20 cells per image field were subjected to dendrite analysis. Protein Expression
  • Antibodies against the following proteins were used: actin (polyclonal; 1 :20,000 dilution; Sigma), tyrosinase (polyclonal; 1 :500 dilution; Santa Cruz), MITF (monoclonal [C5]; 1 :1000 dilution; Abeam), TRP1 (polyclonal; 1 :500 dilution; Santa Cruz), and TRP2 (polyclonal; 1 :500 dilution; Santa Cruz). All antibodies were diluted in TBS-T containing 5% BSA.
  • the membrane was incubated with anti-goat (1 :10,000 dilution; Santa Cruz) or anti-mouse IgG horseradish peroxidase-linked antibody (1 :10,000 dilution; Cell Signaling) in TBS-T for 1 h at room temperature and subjected to the enhanced chemiluminescence (ECL) detection system (GE).
  • ECL enhanced chemiluminescence
  • HEMn-DP were incubated in 96-well microtiter plates with test agents for 72 h.
  • the cell viability assay is based on the conversion of the 3-(4,5-dimethylthiazol-2-yl)-5-(3- carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H- tetrazolium, inner salt (MTS, Promega Corporation, Madison, Wl), by the cellular mitochondrial enzyme succinate- dehydrogenase into a soluble blue-colored formazan product that is measured spectrophotometrically.
  • MTS was added into cell cultures and incubated at 37°C under 5% C0 2 until sufficient color development was achieved (optical density value of 0.6- 1.0 units).
  • the absorbance of the formazan product was read using a microplate reader set at a wavelength of 490 nm.
  • Figure 1 demonstrates that Compound A reproducibly increased melanin levels in HEMn-LP and HEMn-DP as determined by cell pellet appearance (A) or melanin determinations (B), respectively. Similar darkening was observed for cell pellets generated with HEMn-DP following Compound A treatment (data not shown). On average, Compound A increased HEMn-DP melanin levels by 25%-75% in a dose- dependent manner as determined with melanin extraction and spectrophotometry methodologies. As a comparison, Forskolin had no effect on melanin levels while FK506 increased HEMn-DP melanin expression at some test concentrations. It was difficult to determine, however, the melanin levels for HEMn-LP due to the insensitivity of the assay to reliably detect this substance in extracts prepared from these cells using 65-mm sized petri dishes.
  • Compound A demonstrated similar effects on melanin levels in the melanoma cell lines. As shown in Figure 2, Compound A increased melanin levels 2.8 fold in B16-F10 and 2.7 fold in G361 cells after 48 h, when compared to a control of DMSO treatment. FK506 was also shown to have promoted melanin production in B16-F10 and Mel-Ho cells. Compound A treated Mel-Ho cells did not contain enough melanin to be assayed after 24 h and produced only 1.4 fold more melanin content than the control cells after 48 h. Figure 2(C). It is possible that the Mel-Ho cells have a lower capacity for melanin production or that with drug treatment it might take longer for these cells to achieve similar melanin levels in B16-F10 and G361 cells.
  • tyrosinase in the melanin synthesis pathway was investigated.
  • Responses of primary human melanocytes from three different sources (HEMn-LP, HEMn-DP, HEMa-LP) were evaluated.
  • HEMn-LP human melanocytes from three different sources
  • HEMn-DP human melanocytes from three different sources
  • HEMa-LP human melanocytes from three different sources
  • an increase in tyrosinase activity about 200% was evident for cells of all origin treated with Compound A at 5 ⁇ for 72 hours.
  • the enzymatic activity was also demonstrated to be concentration dependent.
  • At a concentration of 1 ⁇ little change in tyrosinase activity was observed with Compound A.
  • the enzyme activity markedly increased when Compound A was tested at 10 ⁇ on HEM-LP and HEM-DP. Highly consistent responses were obtained in different experiments and for cells from different donors.
  • Dendrite counting was performed on the B16-F10 cells. As shown in Figure 7, while FK506 had lower effects on primary dendrite formation, Compound A greatly increased dendricity in these cells. For example, after 24 h of Compound A treatment, 42% of the cell population exhibited more than 4 dendrites compared to 2 dendrites for the majority of DMSO treated cells. The large standard deviation between the experiments may be because the drugs used in the second experiment had undergone several cycles of freeze and thaw. It was observed in the second experiment that it took longer for the drugs to induce morphological changes in B16- F10 cells. It should also be noted that different counting methods were used in the two experiments. In the first experiment, five non-overlapping images were taken of each treatment well and dendrites of 20 cells per image field were counted. In the second experiment, dendrites of 10 cells from 5 non-overlapping fields were counted directly from the microscope due to camera breakdown.
  • Compound A also induced dendrite formation in the human melanocytes.
  • a highly dendritic morphology of Compound A-treated HEMn-DP is evident. See Figure 8(A).
  • Compound A increased mean dendrite numbers, the proportion of cells with more than three dendrites as well as the number of cells with secondary and tertiary (branching) dendrites.
  • the colorimetric MTS assay was used to assess the impact of
  • Table 3 summarizes the effects of Compound A and related compounds on melanogenesis-related parameters in B16-F10 cells as compared to a DMSO control.
  • a patient with solar urticaria receives a single dose (e.g., 0.07 mg to 7 mg for a 70 kg individual) by subcutaneous, subcutaneous implant, or oral administration of Compound A during winter months (November, December, January, February) in the British Columbia, when sun exposure is minimal .
  • Melanin density was assessed spectrophotometrically over a two-month time course, in situ, if the dermis was the therapeutic target.

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Abstract

Disclosed herein are pyrazole compounds of formula (Ia) and methods of stimulating melanogenesis or restoring pigmentation by administering to a mammal in need thereof: (The chemical formula should be inserted here.)

Description

COMPOUNDS AND COMPOSITIONS FOR MODULATING MELANOGENESIS AND PIGMENTATION ACTIVITIES
BACKGROUND Technical Field
This disclosure is generally related to compounds and pharmaceutical compositions that modulate melanogenesis and use of such compounds for treating or preventing skin pigmentation disorders as well as addressing cosmetic needs for tanning.
Background
Melanin is the major body pigment and the primary determinate of human skin color. In most tissues, melanocytes produce melanin within melanosomes by converting tyrosine to various forms of melanin. The melanin-containing
melanosomes are transported to the periphery of the melanocytes, which have a dendritic morphology, before being transferred to epidermal keratinocytes.
Production of melanin (melanogenesis) can be stimulated by, for example, ultraviolet (UV) light. UV-induced melanogenesis is skin's major defense against further UV damage. More specifically, melanin pigmentation protects against UV damage by absorbing UV photons and UV-generated free radicals before they can react with DNA and other critical cellular components. However, cumulative exposure to UV light can result in an increased risk of skin cancer and skin damage (e.g., premature aging and wrinkles). Thus, pharmaceutical agents that induce
melanogenesis are of medical interest for protecting skin from photodamage without UV exposure or the risk of skin cancer. The benefit can be extended to addressing certain cosmetic needs for tanning, especially sunless tanning.
Pharmaceutical agents that modulate melanogenesis can also address certain skin pigmentation disorders. Skin pigmentation disorders include, for example, hyper-pigmentation and hypo-pigmentation. Hyper-pigmentation (excessive pigmentation) can be associated with inflammatory responses, such as in keloid scars, or with local abnormal melanocyte function, as in dysplastic nevi or malignant melanoma. The counterpart to this condition is known as hypo-pigmentation, when there is a reduction or absence of pigmentation. In its most extreme form, hypo- pigmentation is represented by albinism, an inherited condition where there is a complete absence of skin pigment due to absence or defect in an enzyme involved in the production of melanin. Another form of hypo-pigmentation is leukoderma characterized by light patches on the skin. Thus, pharmaceutical agents that stimulate the production of melanin could be effective therapy for skin pigmentation disorders that are associated with defective or absent melanocytes.
A variety of agents are known to affect melanogenesis in primary melanocytes and/or melanoma cells in vitro. These include prostaglandins (PG), endothelin-1 , psoralens with UVA light (PUVA), dimethylsulfoxide (DMSO), L-tyrosine, L-Dopa, lysosomotropic agents, diacylglycerols, thymidine dinucleotides, DNA fragments, a-melanocyte-stimulating hormone (MSH) analogs, 3-isobutyl-1- methylxanthine (IBMX), forskolin, FK506 (Tacrolimus), nitric oxide donors, and bicyclic monoterpene (BMT) diols. Kang et al. Br. J. Dermatol. 155:1037-1040 (2006); and Solano et al. Pigment Cell Res. 19:550-571 (2006). Some of these agents have also been shown to increase pigmentation when applied topically onto mouse and/or human skin. For example, repeat topical application of forskolin onto mouse ears stimulated skin pigmentation. D'Orazio et al. Nature 443:340-344 (2006).
Thus, there is a continuing need for an effective therapy for treating or preventing photodamage and skin pigmentation disorders as well as addressing cosmetic needs for sunless tanning.
BRIEF SUMMARY
In one embodiment, described herein is a compound of Formula (la):
Figure imgf000005_0001
wherein,
n is 0, 1 , or 2;
Ri is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
R2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
or R-i and R2 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
R3 is alkyl, alkenyl, aralkyl or aryl;
R4 is alkyl, alkenyl, aralkyl or aryl;
or R3 and R4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
R6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl;
R7 is hydrogen or alkyl; or
R6 and R7 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl, and
each R8 is the same or different and independently alkyl, halo, haloalkyl, aralkyl, heterocyclylalkyl, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7,
or -C(0)N(R6)R7.
provided that, the compound of Formula (la) is not:
4-[/V-(3-amino-5-pyrrolidin-1-yl-pyrazol-4-ylidene)-hydrazino]- benzenesulfonamide;
4-{/V'-[3-amino-5-(4-methylpiperazin-1-yl)-pyrazol-4-ylidene]-hydrazino}- benzenesulfonamide;
3-[/V-(3-amino-5-pyrrolidin-1-yl-pyrazol-4-ylidene)-hydrazino]-/V-methyl- benzenesulfonamide; 3-[/V-(3-amino-5-pyrrolidin-1-yl-pyrazol-4-ylidene)-hydrazino]- benzenesulfonamide;
3-[/V-(3-amino-5-dimethylamino-pyrazol-4-ylidene)-hydrazino]- benzenesulfonamide;
3-[/V-(3-amino-5-dimethylamino-pyrazol-4-ylidene)-hydrazino]-/V-methyl- benzenesulfonamide;
3-[/V-(3-amino-5-morpholin-4-yl-pyrazol-4-ylidene)-hydrazino]- benzenesulfonamide;
3-[/V-(3-amino-5-morpholin-4-yl-pyrazol-4-ylidene)-hydrazino]-/V-methyl- benzenesulfonamide; or
3-[/V-(3-amino-5-morpholin-4-yl-pyrazol-4-ylidene)-hydrazino]-/\/-(2- hydroxyethyl)-benzenesulfonamide.
A further embodiment describes a pharmaceutical composition comprising a pharmaceutical effective amount of a compound of Formula (la), or a pharmaceutically acceptable salt thereof, and a pharmaceutical acceptable excipient.
In a preferred embodiment, the pharmaceutical composition is a dermatological composition.
A further embodiment provides a method of stimulating melanogenesis in a mammal in need thereof, the method comprising: administering to the mammal a of Formula (I):
Figure imgf000006_0001
(I)
wherein,
m is 0, 1 , 2, or 3;
Ri is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
R2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
or R-i and R2 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl; R3 is alkyl, alkenyl, aralkyl or aryl;
R4 is alkyl, alkenyl, aralkyl or aryl;
or R3 and R4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
each R5 is the same or different and independently alkyl, halo, haloalkyl, aralkyl, heterocyclylalkyl, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7,
or -C(0)N(R6)R7;
R6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl;
R7 is hydrogen or alkyl; or
R6 and R7 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl.
In a preferred embodiment, the method of stimulating melanogenesis in a mammal in need thereof administering to the mammal a pharmaceutically effective amount of a compound of Formula (la):
Figure imgf000007_0001
(la)
wherein,
n is 0, 1 , or 2;
Ri is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
R2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
or Ri and R2 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
R3 is alkyl, alkenyl, aralkyl or aryl;
R4 is alkyl, alkenyl, aralkyl or aryl;
or R3 and R4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
R6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl; R7 is hydrogen or alkyl; or
R6 and R7 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl, and
each R8 is the same or different and independently alkyl, halo, haloalkyl, aralkyl, heterocyclylalkyl, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7,
or -C(0)N(R6)R7.
In various embodiments, the mammal has a pigmentation disorder.
In various embodiments, the mammal's pigmentation disorder is vitiligo or leukoderma.
In certain embodiment, the mammal's pigmentation disorder is characterized by inadequate or absent melanocytes.
In various embodiments stimulating melanogenesis includes tanning. In a preferred embodiment, the mammal has normal pigmentation and is in need of tanning in the absence of UV exposure.
A further embodiment provides a method of restoring pigmentation in a mammal having a pigmentation disorder, wherein the method comprises administering to the mammal of a compound of Formulae (I):
Figure imgf000008_0001
(I)
wherein,
m is 0, 1 , 2, or 3;
Ri is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
R2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
or Ri and R2 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
R3 is alkyl, alkenyl, aralkyl or aryl;
R4 is alkyl, alkenyl, aralkyl or aryl; or R3 and R4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
each R5 is the same or different and independently alkyl, halo, haloalkyl, aralkyl, heterocyclylalkyl, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7,
or -C(0)N(R6)R7;
R6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl;
R7 is hydrogen or alkyl; or
R6 and R7 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl.
In a preferred embodiment, the compound is of Formula (la):
Yet a further embodiment provides a method for treating porphyria comprising: topically administering a therapeutically effective amount of a compound of formula (I) or (la) to a subject in need thereof.
Yet a further embodiment provides a method for treating solar urticaria comprising: topically administering a therapeutically effective amount of a compound of formula (I) or (la) to a subject in need thereof.
Yet a further embodiment provides a method for treating light patches on mammalian skin comprising: topically administering a therapeutically effective amount of a compound of formula (I) or (la). In various embodiments, the light patches are results of pigmentation disorders such as leukoderma or vitiligo.
Another embodiment provides a method for restoring hair color by topically administering a therapeutically effective amount of a compound of formula (I) or (la) to the scalp of a subject in need thereof.
Yet a further embodiment provides a method for treating a degenerative neurological disorder by locally or systemically administering a pharmaceutical composition comprising a compound of formula (I) or (la) in an amount effective in stimulating neuromelanin synthesis. In certain embodiment, the degenerative neurological disorder is Parkinson's disease.
Yet a further embodiment provides a method for treating hearing disorder by administering a compound of formula (I) or (la) intra-aurally or systemically, wherein the hearing disorders is characterized by melanocyte insufficiency in the inner ear.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
Figure 1 shows comparative effects of forskolin, FK506 and Compound A on melanin production in human melanocytes. Cells cultured for 72 h with the test compounds were assessed for melanin levels by (A) cell pellet appearance in human epidermal melanocytes;light-pigmented (HEMn-LP) cells; or (B) cell lysate melanin levels in in human epidermal melanocytes;dark-pigmented (HEMn-DP) cells. Relative melanin levels are presented as a percentage (%) of the assay result obtained for cells maintained in parallel in the absence of added stimulus. Each symbol indicates the result obtained in an independent experiment. Horizontal bars denote the average of these multiple determinations.
Figure 2 shows the melanin levels in drug-treated melanoma cells. Mouse B16-F10 (A), human G361 (B), and human Mel-Ho (C) were treated with FK506 (20 μΜ), or Compound A (5 μΜ) for 24 hours or 48 hours. Cells were harvested and lysed followed by assays to determine tyrosinase activity and melanin levels. Cells treated with DMSO were served as negative controls. The data shown in (A) and (B) are averages of melanin levels from at least 2 repeated experiments.
Figure 3 shows that Compound A was capable of stimulating tyrosinase activity in HEMn-DP, HEMn-LP and HEMa-LP. Melanocytes were cultured for 72 h with different concentrations of Compound A and cell extracts subsequently prepared for tyrosinase activity determinations. Results are given as a percentage (%) of the assay result obtained for untreated control cells. Symbols indicate the result from each independent experiment. Horizontal bars denote the overall average of these determinations.
Figure 4 shows the tyrosinase activities in drug-treated cells. B16-F10 (A), G361 (B), and Mel-Ho (C) were treated with FK506 (20 μΜ), or Compound A (5 μΜ) for 24 hours or 48 hours. Cells were harvested and lysed followed by assays to determine tyrosinase activity and melanin levels. Cells treated with DMSO served as negative controls. The data shown in (A) and (B) are averages of tyrosinase activity from at least 2 repeated experiments.
Figure 5 shows that an extended culture of HEMn-LP widens the melanogenesis-stimulating concentration range of Compound A. Cells were cultured for 6 days in 75 cm2 flasks with test compounds as indicated and subsequently assessed for tyrosinase activity, melanin levels and cell pellet appearance.
Figure 6 shows the cell morphologies of melanoma cells treated with Compound A. Mouse B16-F10 (A), human G361 (B), and human Mel-Ho (C) melanoma cells were treated with Compound A for 24 or 48 h. DMSO (0.1 %) was used as a negative control. Pictures were taken to show cell morphological changes induced by Compound A. Pictures shown were representatives from at least two experiments.
Figure 7 shows the dendrite counts in B16-F10 Cells. B16-F10 cells were treated with DMSO (0.1 %), FK506 (25 μΜ), or Compound A (5 μΜ) for 24 hours. Fifty cells for each treatment group were sampled. The number of cells with certain numbers of dendrites was counted. The graph shown is the average of dendrite counts from two repeated experiments.
Figure 8 shows that Compound A increases human neonatal melanocyte dendrite numbers and dendrite branching. HEMn-DP (A-D) and HEMn-LP (E-G) were treated with test compounds for 72 h. Compound A was added at 5 μΜ while forskolin and FK506 were present at 20 μΜ and 25 μΜ, respectively. One hundred cells in each treatment group were enumerated microscopically for mean primary dendrite numbers (B, E) and the proportion of cells with 2-3, 4-7 or≥ 8 dendrites per cell (C, F). The percentage of cells exhibiting branched dendrites was also determined (D, G). Cells not exposed to the test compounds served as controls.
Figure 9 shows the expression levels of the melanogenesis-regulating factors tyrosinase, microphthalmia-associated transcription factor (MITF), tyrosinase- related protein-1 (TRP1 ), and TRP2 in drug-treated cells. Mouse B16-F10 melanoma cells (A) and human G361 melanoma cells (B) were treated with forskolin (20 μΜ), FK506 (20 μΜ), or Compound A (5 μΜ) for 24 or 48 hours. Cell lysates were prepared followed by western blotting to examine the protein levels of tyrosinase, MITF, TRP1 , and TRP2. Data shown are representative of experiments repeated 3 times.
Figure 10 shows the effect of Compound A on viability of HEMn-LP in vitro. Cell viability was assessed by the colorimetric MTS assay. Results are given as a percentage (%) of the assay determination obtained for untreated cells maintained in parallel. Mean values with standard deviations are shown. Similar effects were observed in two other experiments performed.
Figures 1 1A-1 1 C show the effects of Compounds A-F on melanogenesis-related parameters. B16-F10 cells were treated with forskolin (25 μΜ), FK506 (20 μΜ), Compound A (5 μΜ), Compound B (10 μΜ), Compound C (10 μΜ), Compound D (5 μΜ), Compound E (1 μΜ), or Compound F (1 μΜ) were administered to the B16-F10 cells for 24 h or 48 h. Dendrite counting (A) assays for tyrosinase activity and melanin levels (B), as well as the expression levels of tyrosinase and MITF (C) were examined in drug treated cells. DMSO was used as a negative control. DETAILED DESCRIPTION
As discussed herein, pigmentation-enhancing agents have the potential to reduce both photodamage and skin cancer incidence as well as restore pigment in conditions such as vitiligo. Thus, compounds which stimulate multiple aspects of the pigmentation machinery including MITF activation/expression, tyrosinase
levels/activity, melanin synthesis, and melanocyte dendricity are preferred. Disclosed herein are a class of small molecules that are capable of inducing melanogenesis and pigmentation. In particular, these compounds and their corresponding pharmaceutical and cosmeceutical compositions stimulate a number of melanogenesis parameters, including dendrite formation, melanin production, enzyme activities and expression.
DEFINITIONS
Certain chemical groups named herein may be preceded by a shorthand notation indicating the total number of carbon atoms that are to be found in the indicated chemical group. For example; C7-Ci2alkyl describes an alkyl group, as defined below, having a total of 7 to 12 carbon atoms, and C4-Ci2cycloalkylalkyl describes a cycloalkylalkyl group, as defined below, having a total of 4 to 12 carbon atoms. The total number of carbons in the shorthand notation does not include carbons that may exist in substituents of the group described.
In addition to the foregoing, as used in the specification and appended claims, unless specified to the contrary, the following terms have the meaning indicated:
"Amino" refers to the -NH2 radical.
"Cyano" refers to the -CN radical.
"Hydroxy" refers to the -OH radical.
"Imino" refers to the =N H substituent.
"Nitro" refers to the -N02 radical.
"Oxo" refers to the =0 substituent.
"Thioxo" refers to the =S substituent.
"Trifluoromethyl" refers to the -CF3 radical.
"Alkyl" refers to a straight or branched hydrocarbon chain radical consisting solely of carbon and hydrogen atoms, containing no unsaturation, having from one to twelve carbon atoms, preferably one to eight carbon atoms or one to six carbon atoms, and which is attached to the rest of the molecule by a single bond, e.g., methyl, ethyl, n-propyl, 1 -methylethyl (/so-propyl), n-butyl, n-pentyl, 1 , 1 -dimethylethyl (f-butyl), 3-methylhexyl, 2-methylhexyl, and the like. Unless stated otherwise specifically in the specification, an alkyl group may be unsubstituted or substituted by one of the following groups: alkyl, alkenyl, halo, haloalkenyl, cyano, nitro, aryl, cycloalkyl, heterocyclyl, heteroaryl, oxo,
trimethylsilanyl, -OR14, -OC(0)-R14, -N(R14)2, -C(0)R14, -C(0)OR14, -C(0)N(R14)2, -N(R1 4)C(0)OR16, -N(R14)C(0)R16, -N(R14)S(0)tR16 (where t is 1 to 2), -S(0)tOR16 (where t is 1 to 2), -S(0)pR16 (where p is 0 to 2), and -S(0)tN(R14)2 (where t is 1 to 2) where each R14 is independently hydrogen, alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl; and each R16 is alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl. "Alkenyl" refers to a straight or branched hydrocarbon chain radical consisting solely of carbon and hydrogen atoms, containing at least one C=C unsaturation, having from one to twelve carbon atoms, preferably one to eight carbon atoms or one to six carbon atoms, and which is attached to the rest of the molecule by a single bond, e.g., ethenyl (vinyl), allyl, butenyl, pentenyl, and the like. Unless stated otherwise specifically in the specification, an alkyl group may be unsubstituted or substituted by one of the following groups: alkyl, alkenyl, halo, haloalkenyl, cyano, nitro, aryl, cycloalkyl, heterocyclyl, heteroaryl, oxo,
trimethylsilanyl, -OR14, -OC(0)-R14, -N(R14)2, -C(0)R14, -C(0)OR14, -C(0)N(R14)2, -N(R1 4)C(0)OR16, -N(R14)C(0)R16, -N(R14)S(0)tR16 (where t is 1 to 2), -S(0)tOR16 (where t is 1 to 2), -S(0)pR16 (where p is 0 to 2), and -S(0)tN(R14)2 (where t is 1 to 2) where each R14 is independently hydrogen, alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl; and each R16 is alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl.
"Alkylene" or "alkylene chain" refers to a straight or branched divalent hydrocarbon chain linking the rest of the molecule to a radical group, consisting solely of carbon and hydrogen, containing no unsaturation and having from one to twelve carbon atoms, e.g., methylene, ethylene, propylene, n-butylene, and the like. The alkylene chain is attached to the rest of the molecule through a single bond and to the radical group through a single bond. The points of attachment of the alkylene chain to the rest of the molecule and to the radical group can be through one carbon or any two carbons within the chain. Unless stated otherwise specifically in the specification, an alkylene chain may be optionally substituted by one of the following groups: alkyl, alkenyl, halo, haloalkenyl, cyano, nitro, aryl, cycloalkyl, heterocyclyl, heteroaryl, oxo, trimethylsilanyl, -OR14, -OC(0)-R14, -N(R14)2, -C(0)R14, -C(0)OR14, -C(0)N(R14)2, -N(R1 4)C(0)OR16, -N(R14)C(0)R16, -N(R14)S(0)tR16 (where t is 1 to 2), -S(0)tOR16 (where t is 1 to 2), -S(0)pR16 (where p is 0 to 2), and -S(0)tN(R14)2 (where t is 1 to 2) where each R14 is independently hydrogen, alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl; and each R16 is alkyl, haloalkyi, cycloalkyl, cycloalkylalkyl, aryl, aralkyi, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl.
"Aryl" refers to a hydrocarbon ring system radical comprising hydrogen, 6 to 18 carbon atoms and at least one aromatic ring. For purposes of this invention, the aryl radical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may included fused or bridged ring systems. Aryl radicals include, but are not limited to, aryl radicals derived from aceanthrylene, acenaphthylene, acephenanthrylene, anthracene, azulene, benzene, chrysene, fluoranthene, fluorene, as-indacene, s-indacene, indane, indene, naphthalene, phenalene, phenanthrene, pleiadene, pyrene, and triphenylene. Unless stated otherwise specifically in the specification, the term "aryl" or the prefix "ar-" (such as in "aralkyi") is meant to include aryl radicals optionally substituted by one or more substituents independently selected from the group consisting of alkyl, alkenyl, halo, haloalkyi, haloalkenyl, cyano, nitro, aryl, aralkyi, heteroaryl,
heteroarylalkyl, -R15-OR14, -R15-OC(0)-R14, -R15-N(R14)2, -R15-C(0)R14, -R15-C(0)OR14, -R15-C(0)N(R14)2, -R15-N(R14)C(0)OR16, -R15-N(R14)C(0)R16, -R15-N(R14)S(0)tR16 (where t is 1 to 2), -R15-N=C(OR14)R14, -R15-S(0)tOR16 (where t is 1 to 2), -R15-S(0)pR16 (where p is 0 to 2), and -R15-S(0)tN(R14)2 (where t is 1 to 2) where each R14 is independently hydrogen, alkyl, haloalkyi, cycloalkyl, cycloalkylalkyl, aryl, aralkyi, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl; each R15 is independently a direct bond or a straight or branched alkylene or alkenylene chain; and each R16 is alkyl, haloalkyi, cycloalkyl, cycloalkylalkyl, aryl, aralkyi, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl.
"Aralkyi" refers to a radical of the formula -Rb-Rc where Rb is an alkylene chain as defined above and Rc is one or more aryl radicals as defined above, for example, benzyl, diphenylmethyl and the like. The alkylene chain part of the aralkyi radical may be optionally substituted as described above for an alkylene chain. The aryl part of the aralkyi radical may be optionally substituted as described above for an aryl group.
"Cycloalkyl" refers to a stable non-aromatic monocyclic or polycyclic hydrocarbon radical consisting solely of carbon and hydrogen atoms, which may include fused or bridged ring systems, having from three to fifteen carbon atoms, preferably having from three to ten carbon atoms, and which is saturated or unsaturated and attached to the rest of the molecule by a single bond. Monocyclic radicals include, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Polycyclic radicals include, for example, adamantyl, norbornyl, decalinyl, and the like. Unless otherwise stated specifically in the specification, the term "cycloalkyi" is meant to include cycloalkyi radicals which are optionally substituted by one or more substituents independently selected from the group consisting of alkyl, alkenyl, halo, haloalkyi, haloalkenyl, cyano, nitro, oxo, aryl, aralkyi, cycloalkyi, cycloalkylalkyi, heterocyclyl, heterocyclylalkyi, heteroaryl, heteroarylalkyl, -R15-OR14, -R15-OC(0)-R14, -R15-N(R14)2, -R15-C(0)R14, -R15-C(0)OR14, -R15-C(0)N(R14)2, -R15-N(R14)C(0)OR16, -R15-N(R14)C(0)R16, -R15-N(R14)S(0)tR16 (where t is 1 to 2), -R15-N=C(OR14)R14, -R15-S(0)tOR16 (where t is 1 to 2), -R15-S(0)pR16 (where p is 0 to 2), and -R15-S(0)tN(R14)2 (where t is 1 to 2) where each R14 is independently hydrogen, alkyl, haloalkyi, cycloalkyi, cycloalkylalkyi, aryl, aralkyi, heterocyclyl, heterocyclylalkyi, heteroaryl or heteroarylalkyl; each R15 is independently a direct bond or a straight or branched alkylene or alkenylene chain; and each R16 is alkyl, haloalkyi, cycloalkyi, cycloalkylalkyi, aryl, aralkyi, heterocyclyl, heterocyclylalkyi, heteroaryl or heteroarylalkyl.
"Halo" refers to bromo, chloro, fluoro or iodo.
"Haloalkyi" refers to an alkyl radical, as defined above, that is substituted by one or more halo radicals, as defined above, e.g., trifluoromethyl, difluoromethyl, trichloromethyl, 2,2,2-trifluoroethyl, 1 -fluoromethyl-2-fluoroethyl, 3-bromo-2-fluoropropyl, 1 -bromomethyl-2-bromoethyl, and the like. The alkyl part of the haloalkyi radical may be optionally substituted as defined above for an alkyl group.
"Hydroxyalkyl" refers to an alkyl radical, as defined above, that is substituted by one or more hydroxy radicals (-OH), e.g., hydroxymethyl, 2- hydroxyethyl, etc. The alkyl part of the hydroxyalkyl radical may be optionally substituted as defined above for an alkyl group.
"Heterocyclyl" refers to a stable 3- to 18-membered non-aromatic ring radical which consists of two to twelve carbon atoms and from one to six heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur. Unless stated otherwise specifically in the specification, the heterocyclyl radical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may include fused or bridged ring systems; and the nitrogen, carbon or sulfur atoms in the heterocyclyl radical may be optionally oxidized; the nitrogen atom may be optionally quaternized; and the heterocyclyl radical may be partially or fully saturated. Examples of such heterocyclyl radicals include, but are not limited to, dioxolanyl, thienyl[1 ,3]dithianyl,
decahydroisoquinolyl, imidazolinyl, imidazolidinyl, isothiazolidinyl, isoxazolidinyl, morpholinyl, octahydroindolyl, octahydroisoindolyl, 2-oxo-1 ,3-dioxol-4yl,
2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolidinyl, oxazolidinyl, piperidinyl, piperazinyl, 4-piperidonyl, pyrrolidinyl, pyrazolidinyl, quinuclidinyl, thiazolidinyl, tetrahydrofuryl, trithianyl, tetrahydropyranyl, thiomorpholinyl, thiamorpholinyl,
1-oxo-thiomorpholinyl, and 1 , 1-dioxo-thiomorpholinyl. Unless stated otherwise specifically in the specification, the term "heterocyclyl" is meant to include heterocyclyl radicals as defined above which are optionally substituted by one or more substituents selected from the group consisting of alkyl, alkenyl, halo, haloalkyl, haloalkenyl, cyano, oxo, thioxo, nitro, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl,
heterocyclylalkyl, heteroaryl,
heteroarylalkyl, -R15-OR14, -R15-OC(0)-R14, -R15-N(R14)2, -R15-C(0)R14, -R15-C(0)OR14, -R15-C(0)N(R14)2, -R15-N(R14)C(0)OR16, -R15-N(R14)C(0)R16, -R15-N(R14)S(0)tR16
(where t is 1 to 2), -R15-N=C(OR14)R14, -R15-S(0)tOR16 (where t is 1 to 2), -R15-S(0)pR16 (where p is 0 to 2), and -R15-S(0)tN(R14)2 (where t is 1 to 2) where each R14 is independently hydrogen, alkyl, alkenyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl; each R15 is independently a direct bond or a straight or branched alkylene or alkenylene chain; and each R16 is alkyl, alkenyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl,
heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl.
"/V-heterocyclyl" refers to a heterocyclyl radical as defined above containing at least one nitrogen and where the point of attachment of the heterocyclyl radical to the rest of the molecule is through a nitrogen atom in the heterocyclyl radical. An /V-heterocyclyl radical may be optionally substituted as described above for heterocyclyl radicals.
"Heterocyclylalkyi" refers to a radical of the formula -Rb h where R is an alkylene chain as defined above and Rh is a heterocyclyl radical as defined above, and if the heterocyclyl is a nitrogen-containing heterocyclyl, the heterocyclyl may be attached to the alkylene chain at the nitrogen atom. The alkylene chain of the heterocyclylalkyi radical may be optionally substituted as defined above for an alkylene chain. The heterocyclyl part of the heterocyclylalkyi radical may be optionally substituted as defined above for a heterocyclyl group.
"Heteroaryl" refers to a 5- to 14-membered ring system radical comprising hydrogen atoms, one to thirteen carbon atoms, one to six heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur, and at least one aromatic ring. For purposes of this invention, the heteroaryl radical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may include fused or bridged ring systems; and the nitrogen, carbon or sulfur atoms in the heteroaryl radical may be optionally oxidized; the nitrogen atom may be optionally quaternized.
Examples include, but are not limited to, azepinyl, acridinyl, benzimidazolyl, benzthiazolyl, benzindolyl, benzodioxolyl, benzofuranyl, benzooxazolyl, benzothiazolyl, benzothiadiazolyl, benzo[£>][1 ,4]dioxepinyl, 1 ,4-benzodioxanyl, benzonaphthofuranyl, benzoxazolyl, benzodioxolyl, benzodioxinyl, benzopyranyl, benzopyranonyl, benzofuranyl, benzofuranonyl, benzothienyl (benzothiophenyl), benzotriazolyl, benzo[4,6]imidazo[1 ,2-a]pyridinyl, carbazolyl, cinnolinyl, dibenzofuranyl,
dibenzothiophenyl, furanyl, furanonyl, isothiazolyl, imidazolyl, indazolyl, indolyl, indazolyl, isoindolyl, indolinyl, isoindolinyl, isoquinolyl, indolizinyl, isoxazolyl, naphthyridinyl, oxadiazolyl, 2-oxoazepinyl, oxazolyl, oxiranyl, 1 -oxidopyridinyl,
1-oxidopyrimidinyl, 1-oxidopyrazinyl, 1-oxidopyridazinyl, 1-phenyl-1 H-pyrrolyl, phenazinyl, phenothiazinyl, phenoxazinyl, phthalazinyl, pteridinyl, purinyl, pyrrolyl, pyrazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrrolyl, quinazolinyl,
quinoxalinyl, quinolinyl, quinuclidinyl, isoquinolinyl, tetrahydroquinolinyl, thiazolyl, thiadiazolyl, triazolyl, tetrazolyl, triazinyl, and thiophenyl (i.e. thienyl). Unless stated otherwise specifically in the specification, the term "heteroaryl" is meant to include heteroaryl radicals as defined above which are optionally substituted by one or more substituents selected from the group consisting of alkyl, alkenyl, alkoxy, halo, haloalkyi, haloalkenyl, cyano, oxo, thioxo, nitro, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl,
heteroarylalkyl, -R15-OR14, -R15-OC(0)-R14, -R15-N(R14)2, -R15-C(0)R14, -R15-C(0)OR14, -R15-C(0)N(R14)2, -R15-N(R14)C(0)OR16, -R15-N(R14)C(0)R16, -R15-N(R14)S(0)tR16 (where t is 1 to 2), -R15-N=C(OR14)R14, -R15-S(0)tOR16 (where t is 1 to 2), -R15-S(0)pR16 (where p is 0 to 2), and -R15-S(0)tN(R14)2 (where t is 1 to 2) where each R14 is independently hydrogen, alkyl, alkenyl, haloalkyi, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl; each R15 is independently a direct bond or a straight or branched alkylene or alkenylene chain; and each R16 is alkyl, alkenyl, haloalkyi, cycloalkyl, cycloalkylalkyl, aryl, aralkyl,
heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl.
"/V-heteroaryl" refers to a heteroaryl radical as defined above containing at least one nitrogen and where the point of attachment of the heteroaryl radical to the rest of the molecule is through a nitrogen atom in the heteroaryl radical. An N- heteroaryl radical may be optionally substituted as described above for heteroaryl radicals.
"Heteroarylalkyl" refers to a radical of the formula -RbR, where Rb is an alkylene chain as defined above and R, is a heteroaryl radical as defined above. The heteroaryl part of the heteroarylalkyl radical may be optionally substituted as defined above for a heteroaryl group. The alkylene chain part of the heteroarylalkyl radical may be optionally substituted as defined above for an alkylene chain.
"Melanogenesis" refers to the process of producing melanin. On mammalian skin, melanogenesis leads to a long-lasting tan. There are both basal and activated levels of melanogenesis; in general, lighter-skinned people have low basal levels of melanogenesis. As discussed in more detail herein, various embodiments of the present disclosure provide method of stimulating or activating melanogenesis in a mammal in need thereof by administering a compound of Formulae (I) or (la).
Stimulated or activated melanogenesis can restore pigmentation in skin afflicted with pigmentation disorders (as defined herein) or can afford long-lasting tan without the risk of UV exposure.
"Pigmentation disorders or conditions" includes disorders involving excessive, inadequate or absent pigmentation in mammalian skin. In general, the pigmentation disorder or condition that is treated by the claimed compounds or composition are typically disorders of the pigment-producing cells (melanocytes) themselves, which may be reduced in number, absent, hyperactive, inactive or commonly with regional localization. Examples of pigmentation disorders include, without limitation, vitiligo and leukoderma. In particular, for patients afflicted with vitiligo, melanocytes in localized areas are either dead or non-functioning, resulting in patches of non-pigmented skin.
"Restore pigmentation" refers to increasing the amount of pigmentation on skin afflicted with any of the pigmentation disorders or conditions, as defined herein. For conditions such as vitiligo, skin pigmentation under treatment may increase in the non-pigmented patches of skin. However, pigmentation may or may not be restored to the full extent of pigmentation as that of the normal skin surrounding the patches.
"Sunless tanning" refers to causing a tan in a mammalian subject without UV exposure, irrespective of the source of the UV radiation (natural or tanning bed).
"Dermatologically acceptable excipient" includes without limitation any adjuvant, carrier, vehicle, excipient, glidant, sweetening agent, diluent, preservative, dye/colorant, flavor enhancer, surfactant, wetting agent, dispersing agent, suspending agent, stabilizer, isotonic agent, solvent, or emulsifier, including those approved by the United States Food and Drug Administration as being acceptable for dermatological use on humans or domestic animals, or which are known, or are suitable for use in dermatological compositions.
"Penetration enhancers," or "permeation enhancers," refers to substances that promote the diffusion of the therapeutic drugs (e.g., the pyrazole compounds described herein) through the skin barrier. As is known, the skin
(especially stratum corneum) provides a physical barrier to the harmful effects of the external environment. In doing so, it also interferes with the absorption or transdermal delivery of topical therapeutic drugs. They typically act to reduce the impedance or resistance of the skin to allow improved permeation of the therapeutic drugs. In particular, substances which would perturb the normal structure of the stratum corneum are capable of disrupting the intercellular lipid organization, thus reducing its effectiveness as a barrier. These substances could include any lipid material which would partition into the stratum corneum lipids causing a direct effect or any material which would affect the proteins and cause an indirect perturbation of the lipid structure. Furthermore, solvents, such as ethanol, can remove lipids from the stratum corneum, thus destroying its lipid organization and disrupting its barrier function.
Examples of penetration enhancers or barrier function disrupters include, but are not limited to, alcohol enhancers, such as alkanols with one to sixteen carbons, benzyl alcohol, butylene glycol, diethylene glycol, glycofurol, glycerides, glycerin, glycerol, phenethyl alcohol, polypropylene glycol, polyvinyl alcohol, and phenol; amide enhancers, such as /V-butyl-/V-dodecylacetamide, crotamiton, N,N- dimethylformamide, /V,/V-dimethylacetamide, /V-methyl formamide, and urea; amino acids, such as L-a-amino acids and water soluble proteins; azone and azone-like compounds, such as azacycloalkanes; essential oils, such as almond oil, amyl butyrate, apricot kernel oil, avocado oil, camphor, castor oil, 1-carvone, coconut oil, corn oil, cotton seed oil, eugenol, menthol, oil of anise, oil of clove, orange oil, peanut oil, peppermint oil, rose oil, safflower oil, sesame oil, shark liver oil (squalene), soybean oil, sunflower oil, and walnut oil; vitamins and herbs, such as aloe, allantoin, black walnut extract, chamomile extract, panthenol, papain, tocopherol, and vitamin A palmitate; waxes, such as candelilla wax, carnuba wax, ceresin wax, beeswax, lanolin wax, jojoba oil, petrolatum; mixes, such as primary esters of fractionated vegetable oil fatty acids with glycerine or propylene glycol, and interesterified medium chain triglyceride oils; fatty acids and fatty acid esters, such as amyl caproate, butyl acetate, caprylic acid, cetyl ester, diethyl sebacate, dioctyl malate, elaidic acid ethyl caprylate, ethyl glycol palmitostearate, glyceryl beheate, glucose glutamate, isobutyl acetate, laureth-4, lauric acid, malic acid, methyl caprate, mineral oil, myristic acid, oleic acid, palmitic acid, PEG fatty esters, polyoxylene sorbitan monooleate, polypropylene glycols, propylene glycols, saccharose disterate, salicylic acid, sodium citrate, stearic acid, soaps, and caproic-, caprylic-, capric-, and lauric-triglycerides; macrocylics, such as butylated hydroxyanisole, cyclopentadecanolide, cyclodextrins; phospholipid and phosphate enhancers, such as dialkylphosphates, ditetradecyl phosphate, lecithin, 2- pyrrolidone derivatives, such as alkyl pyrrolidone-5-carboxylate esters, pyroglutamic acid esters, /V-methyl pyrrolidone, biodegradable soft penetration enhancers, such as dioxane derivatives and dioxolane derivatives; sulphoxide enhancers, such as dimethyl sulphoxide and decylmethyl sulphoxide; acid enhancers, such as alginic acid, sorbic acid, and succinic acid; cyclic amines; imidazolinones; imidazoles; ketones, such as acetone, dimethicone, methyl ethyl ketone, and pentanedione; lanolin derivatives, such as lanolin alcohol, PEG 16 lanolin, and acetylated lanolin; oxazolines; oxazolindinones; proline esters; pyrroles, urethanes; and surfactants, such as nonoxynols, polysorbates, polyoxylene alcohols, polyoxylene fatty acid esters, sodium lauryl sulfate, and sorbitan monostearate.
"Dermatologically effective amount" refers to that amount of an active ingredient which, when administered dermatologically (i.e., systemically or locally, including, for example, topically, intradermally, intravenously, orally or by use of an implant) to a mammal (e.g., mammalian skin), is sufficient to effect the desired treatment, as defined below, of the disorder or condition of interest in the human. The amount of an active ingredient which constitutes a "dermatologically effective amount" will vary depending on the active ingredient, the disorder or condition and its severity, and the age of the human to be treated, but can be determined routinely by one of ordinary skill in the art having regard to his own knowledge and to this disclosure.
"Stable compound" and "stable structure" are meant to indicate a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture, and formulation into an efficacious therapeutic agent.
"Mammal" includes humans as well as animals.
"Optional" or "optionally" means that the subsequently described event of circumstances may or may not occur, and that the description includes instances where said event or circumstance occurs and instances in which it does not. For example, "optionally substituted aryl" means that the aryl radical may or may not be substituted and that the description includes both substituted aryl radicals and aryl radicals having no substitution. When a functional group is described as "optionally substituted," and in turn, substituents on the functional group are also "optionally substituted" and so on, for the purposes of this invention, such iterations are limited to five, preferably such iterations are limited to two.
"Pharmaceutically acceptable carrier, diluent or excipient" includes without limitation any adjuvant, carrier, excipient, glidant, sweetening agent, diluent, preservative, dye/colorant, flavor enhancer, surfactant, wetting agent, dispersing agent, suspending agent, stabilizer, isotonic agent, solvent, or emulsifier which has been approved by the United States Food and Drug Administration as being acceptable for use in humans or domestic animals.
"Pharmaceutically acceptable salt" includes both acid and base addition salts.
"Pharmaceutically acceptable acid addition salt" refers to those salts which retain the biological effectiveness and properties of the free bases, which are not biologically or otherwise undesirable, and which are formed with inorganic acids such as, but are not limited to, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like, and organic acids such as, but not limited to, acetic acid, 2,2-dichloroacetic acid, adipic acid, alginic acid, ascorbic acid, aspartic acid, benzenesulfonic acid, benzoic acid, 4-acetamidobenzoic acid, camphoric acid, camphor-10-sulfonic acid, capric acid, caproic acid, caprylic acid, carbonic acid, cinnamic acid, citric acid, cyclamic acid, dodecylsulfuric acid, ethane-1 ,2-disulfonic acid, ethanesulfonic acid, 2-hydroxyethanesulfonic acid, formic acid, fumaric acid, galactaric acid, gentisic acid, glucoheptonic acid, gluconic acid, glucuronic acid, glutamic acid, glutaric acid, 2-oxo-glutaric acid, glycerophosphoric acid, glycolic acid, hippuric acid, isobutyric acid, lactic acid, lactobionic acid, lauric acid, maleic acid, malic acid, malonic acid, mandelic acid, methanesulfonic acid, mucic acid, naphthalene-1 ,5- disulfonic acid, naphthalene-2-sulfonic acid, 1-hydroxy-2-naphthoic acid, nicotinic acid, oleic acid, orotic acid, oxalic acid, palmitic acid, pamoic acid, propionic acid, pyroglutamic acid, pyruvic acid, salicylic acid, 4-aminosalicylic acid, sebacic acid, stearic acid, succinic acid, tartaric acid, thiocyanic acid, p-toluenesulfonic acid, trifluoroacetic acid, undecylenic acid, and the like. "Pharmaceutically acceptable base addition salt" refers to those salts which retain the biological effectiveness and properties of the free acids, which are not biologically or otherwise undesirable. These salts are prepared from addition of an inorganic base or an organic base to the free acid. Salts derived from inorganic bases include, but are not limited to, the sodium, potassium, lithium, ammonium, calcium, magnesium, iron, zinc, copper, manganese, aluminum salts and the like. Preferred inorganic salts are the ammonium, sodium, potassium, calcium, and magnesium salts. Salts derived from organic bases include, but are not limited to, salts of primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines and basic ion exchange resins, such as ammonia, isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, diethanolamine, ethanolamine, deanol, 2-dimethylaminoethanol,
2-diethylaminoethanol, dicyclohexylamine, lysine, arginine, histidine, caffeine, procaine, hydrabamine, choline, betaine, benethamine, benzathine, ethylenediamine, glucosamine, methylglucamine, theobromine, triethanolamine, tromethamine, purines, piperazine, piperidine, /V-ethylpiperidine, polyamine resins and the like. Particularly preferred organic bases are isopropylamine, diethylamine, ethanolamine,
trimethylamine, dicyclohexylamine, choline and caffeine.
A "pharmaceutical composition" refers to a formulation of a compound of the invention and a medium generally accepted in the art for the delivery of the biologically active compound to mammals, e.g., humans. Such a medium includes all pharmaceutically acceptable carriers, diluents or excipients therefor.
"Therapeutically effective amount" refers to that amount of a compound of the invention which, when administered to a mammal, preferably a human, is sufficient to effect treatment of the disease or condition of interest in a mammal, preferably a human, having the disease or condition. The amount of a compound of the invention which constitutes a "therapeutically effective amount" will vary depending on the compound, the disease or condition and its severity, the manner of
administration, and the age of the mammal to be treated, but can be determined routinely by one of ordinary skill in the art having regard to his own knowledge and to this disclosure. Preferably, for purposes of this invention, a "therapeutically effective amount" is that amount of a compound of invention which is sufficient to stimulate melanogenesis to address certain pigmentation disorders. "Therapeutically effective amount" may differ from "cosmetically effective amount" in that the latter does not necessarily seek to address a pigmentation disorder. Rather, cosmetically effective amount of the claimed compound or composition refers to an amount that will effect a heightened level of melanogenesis (tanning) on normal skin. Thus, cosmetically effective amount is largely determined by aesthetics and personal preference.
"Treating" or "treatment", as used herein, covers the treatment of the disease or condition of interest in a mammal, preferably a human, and includes:
(i) preventing the disease or condition from occurring in the mammal;
(ii) inhibiting the disease or condition in the mammal, i.e., arresting its development;
(iii) relieving the disease or condition in the mammal, i.e., causing regression of the disease or condition; or
(iv) relieving the symptoms of the disease or condition in the mammal, i.e., relieving the symptoms without addressing the underlying disease or condition; or
As used herein, the terms "disease" and "condition" may be used interchangeably or may be different in that the particular malady or condition may not have a known causative agent (so that etiology has not yet been worked out) and it is therefore not yet recognized as a disease but only as an undesirable condition or syndrome, wherein a more or less specific set of symptoms have been identified by clinicians.
The compounds of the invention, or their pharmaceutically acceptable salts may contain one or more asymmetric centers and may thus give rise to enantiomers, diastereomers, and other stereoisomeric forms that may be defined, in terms of absolute stereochemistry, as (R)- or (S)- or, as (D)- or (L)- for amino acids. The present invention is meant to include all such possible isomers, as well as their racemic and optically pure forms. Optically active (+) and (-), (/?)- and (S)-, or (D)- and (L)- isomers may be prepared using chiral synthons or chiral reagents, or resolved using conventional techniques, for example, chromatography and fractional crystallization. Conventional techniques for the preparation/isolation of individual enantiomers include chiral synthesis from a suitable optically pure precursor or resolution of the racemate (or the racemate of a salt or derivative) using, for example, chiral high pressure liquid chromatography (HPLC). When the compounds described herein contain olefinic double bonds or other centers of geometric asymmetry, and unless specified otherwise, it is intended that the compounds include both E and Z geometric isomers. Likewise, all tautomeric forms are also intended to be included.
A "stereoisomer" refers to a compound made up of the same atoms bonded by the same bonds but having different three-dimensional structures, which are not interchangeable. The present disclosure contemplates various stereoisomers and mixtures thereof and includes "enantiomers," which refers to two stereoisomers whose molecules are nonsuperimposeable mirror images of one another.
EMBODIMENTS OF THE INVENTION
As discussed in further detail and in connection with the Examples, it is demonstrated herein that the claimed compounds and compositions are capable of stimulating or activating one or more parameters related to melanogenesis. These parameters include, for example, melanin production, which is a direct result of melanogenesis. Other cellular events that may be indicative of melanogenesis include, for example, enhanced dendrite formation, elevations of the activities of the key enzymes involved in the melanogenesis pathway and/or the expression of the same. Thus, the claimed compounds and compositions are effective in stimulating
melanogenesis at a rate comparable to UV radiation, but without the risks of cellular damage associated with UV exposure.
Disclosed herein include a method of stimulating melanogenesis in a mammal in need thereof, the method comprising administering to the mammal a pharmaceutically effective amount of a compound of Formula (I):
Figure imgf000027_0001
wherein,
m is 0, 1 , 2, or 3;
Ri is hydrogen, alkyl, haloalkyi, alkenyl, aralkyi or aryl;
R2 is hydrogen, alkyl, haloalkyi, alkenyl, aralkyi or aryl;
or Ri and R2 together with the nitrogen to which they are both attached, form an
optionally substituted N-heterocyclyl or an optionally substituted N-heteroaryl;
R3 is alkyl, alkenyl, aralkyi or aryl;
R4 is alkyl, alkenyl, aralkyi or aryl;
or R3 and R4 together with the nitrogen to which they are both attached, form an
optionally substituted N-heterocyclyl or an optionally substituted N-heteroaryl; each R5 is the same or different and independently alkyl, halo, haloalkyi, aralkyi, heterocyclylalkyl, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7, or -C(0)N(R6)R7;
R6 is hydrogen, alkyl, hydroxyalkyl, aralkyi or aryl;
R7 is hydrogen or alkyl; or
R6 and R7 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl.
In various embodiments, at least one R5 of compounds of Formula (I) is an electron-withdrawing group, including, for example, halo, nitro,
cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7, -C(0)N(R6)R7.
In a particular embodiment, R5 of compounds of Formula (I) is -S(0)2-N(R6)R7. In preferred embodiments, R5 is -S(0)2-NH(R6), wherein R6 is alkyl or hydroxyalkyl. In further embodiments, m is 1 , R5 is -S(0)2-NH(R6), wherein R6 is alkyl or hydroxyalkyl, and R5 located at a position meta to the azo moiety of a compound of Formula (I). In various embodiments, Ri and R2 are both hydrogens.
In other embodiments, R3 and R4 are each independently alkyl or aralkyl.
In further embodiments, R3 and R4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl. In various further embodiments, the optionally substituted /V-heterocyclyl is optionally substituted piperazinyl, morpholinyl, pyrrolidinyl, or imidazolidinyl.
A further embodiment provides a method of stimulating melanogenesis in a mammal in need thereof by administering a pharmaceutically effective amount of a compound of Formula (la):
Figure imgf000028_0001
wherein,
n is 0, 1 , or 2;
Ri is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
R2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
or Ri and R2 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
R3 is alkyl, alkenyl, aralkyl or aryl;
R4 is alkyl, alkenyl, aralkyl or aryl;
or R3 and R4 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl;
R6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl;
R7 is hydrogen or alkyl; or
R6 and R7 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl, and each R8 is the same or different and independently alkyl, halo, haloalkyl, aralkyl, heterocyclylalkyl, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7,
or -C(0)N(R6)R7.
In various embodiments, Ri and R2 are both hydrogens.
In other embodiments, R3 and R4 are each independently alkyl or aralkyl.
In further embodiments, R3 and R4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl. In various further embodiments, the optionally substituted /V-heterocyclyl is optionally substituted piperazinyl, morpholinyl, pyrrolidinyl, or imidazolidinyl.
In a more specific embodiment, the method of stimulating melanogenesis in a mammal in need thereof comprises administering to the mammal a pharmaceutically effective amount of a compound of Formulae (I) or (la), wherein the compound is:
3-[/V-(3-amino-5-methylbenzylaminopyrazol-4-ylidene)-hydrazino]-/\/- methyl-benzenesulfonamide;
3-[/V-(3-amino-5-methylbenzylaminopyrazol-4-ylidene)-hydrazino]-/\/- ethyl-benzenesulfonamide;
3-[/V-(3-amino-5-methylbenzylaminopyrazol-4-ylidene)-hydrazino]-/\/-(2- hydroxyethyl)-benzenesulfonamide; or
3-[/V-(3-amino-5-(4-phenoxycarbonylpiperazin-1 -yl)-pyrazol-4-ylidene)- hydrazino]-/V-ethyl-benzenesulfonamide .
In addition to providing sun protection, melanogenesis stimulation may be suitable for treating a number of pigmentation disorders, which results in increased pigmentation or restoration of pigmentation. Furthermore, although melanin is most prevalent in skin, it is also present in hair, the pigmented tissue underlying the iris of the eye, the stria vascularis of the inner ear, the brain tissues and neurons
(neuromelanin), among others. Lower levels of melanin in these tissues have been linked to certain disorders. Thus, the following embodiments are directed to stimulating melanogenesis in various, specific tissues, organ, or pigment-bearing cells. Sun Protection
Of the method of stimulating melanogenesis in a mammal in need thereof, as set forth above in the Summary of the Invention, one embodiment of this method is wherein stimulating melanogenesis includes tanning. In one particular embodiment, the mammal has normal pigmentation and is in need of tanning in the absence of UV exposure.
In a further embodiment, the compounds of formula (I) or (la) could be applied to a person at risk of experiencing polymorphic light eruption, which is a skin irritation caused by sunlight. Typically, 5-20% of fair skinned populations can be affected, but it can occur in any skin type. It is more common in females than in males.
Compounds of formula (I) or (la) may also be useful to treat other sunlight-related disorders such as solar urticaria, which is photodermatosis
characterized by pruritus, stinging, erythema, and weal formation after sun or sun-like light exposure. The disorder may be caused by an antigen-antibody reaction.
Although intravenous immunoglubin has been used with some success, a less complicated treatment and preferably topical treatment is advantageous. Thus, one embodiment provides treating solar urticaria by topically administering a therapeutically effective amount of a compound of formula (I) or (la).
Compounds of formula (I) or (la) may also provide skin protection for porphyrias, which are the result of defects in enzymes needed at various steps of heme synthesis. Clinical manifestations depend on the biochemical step in which the enzymatic defect occurs. If the enzymatic defects are in the initial steps of the metabolic cascade, early metabolic intermediates will accumulate, resulting in neurologic dysfunction. If the enzymatic defects are in the final steps, sunlight-induced cutaneous lesions (photosensitivity) due to porphyrin accumulation in the skin will develop.
Thus, one embodiment provides treating porphyria by topically administering a therapeutically effective amount of a compound of formula (I) or (la). Pigmentation Disorders
Leukoderma is characterized by light patches on the skin. Vitiligo, an immune mediated condition, is also associated with reduced pigment and nonfunctioning melanocytes in skin patches. Leukoderma is congenital while vitiligo is an acquired condition. Unlike albinism, the more common pigment disorders are not disorders of melanin quality, but rather of the pigment-producing cells (melanocytes) themselves, which may be reduced in number, absent, hyperactive, inactive or commonly with regional localization.
A further embodiment provides a method of restoring pigmentation in a mammal having a pigmentation disorder, wherein the method comprises administering to the mammal a therapeutically effective amount of a compound of Formulae (I) or (la).
Of the method of restoring pigmentation, as set forth above in the Summary of the Invention, one embodiment of this method is wherein the pigmentation disorder or condition is selected from the group consisting of vitiligo and leukoderma.
Another embodiment of this method is wherein the dermatological disorder is vitiligo.
Another embodiment of this method is wherein the dermatological disorder is leukoderma.
In another embodiment provides treating light patches on mammalian skin by topically administering a therapeutically effective amount of a compound of formula (I) or (la). In further embodiment, the light patches are results of pigmentation disorders such as leukoderma or vitiligo.
Hair Color
Compounds of formula (I) or (la) may be used to restore or change hair pigmentation (e.g., reversal of hair graying). Hair color depends upon the distribution, type and amount of melanin in the middle layer of the hair shaft or cortex. Hair has only two types of pigments: dark (eumelanin) and light (phaeomelanin). They blend together to make up the wide range of hair colors. Without melanin, hair will grey and ultimately turn white. Melanocytes exist at the openings on the skin's surface through which hair grows (follicles). Each hair grows from a single follicle. The process of scalp hair growth includes the anagen stage, when active growth occurs and can last from 2- 7 years. At any given moment 80-85% of the hair is in the anagen phase. The catagen stage is the phase during which hair growth begins to "shut down" and stop activity. It generally lasts 10- 20 days. During the telogen stage hair growth is completely at rest and the hair fiber falls out. At any given time, 10-15 % of our hair is in the telogen phase, which generally lasts 100 days for scalp hair. After the telogen phase, the hair growth process starts again at the anagen phase.
As the hair is being formed, melanocytes inject pigment (melanin) into cells containing keratin protein, which is the key component that makes up mammalian hair, skin, and nails. Throughout the years, melanocyctes continue to inject pigment into the hair's keratin, until aging reduces the production and/or injection of melanin.
In addition to the aging process, genetics also plays a role in graying hair (especially premature graying). In particular, genes regulate the exhaustion of the pigmentary potential of each individual hair follicle. This occurs at different rates in different hair follicles.
It has also been suggested that a failure of melanocyte stem cells (MSC) to maintain the production of melanocytes could cause graying in hair. See, Nishimura, et al. Science 307: 5710 pp. 720-724 (2005). This failure of MSC maintenance may result in the breakdown of signals that produce hair color.
Thus, one embodiment provides restoring hair color by topically administering a therapeutically effective amount of a compound of formula (I) or (la).
Compounds of formula (I) or (la) may be formulated into a formulation suitable for application to the human scalp, and applied on a daily or twice daily basis. The follicular melanocytes are thus exposed to the melanogenesis-stimulating effect of the compounds. For ease of application, the formulation may be in the form of a solution, aerosol, foam, cream, gel, and the like. Degenerative Neurological Disorders
Neuromelanin is the dark pigment present in pigment-bearing neurons of certain deep brain nuclei. Both the substantia nigra and locus coeruleus can be easily identified grossly at the time of autopsy because of their dark pigmentation. In humans, these nuclei are not pigmented at the time of birth, but develop pigmentation during maturation to adulthood.
Although the functional nature of neuromelanin is unknown in the brain, the pigment is made from oxyradical metabolites of monoamine neurotransmitters including dopamine and norepinephrine.
While the level of neuromelanin generally becomes higher throughout life in most people, the loss or lack of pigmented neurons from specific nuclei is seen in a variety of neurodegenerative diseases, including Parkinson's disease. In Parkinson's disease, there is a massive loss of dopamine-producing pigmented neurons in the substantia nigra (Zecca, Luigi; et al. "The absolute concentration of nigral
neuromelanin, assayed by a new sensitive method, increases throughout the life and is dramatically decreased in Parkinson's disease". FEBS Letters 510 (3): 216-220, (2002). A review of the current understanding of the role and biochemistry of melanins in neurology is provided by Vincent J. H., Pigment Cell Melanoma Res. 22(1 ): 10-1 1 (2009).
Thus, a further embodiment provides a method for treating a
degenerative neurological disorder by locally or systemically administering a pharmaceutical composition comprising a compound of formula (I) or (la) in an amount effective in stimulating neuromelanin synthesis. In a particular embodiment, the degenerative neurological disorder is Parkinson's disease. Hearing Disorders
Hearing disorders (including age-related and noise-induced hearing loss) may develop as a part of the aging process. However, hearing disorders are more prevalent and could occur prematurely in individuals with pigmentation disorders. It has been observed that melanin precursors are capable of preventing premature age-related and noise-induced hearing loss in albino mice. See, Murillo-Cuesta S. et al. Pigment Cell Melanoma Res. 23(1 ):72-83 (2010). Furthermore, a link has been observed between the absence of strial melanin with age-associated marginal cell loss and endocochlear potential decline. See, Ohlemiller K.K. et al., Hear Res. 249(1-2):1- 14 (2009).
Thus, in yet another embodiment, the compounds of formula (I) or (la) may be applied intra-aurally or systemically for prevention or treatment of hearing disorders characterized by melanocyte insufficiency in the inner ear.
Routes of Administration
Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered topically.
Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered subcutaneously.
Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered systemically.
Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered orally.
Another embodiment of this method is wherein the pharmaceutical composition is a dermatological composition and the pharmaceutically acceptable excipient is a dermatologically acceptable excipient.
Another embodiment of this method is wherein the pharmaceutical composition is a systemic composition.
Another embodiment of this method is wherein the pharmaceutical composition is an oral composition.
Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered topically. Compounds of formula (I) or (la) may also be delivered in a
subcutaneous depot or implant.
Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered systemically (including injection).
Another embodiment of this method is wherein the therapeutically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt thereof, is administered orally.
In one specific embodiment, compounds of formula (I) or (la) are formulated into a table tablet containing one adult dose, to be sold as a prophylactic against sunburn. The user would ingest one to three tablets per day, for example, and experience an increase in melanogenesis which would allow them to enjoy sunlight with less risk of skin damage.
Another embodiment of this method is wherein the pharmaceutical composition is a dermatological composition and the pharmaceutically acceptable excipient is a dermatologically acceptable excipient.
Another embodiment of this method is wherein the pharmaceutical composition is a systemic composition.
Another embodiment of this method is wherein the pharmaceutical composition is an oral composition.
Yet a further embodiment provides a compound of Formula (la):
Figure imgf000035_0001
wherein,
n is 0, 1 , or 2;
Ri is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl; R2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
or R-i and R2 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl; R3 is alkyl, alkenyl, aralkyl or aryl;
R4 is alkyl, alkenyl, aralkyl or aryl;
or R3 and R4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl; R6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl;
R7 is hydrogen or alkyl; or
R6 and R7 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl, and
each R8 is the same or different and independently alkyl, halo, haloalkyl, aralkyl, heterocyclylalkyl, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7, or -C(0)N(R6)R7.
provided that, the compound of Formula (la) is not:
4-[/V-(3-amino-5-pyrrolidin-1-yl-pyrazol-4-ylidene)-hydrazino]-benzenesulfonamide; 4-{/V'-[3-amino-5-(4-methylpiperazin-1-yl)-pyrazol-4-ylidene]-hydrazino}- benzenesulfonamide;
3-[/V -(3-amino-5-pyrrolidin-1-yl-pyrazol-4-ylidene)-hydrazino]-/V-methyl- benzenesulfonamide;
3-[/V-(3-amino-5-pyrrolidin-1-yl-pyrazol-4-ylidene)-hydrazino]-benzenesulfonamide; 3-[/V-(3-amino-5-dimethylamino-pyrazol-4-ylidene)-hydrazino]-benzenesulfonamide; 3-[/V-(3-amino-5-dimethylamino-pyrazol-4-ylidene)-hydrazino]-/V-methyl- benzenesulfonamide;
3-[/V-(3-amino-5-morpholin-4-yl-pyrazol-4-ylidene)-hydrazino]-benzenesulfonamide; 3-[/V-(3-amino-5-morpholin-4-yl-pyrazol-4-ylidene)-hydrazino]-/V-methyl- benzenesulfonamide; or
3-[/V -(3-amino-5-morpholin-4-yl-pyrazol-4-ylidene)-hydrazino]-/V-(2-hydroxyethyl)- benzenesulfonamide.
In various embodiments, Ri and R2 are both hydrogens. In other embodiments, R3 and R4 are each independently alkyl or aralkyl.
In further embodiments, R3 and R4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl. In various further embodiments, the optionally substituted /V-heterocyclyl is optionally substituted piperazinyl, morpholinyl, pyrrolidinyl, or imidazolidinyl.
In more specific embodiments, the compound of Formula (la) is:
3-[/V-(3-amino-5-methylbenzylaminopyrazol-4-ylidene)-hydrazino]-/\/- methyl-benzenesulfonamide;
3-[/V-(3-amino-5-methylbenzylaminopyrazol-4-ylidene)-hydrazino]-/\/- ethyl-benzenesulfonamide;
3-[/V-(3-amino-5-methylbenzylaminopyrazol-4-ylidene)-hydrazino]-/\/-(2- hydroxyethyl)-benzenesulfonamide; or
3-[/V-(3-amino-5-(4-phenoxycarbonylpiperazin-1 -yl)-pyrazol-4-ylidene)- hydrazino]-/V-ethyl-benzenesulfonamide .
A further embodiment provides a pharmaceutical composition comprising a pharmaceutical effective amount of a compound of Formula (la), or a pharmaceutically acceptable salt thereof, and a pharmaceutical acceptable excipient.
Of the pharmaceutical compositions, as set forth above, one embodiment is wherein the pharmaceutical composition is a dermatological composition comprising a dermatologically effective amount of a compound of Formula (la), or a dermatologically acceptable salt thereof, and a dermatologically acceptable excipient.
Another embodiment is wherein the dermatological composition is a gel formulation, an alcoholic gel formulation, a hydroalcoholic gel formulation, or a cream formulation.
Another embodiment is wherein the pharmaceutical composition is an oral composition comprising a dermatologically effective amount of a compound of formula (I) or (la), or a pharmaceutically acceptable salt, and a pharmaceutically acceptable excipient. PREPARATION OF THE COMPOUNDS OF FORMULA (I) OR (IA)
It is understood that in the following description, combinations of substituents and/or variables of the depicted formulae are permissible only if such contributions result in stable compounds.
It will also be appreciated by those skilled in the art that in the process described below and in the following Preparations and Examples the functional groups of intermediate compounds may need to be protected by suitable protecting groups. Such functional groups include hydroxy, amino, mercapto and carboxylic acid.
Suitable protecting groups for hydroxy include trialkylsilyl or diarylalkylsilyl (e.g., f-butyldimethylsilyl, f-butyldiphenylsilyl or trimethylsilyl), tetrahydropyranyl, benzyl, and the like. Suitable protecting groups for amino, amidino and guanidino include f-butoxycarbonyl, benzyloxycarbonyl, and the like. Suitable protecting groups for mercapto include -C(0)-R8 (where R8 is alkyl, aryl or aralkyl), p-methoxybenzyl, trityl and the like. Suitable protecting groups for carboxylic acid include alkyl, aryl or aralkyl esters.
Protecting groups may be added or removed in accordance with standard techniques, which are well known to those skilled in the art and as described herein.
The use of protecting groups is described in detail in Green, T.W. and P.G.M. Wutz, Protective Groups in Organic Synthesis (1991 ), 2nd Ed.,
Wiley-lnterscience. The protecting group may also be a polymer resin such as a Wang resin or a 2-chlorotrityl chloride resin.
It will also be appreciated by those skilled in the art, although such protected derivatives of compounds of the invention, as described above in the Summary of the Invention, may not possess pharmacological activity as such, they may be administered to a mammal having a disease-state characterized by thrombotic activity and thereafter metabolized in the body to form compounds of the invention which are pharmacologically active. Such derivatives may therefore be described as "prodrugs". All prodrugs of compounds of the invention are included within the scope of the invention. Accordingly, compounds of the invention as set forth in the Summary of the Invention may be prepared by methods disclosed in the literature, herein and/or as summarized in the following Reaction Schemes. The following Preparations
(intermediates, made) and Examples (compounds of the invention, pharmaceutical compositions comprising the compounds and assays demonstrating their utility) are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use the subject invention, and are not intended to limit the scope of what is regarded as the invention. Efforts have been made to ensure accuracy with respect to the numbers used {e.g., amounts, temperature,
concentrations, etc.) but some experimental errors and deviations should be allowed for. Unless otherwise indicated, parts are parts by weight, molecular weight is average molecular weight, temperature is in degrees centigrade; and pressure is at or near atmospheric.
Figure imgf000039_0001
Compounds of formula (a), an optionally substituted aniline, are commercially available, for example, from Aldrich Chemical Co., or may be prepared according to methods known to one of ordinary skill in the art, or by the methods disclosed herein in the Preparations.
In general, compounds of Formula (I) are prepared by first diazotizing a primary amine of formula (a) by treatment with hydrochloric acid and sodium nitrite. The intermediate diazo compound of formula (b) is then treated, in the presence of a base, for example, sodium acetate, with malononitrile (c) to provide a compound of formula (d). The compound of formula (d) is then reacted with a hydrazine (E) to provide diamino precursors (f) of the compounds of Formula (I). Alkylation of one or more hydrogens of the amino groups according to known methods in the art provides compounds of Formula (I).
PHARMACEUTICAL COMPOSITIONS OF THE INVENTION AND ADMINISTRATION
Pharmaceutical compositions comprising a compound of the invention, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient are one aspect of the present invention. These pharmaceutical compositions may be in any form which allows for the active ingredient, i.e., a compound of formula (I) or (la), to be administered to a human in a therapeutically effective amount. For example, the pharmaceutical composition may be in the form of a semi-solid (gel), solid, liquid or gas (aerosol). Typical routes of administration include, without limitation, systemic (including oral and parenteral), topical, buccal, transdermal, sublingual, nasal, rectal, vaginal, and intranasal administration. The term parenteral as used herein includes subcutaneous injections, needle-less injections, intravenous, intramuscular, epidural, intrasternal injection or infusion techniques. Pharmaceutical compositions of the invention are formulated so as to allow the active ingredients contained therein to be bioavailable upon administration of the composition to a human. Pharmaceutical compositions of the invention that will be administered to a human may take the form of one or more dosage units, where for example, a tablet, capsule, cachet or patch may be a single dosage unit, and a container of a pharmaceutical composition of the invention in aerosol form may hold a plurality of dosage units.
In treating dermatological disorders characterized by deficiency or absence of pigmentation, the compound of formula (I) or (la) is preferably administered to the skin (i.e., topically) of the human in need thereof in dermatologically acceptable compositions, as described in more detail below. When such compositions are in use (e.g., when a dermatological composition comprising a compound of formula (I) or (la) and a dermatologically acceptable excipient is placed upon the skin of the human in need thereof), the compound of formula (I) or (la) is in continuous contact with the skin of the patient, thereby effecting treatment.
Any suitable amount of a compound of formula (I) or (la) can be employed in such dermatological compositions, provided the amount employed effectively stimulate melanogenesis and remains stable in the composition over a prolonged period of time. Preferably, the stability is over a prolonged period of time, e.g., up to about 3 years, up to 1 year, or up to about 6 months, which is typical in the manufacturing, packaging, shipping and/or storage of dermatologically acceptable compositions. A compound of formula (I) or (la) can be in solution, partially in solution with an undissolved portion or completely undissolved suspension. A compound of formula (I) or (la) can be present in a dermatological composition of the invention in a concentration range from about 0.001 wt.% to about 80 wt.%, from about 0.001 wt.% to about 50 wt.%, from about 0.001 wt.% to about 25 wt.%, or from about 0.001 wt.% to about 6 wt.% of the dermatological composition. In one embodiment, a compound of formula (I) or (la) can be present in a concentration range of from about 0.001 wt.% to about 10 wt.%, from about 0.1 wt.% to about 10 wt.% or from about 1 .0 wt.% to about 5.0 wt.% of the dermatological composition. In a more specific embodiment, an effective dose may range from 0.01 %-5% of a compound of formula (I) or (la), given 1 - 4 times daily for 2-3 months. In another embodiment of the invention, a dermatological formulation of a compound of formula (I) or (la) to be administered topically contains (by weight) about 3% of a compound of Formulae (I) or (la) in about 40%
dimethylacetamide (DMA) / 30% acetone / 30% ethanol. A dermatological composition of the invention can be in the form of a solution, lotion, foam, gel, cream and/or ointment. Preferably, the dermatological composition will be a topical formulation, for example, a gel, foam, cream or ointment.
A dermatological composition of the invention can contain one or more "lipophilic solvent(s)" that acts as a carrier into the pilosebaceous unit. A lipophilic solvent useful in the invention can be miscible with water and/or lower chain alcohols and have a vapor pressure less than water at 25°C (~ 23.8 mm Hg). A lipophilic solvent useful in the invention can be a glycol, specifically propylene glycol. In particular, the propylene glycol can be from the class of polyethylene glycols, specifically polyethylene glycols ranging in molecular weight from 200 to 20000.
Preferably, the solvent would be part of a class of glycol ethers. More specifically, a lipophilic solvent of the invention would be diethylene glycol monoethyl ether ("DGME") or 2-(2-ethoxyethoxy)ethanol (Transcutol™).
A dermatological composition of the invention can also contain one or more "filler(s)" that has a vapor pressure greater than or equal to 23.8 mm Hg at 25°C. The filler should have a vapor pressure greater than or equal to the lipophilic solvent as to concentrate the compound of formula (I) or (la) on the skin. Preferred concentration range of a single filler or the total of a combination of fillers can be from about 0.1 wt.% to about 10 wt. %, more preferably from about 10 wt. % to about 50 wt.%, more specifically from about 50 wt.% to about 95 wt.% of the dermatological composition. Non-limiting examples for use herein include water and lower alcohols, including ethanol, 2-propanol and n-propanol. More preferably, the filler is water, ethanol and/or 2-propanol. Specifically, the filler would be ethanol and/or water.
A dermatological composition of the invention can also contain one or more "humectant(s)" used to provide a moistening effect. Preferably the humectant remains stable in the composition. Any suitable concentration of a single humectant or a combination of humectants can be employed, provided that the resulting
concentration provides the desired moistening effect. Typically, the suitable amount of humectant will depend upon the specific humectant or humectants employed.
Preferred concentration range of a single humectant or the total of a combination of humectants can be from about 0.1 wt.% to about 70 wt.%, more preferably from about 5.0 wt.% to about 30 wt.%, more specifically from about 10 wt.% to about 25 wt.% of the dermatological composition. Non-limiting examples for use herein include glycerin, polyhydric alcohols and silicone oils. More preferably, the humectant is glycerin, propylene glycol and/or cyclomethicone. Specifically, the filler would be glycerine and/or cyclomethicone.
A dermatological composition of the invention can also contain a gelling agent that increases the viscosity of the final solution. The gelling agent can also act as an emulsifying agent. The present dermatological compositions can form clear gels and soft gels, which upon application to the skin can break down and deteriorate, affording gels that do not dry on the skin. Typically, the concentration and combination of gelling agents will depend on the physical stability of the finished product. Preferred concentration range of a gelling agent can be from about 0.01 wt.% to about 20 wt.%, more preferably from about 0.1 wt.% to about 10 wt.%, more specifically from about 0.5 wt. % to about 5 wt.% of the dermatological composition. Non-limiting examples for use herein include classes of celluloses, acrylate polymers and acrylate
crosspolymers. Preferably, hydroxypropyl cellulose, hydroxymethyl cellulose, Pluronic PF127 polymer, carbomer 980, carbomer 1342 and carbomer 940, more preferably hydroxypropyl cellulose, Pluronic PF127 carbomer 980 and carbomer 1342, more specifically hydroxypropyl cellulose (Klucel® EF, GF and/or HF), Pluronic PF127, carbomer 980 and/or carbomer 1342 (Pemulen® TR-1 , TR-2 and/or Carbopol® ETD 2020).
A dermatological composition of the invention can contain one or more anti-oxidants, radical scavengers, and/or stabilizing agents, preferred concentration range from about 0.001 wt.% to about 0.1 wt.%, more preferably from about 0.1 wt.% to about 5 wt.% of the dermatological composition. Non-limiting examples for use herein include butylatedhydroxytoluene, butylatedhydroxyanisole, ascorbyl palmitate, citric acid, vitamin E, vitamin E acetate, vitamin E-TPGS, ascorbic acid, tocophersolan and propyl gallate. More specifically the anti-oxidant can be ascorbyl palmitate, vitamin E acetate, vitamin E-TPGS, vitamin E or butylatedhydroxytoluene.
A dermatological composition of the invention can also contain preservatives that exhibit anti-bacterial and/or anti-fungal properties. Preservatives can be present in a gelled dermatological composition of the invention to minimize bacterial and/or fungal over its shelf-life. Preferred concentration range of
preservatives in a dermatological composition of the invention can be from about 0.001 wt.% to about 0.01 wt.%, more preferably from about 0.01 wt.% to about 0.5 wt.% of the dermatological composition. Non-limiting examples for use herein include diazolidinyl urea, methylparaben, propylparaben, tetrasodium EDTA, and
ethylparaben. More specifically the preservative would be a combination of
methylparaben and propylparaben.
A dermatological composition can optionally include one or more chelating agents. As used herein, the term "chelating agent" or "chelator" refers to those skin benefit agents capable of removing a metal ion from a system by forming a complex so that the metal ion cannot readily participate in or catalyze chemical reactions. The chelating agents for use herein are preferably formulated at
concentrations ranging from about 0.001 wt.% to about 10 wt.%, more preferably from about 0.05 wt.% to about 5.0 wt.% of the dermatological composition. Non-limiting examples for use herein include EDTA, disodium edeate, dipotassium edeate, cyclodextrin, trisodium edetate, tetrasodium edetate, citric acid, sodium citrate, gluconic acid and potassium gluconate. Specifically, the chelating agent can be EDTA, disodium edeate, dipotassium edate, trisodium edetate or potassium gluconate.
The dermatological compositions of this invention can be provided in any cosmetically suitable form, preferably as a lotion or a cream, but also in an ointment or oil base, as well as a sprayable liquid form (e.g., a spray that includes the claimed compound in a base, vehicle or carrier that dries in a cosmetically acceptable way without the greasy appearance that a lotion or ointment would have when applied to the skin), or pre-loaded towelettes or wipes.
In addition, the dermatological compositions of the invention can include one or more compatible cosmetically acceptable adjuvants commonly used, such as colorants, fragrances, emollients, humectants and the like, as well as botanicals, such as aloe, chamomile and the like.
In topically administering the dermatological compositions of the invention, the skin of the human to be treated can be optionally pre-treated (such as washing the skin with soap and water or cleansing the skin with an alcohol-based cleanser) prior to administration of the dermatological composition of the invention.
In treating pigmentation disorders or conditions characterized by defective, deficient or absent melanocytes, a compound of formula (I) or (la) or a pharmaceutical composition comprising a compound of formula (I) or (la) may also be administered systemically or orally, to the human in need thereof in pharmaceutically acceptable compositions, as described in more detail below.
A pharmaceutical composition of the invention to be orally administered can be prepared by combining a compound of formula (I) or (la) with an appropriate pharmaceutically acceptable carrier, diluent or excipient by standard methods known to one skilled in the art. Pharmaceutical compositions of the invention are formulated so as to allow the compound of formula (I) or (la) contained therein to be bioavailable upon administration of the composition to a human.
A pharmaceutical composition of the invention to be orally administered may be formulated into a powder, granule, compressed tablet, pill, capsule, chewing gum, wafer or the like form. Such a solid composition will typically contain one or more inert diluents or edible carriers. In addition, one or more of the following may be present: binders such as carboxymethylcellulose, ethyl cellulose, microcrystalline cellulose, gum tragacanth or gelatin; excipients such as starch, lactose or dextrins, disintegrating agents such as alginic acid, sodium alginate, Primogel, corn starch and the like; lubricants such as magnesium stearate or Sterotex; glidants such as colloidal silicon dioxide; sweetening agents such as sucrose or saccharin; a flavoring agent such as peppermint, methyl salicylate or orange flavoring; and a coloring agent.
When a pharmaceutical composition of the invention is in the form of a capsule, for example, a gelatin capsule, it may contain, in addition to materials of the above type, a liquid carrier such as polyethylene glycol or oil.
A pharmaceutical composition of the invention to be orally administered may also be in the form of a liquid, for example, an elixir, syrup, solution, emulsion or suspension. The pharmaceutical composition may also optionally contain one or more of a sweetening agent, preservatives, dye/colorant and flavor enhancer. . Liquid pharmaceutical compositions of the invention may also include one or more of the following adjuvants: sterile water, saline solution ( preferably physiological saline solution), Ringer's solution, isotonic sodium chloride, fixed oils such as synthetic mono or diglycerides which may serve as the solvent or suspending medium, polyethylene glycols, glycerin, propylene glycol or other solvents; antibacterial agents such as benzyl alcohol or methyl paraben; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates or phosphates and agents for the adjustment of tonicity such as sodium chloride or dextrose.
A liquid pharmaceutical composition of the invention contains a therapeutically effective amount of a compound of formula (I) or (la) when administered to a human in need thereof. Typically, this amount is at least 0.01 % of a compound of formula (I) or (la) in the composition. This amount may be varied to be between about 0.1 wt.% and about 70% of the total weight of the composition. Preferred oral pharmaceutical compositions contain a compound of formula (I) or (la) at a
concentration range of between about 1.0 wt.% and about 50 wt.% of the oral composition.
A pharmaceutical composition of the invention may include various materials, which modify the physical form of a solid or liquid dosage unit. For example, the composition may include materials that form a coating shell around the active ingredient. The materials that form the coating shell are typically inert, and may be selected from, for example, sugar, shellac, and other enteric coating agents.
Alternatively, the active ingredient may be encased in a gelatin capsule.
A pharmaceutical composition of the invention in solid or liquid form may also include an agent that binds to a compound of formula (I) or (la) and thereby assists in the systemic delivery of the compound of formula (I) or (la). Suitable agents that may act in this capacity include a monoclonal or polyclonal antibody, a protein or a liposome.
Systemic administration of the pharmaceutical compositions of the invention also include administration by injection, e.g., subcutaneous, intravenous, intramuscular, intrathecal or intraperitoneal injection, as well as transdermal, transmucosal, or pulmonary administration and needle-less injection administration.
Useful injectable pharmaceutical compositions include sterile suspensions, solutions or emulsions of the active compound(s) in aqueous or oily vehicles. The compositions may also contain formulating agents, such as suspending, stabilizing and/or dispersing agent. The pharmaceutical compositions for injection may be presented in unit dosage form, e.g., in ampules or in multidose containers, and may contain added preservatives.
Alternatively, the injectable pharmaceutical compositions may be provided in powder form for reconstitution with a suitable vehicle, including but not limited to sterile pyrogen free water, buffer, dextrose solution, etc., before use. To this end, the active compound, i.e., a compound of formula (I) or (la), may be dried by any art-known technique, such as lyophilization, and reconstituted prior to use.
Alternatively, other pharmaceutical delivery systems may be employed for the pharmaceutical compositions of the invention. Liposomes and emulsions are well-known examples of delivery vehicles that may be used to deliver active compound(s) or prodrug(s). Certain organic solvents such as dimethylsulfoxide (DMSO) may also be employed, although usually at the cost of greater toxicity.
The pharmaceutical compositions of the invention may, if desired, be presented in a pack or dispenser device which may contain one or more unit dosage forms containing the active compound(s). The pack may, for example, comprise metal or plastic foil, such as a blister pack. The pack or dispenser device may be
accompanied by instructions for administration.
The pharmaceutical compositions of the invention as set forth above may be prepared by methodology well known in the pharmaceutical art or by the method described herein. See, for example, Remington's Pharmaceutical Sciences, 18th Ed., (Mack Publishing Company, Easton, Pennsylvania, 1990).
The pharmaceutical compositions of the invention are administered to a human in a therapeutically effective amount, which will vary depending upon a variety of factors including the activity of the compound of formula (I) or (la); the metabolic stability and length of action of the compound of formula (I) or (la); the age, body weight, general health, sex, and diet of the human; the mode and time of
administration; the rate of excretion; the drug combination; and the severity of the particular disorder or condition. Generally, a therapeutically effective daily dose of a compound of formula (I) or (la) is (for a 70 kg mammal) from about 0.001 mg/kg (i.e., 0.07 mg) to about 100 mg/kg (i.e., 7.0 gm); preferably a therapeutically effective dose is (for a 70 kg mammal) from about 0.01 mg/kg (i.e., 0.7 mg) to about 50 mg/kg (i.e., 3.5 gm); more preferably a therapeutically effective dose is (for a 70 kg mammal) from about 1 mg/kg (i.e., 70 mg) to about 25 mg/kg (i.e., 1.75 gm).
MELANOGENESIS-RELATED PARAMETERS
It is demonstrated herein that the claimed compounds and compositions are capable of stimulating or activating one or more parameters related to
melanogenesis. These parameters include, for example, melanin production, which is a direct result of melanogenesis. Other cellular events that may be indicative of melanogenesis include, for example, enhanced dendrite formation, elevations of the activities of the key enzymes involved in the melanogenesis pathway and/or the expression of the same.
Notably, dendrite formation (i.e., dendritogenesis) in melanocytes is required for transport of melanosomes to the periphery of melanocytes for subsequent transfer to keratinocytes. Dendrites are branched projections formed from
melanocytes. The dendricity of melanocytes is typically measured by the number and length of the dendrites. Primary dendrites refer to dendrites that extruded directly from the cell body, whereas secondary dendrites originate from primary dendrites and so forth. In human epidermis, one dendritic melanocyte may interact with about 36 keratinocytes to supply these cells with melanin.
UV light is a prominent stimulus of melanocyte dendricity. The initial process of dendrite formation in human melanocytes in response to UV light radiation and keratinocyte-conditioned media has been shown to involve increased formation of microfilaments and actin polymerization. Within 24 hours of irradiation of human melanocyte-keratinocyte co-cultures, melanocytes form long branching dendrites. Melanocyte dendricity can also be induced by UV light in the absence of keratinocytes, although the underlying mechanism is unknown.
UV light radiation can also act indirectly on melanocytes by stimulating the release of keratinocyte-derived factors that in turn regulate melanogenesis. Among the factors secreted by keratinocytes upon UV light exposure, a-melanocyte-stimulating hormone (a-MSH) is a potent endogenous activator of melanogenesis. See, Lin et al. Nature 445: 843-850 (2007), and D'Orazio et al. Nature (2006) 443: 340-344. Other hormones, such as endothelin-1 and nerve growth factor, are also capable of inducing melanocyte dendrite formation. Scott et al. Pigment Cell Res. 15: 322-330(2002). Dendrite extension in mouse B16-F1 melanoma cells in response to keratinocyte- conditioned medium and in melanocytes in response to a-MSH has been shown to require actin assembly. Scott et al. supra.
As demonstrated herein, the claimed compounds and compositions are capable of stimulating dendrite formation in human melanocytes as well as human and mouse melanoma cells within 24 hours of treatment, in the absence of UV radiation. Thus, the claimed compounds and compositions are effective in stimulating
melanogenesis at a rate comparable to UV radiation, but without the risks of cellular damage associated with UV exposure.
It is also demonstrated that the activities of the key enzymes involved in the melanogenesis pathway and/or the expression of the same can be elevated in treatment using the claimed compounds. In particular, the activity of tyrosinase, a rate- limiting enzyme in pigmentation pathway for converting tyrosine to melanin, can be shown to increase in in vitro treatment of melanocytes and melanoma cells with the claimed compounds.
The various embodiments described above can be combined to provide further embodiments.
The following examples are provided merely as illustrative of various aspects of the invention and should not be construed to limit the invention in any way. EXAMPLES
Materials and General Methods
Cell Culture
Human epidermal melanocytes of neonatal light-pigmented (HEMn-LP) and dark-pigmented (HEMn-DP) as well as light-pigmented adult (HEMa-LP) tissue (Cascade Biologies, Portland, OR) were maintained in Medium 254 (Cascade
Biologies) supplemented with human melanocyte growth supplement-2 (Cascade Biologies) at 37°C in a humidified atmosphere under 5% C02. Melanocytes of up to 5 passages were used for experiments. Melanocytes were plated at least 24 h prior to treatment to allow cells to adhere to culture plates or dishes.
Certain melanoma cells are dendritic and contain moderate amounts of melanin, which make them suitable for dendritogenesis and pigmentation studies (Huberman 1979, Busca 1996, Englaro 1998, Oka 2000). Metastatic mouse B16-F10 melanoma (ATCC number CRL-6475) and human G361 melanoma cells (ATCC number CRL-1424) were acquired from the American Type Culture Collection (ATCC). Primary human Mel-Ho melanoma cells (DSMZ number: ACC 62) were obtained from the Deutsche Sommlung con Mikroorganismen end Aelkulturen GmbH (DSMZ). B16- F10 and G361 cells were cultured in Dulbecco's modified Eagle Media
(GIBCO/lnvitrogen) containing 10% fetal bovine serum (FBS, GIBCO). Mel-Ho cells were cultured in RPMI 1640 (GIBCO/lnvitrogen) containing 10% FBS. All cell lines were maintained at 37°C with 5% C02. Growth medium was changed every 2-3 days. At 85% confluency, cells were trypsinized in 1 X trypsin/EDTA and one-tenth of the cells were subcultured.
In vitro Testing
The claimed compounds A-D, as well as compounds E and F were tested in vitro for their potential effects on cell morphology and pigmentation-related changes. Forskolin and FK506 (purchased from Sigma-Aldrich), which are known to affect pigmentation, were also tested for purposes of comparison. Cells were seeded in growth medium at a density of 2x105 to 5x105 cells per well (75%-80% confluency) in 6-well plates and allowed to settle overnight. The following day, cells were treated with forskolin (20 μΜ), FK506 (25 μΜ), Compound A (5 μΜ), Compound B (10 μΜ), Compound C (10 μΜ), Compound D (5 μΜ), Compound E (0.25 μΜ), or Compound F (1 μΜ) for 24 h, 48 h or 72 h. In addition to compounds A-D of Formula (la) compounds E and F were also tested for purpose of comparison. Compounds A-F are shown below in Table 1.
TABLE 1
Figure imgf000051_0001
Figure imgf000052_0001
e test compounds were dissolved in dimethylsulfoxide (DMSO) and subsequently diluted with culture medium. Final DMSO concentrations in cell cultures were 0.1 % or less, levels that did not affect cell viability, tyrosinase activity or melanin levels. Petri dishes with a diameter of 65 mm were used in the majority of studies while 96-well microtiter plates were used in cell viability experiments and 75 cm2 tissue culture flasks were implemented to maximize the melanin signal with HEMn-LP. Cell cultures at the end of experiments typically had achieved 70%-80% confluency.
Untreated cells or cells treated with drug-solvent (0.1 % DMSO) served as controls. At the indicated sampling times, pictures of the cells were taken and whole-cell extracts were prepared for assessment of the melanogenesis-related parameters.
To perform whole cell extracts, medium was removed and the cells were washed once with ice-cold PBS. Cells were lysed in a buffer composed of 20 mM Tris-HCI pH7.4, 150 mM NaCI, 1 % Triton X-100, protease inhibitor cocktail, 75 mM β-glycerol phosphate and 1 mM Na3C04. Supernatants were saved for the tyrosinase assay and pellets were used for melanin determination. Lysate protein levels were determined using the bicinchoninic acid (BCA; Pierce Biotechnology, Inc.) assay. Melanin Determinations
For melanin determinations, approximately 5 x 105 cells were initially lysed in a mixture containing 1 % Triton X-100, 20 mM Tris-HCI pH 7.4, 150 mM NaCI and 5 mM EDTA. To solubilize opaque substances other than melanin, 0.5 ml of ethanol-ether 1 :1 (vol /vol) was added to the cell pellets. Following centrifugation, the precipitate was solubilized in 0.2 ml of 2N NaOH/20% DMSO at 60°C for 2-4 h until full dissolution was achieved. Solution absorbance was measured at 450 nm. Melanin content was normalized to account for protein concentration and expressed as a percentage of the result obtained for control cultures.
Tyrosinase Activity Assay
Tyrosinase activity was determined using a dihydroxyphenylalanine
(DOPA) oxidase activity-assay. The reaction mixture consisted of 150 μΙ of cell lysate and 10 μΙ of 10 mM L-DOPA in PBS. Following 60 min at 37°C, the absorbance of the mixture was measured at an absorbance of 490 nm, corrected for lysate protein concentration and expressed as a percentage of the control result (100%). Cell Morphology and Dendrite Quantification
Cell morphology and dendrite formation (elongated cellular processes) were assessed by phase-contrast photomicrographs of cells in culture plates captured by a Zeiss Axiovert TV100 microscope (Zeiss, Germany) equipped with a Photometries Versarray camera.
For these analyses, the cells were seeded at a density of 9x104 cells per well in six-well plates and treated with the tested compounds for 24, 48, or 72 h. Cells maintained in medium alone and cells treated with 0.1 % DMSO served as assay controls. The cellular dendricity was determined by counting the total number of primary, secondary and tertiary dendrites. Primary dendrites were considered dendrites that extruded directly from the cell body. In order to be included in the count, dendrite length needed to be at least one-third of the cell body diameter. For dendrites to be deemed secondary, these had to originate from a primary dendrite with a length that was at least one-third that of the primary dendrite. Similarly, tertiary dendrites originated from a secondary dendrite with a length that was at least one-third that of the second dendrite. For instance, five non-overlapping images of each treatment well were taken and 20 cells per image field were subjected to dendrite analysis. Protein Expression
To assess tyrosinase, MITF, TRP1 , and TRP2 expression, cell extracts were separated in 12% SDS-polyacrylamide gels and transferred to 0.45 μηη pore-size nitrocellulose membranes for 1 h at 100 volts in transfer buffer containing 20% methanol. The membrane was stained with Ponceau-S to ensure satisfactory protein separation and transfer had occurred. To minimize non-specific antibody binding, membranes were blocked with 5% bovine serum albumin (BSA) in Tris-buffered saline (TBS) with 0.05% Tween-20 (TBS-T) for 1 h at room temperature. Membranes were then incubated with different primary antibodies overnight at 4°C. Antibodies against the following proteins were used: actin (polyclonal; 1 :20,000 dilution; Sigma), tyrosinase (polyclonal; 1 :500 dilution; Santa Cruz), MITF (monoclonal [C5]; 1 :1000 dilution; Abeam), TRP1 (polyclonal; 1 :500 dilution; Santa Cruz), and TRP2 (polyclonal; 1 :500 dilution; Santa Cruz). All antibodies were diluted in TBS-T containing 5% BSA. After primary antibody incubation, the membrane was incubated with anti-goat (1 :10,000 dilution; Santa Cruz) or anti-mouse IgG horseradish peroxidase-linked antibody (1 :10,000 dilution; Cell Signaling) in TBS-T for 1 h at room temperature and subjected to the enhanced chemiluminescence (ECL) detection system (GE
Healthcare Bio-Sciences) and film exposure. Cell Viability Assay
To determine the effects of the tested compounds on cell viability, HEMn-DP were incubated in 96-well microtiter plates with test agents for 72 h. The cell viability assay is based on the conversion of the 3-(4,5-dimethylthiazol-2-yl)-5-(3- carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H- tetrazolium, inner salt (MTS, Promega Corporation, Madison, Wl), by the cellular mitochondrial enzyme succinate- dehydrogenase into a soluble blue-colored formazan product that is measured spectrophotometrically. MTS was added into cell cultures and incubated at 37°C under 5% C02 until sufficient color development was achieved (optical density value of 0.6- 1.0 units). The absorbance of the formazan product was read using a microplate reader set at a wavelength of 490 nm.
EXAMPLE 1
EFFECT OF COMPOUND A ON MELANIN LEVELS
Figure 1 demonstrates that Compound A reproducibly increased melanin levels in HEMn-LP and HEMn-DP as determined by cell pellet appearance (A) or melanin determinations (B), respectively. Similar darkening was observed for cell pellets generated with HEMn-DP following Compound A treatment (data not shown). On average, Compound A increased HEMn-DP melanin levels by 25%-75% in a dose- dependent manner as determined with melanin extraction and spectrophotometry methodologies. As a comparison, Forskolin had no effect on melanin levels while FK506 increased HEMn-DP melanin expression at some test concentrations. It was difficult to determine, however, the melanin levels for HEMn-LP due to the insensitivity of the assay to reliably detect this substance in extracts prepared from these cells using 65-mm sized petri dishes.
Compound A demonstrated similar effects on melanin levels in the melanoma cell lines. As shown in Figure 2, Compound A increased melanin levels 2.8 fold in B16-F10 and 2.7 fold in G361 cells after 48 h, when compared to a control of DMSO treatment. FK506 was also shown to have promoted melanin production in B16-F10 and Mel-Ho cells. Compound A treated Mel-Ho cells did not contain enough melanin to be assayed after 24 h and produced only 1.4 fold more melanin content than the control cells after 48 h. Figure 2(C). It is possible that the Mel-Ho cells have a lower capacity for melanin production or that with drug treatment it might take longer for these cells to achieve similar melanin levels in B16-F10 and G361 cells.
EXAMPLE 2
COMPOUND A I NCREASES MELANOCYTE TYROSINASE ACTIVITY
In further analyses, the activity level of the rate-limiting enzyme
(tyrosinase) in the melanin synthesis pathway was investigated. Responses of primary human melanocytes from three different sources (HEMn-LP, HEMn-DP, HEMa-LP) were evaluated. As shown in Figure 3, an increase in tyrosinase activity of about 200% was evident for cells of all origin treated with Compound A at 5 μΜ for 72 hours. The enzymatic activity was also demonstrated to be concentration dependent. At a concentration of 1 μΜ, little change in tyrosinase activity was observed with Compound A. However, the enzyme activity markedly increased when Compound A was tested at 10 μΜ on HEM-LP and HEM-DP. Highly consistent responses were obtained in different experiments and for cells from different donors.
Similarly, in all three melanoma cell lines, Compound A increased tyrosinase activities. In cells treated by Compound A after 24 h, there was 1.3-, 2.0-, and 1 .5-fold inductions in tyrosinase activity in B16-F10, G361 , and Mel-Ho cells, respectively, in comparison to a DMSO control. Figures 4(A)-4(C). FK506 was also shown to have promoted tyrosinase activity in B16-F10 and Mel-Ho cells.
EXAMPLE 3
EFFECT OF COMPOUND A ON MELANOGENESIS IN EXTENDED CULTURE
To determine if Compound A at lower doses might also stimulate melanogenesis, a longer incubation period was evaluated with HEMn-LP. As shown in Figure 5, although no increase in tyrosinase activity was detected at Compound A at less than 5 μΜ after 3 days of culture, melanin determinations and cell pellet assessments indicated a stimulation of melanogenesis-related parameters could be produced at Compound A concentrations of 0.5 μΜ and 1 μΜ. DMSO at 0.1 % and FK506 at 20 μΜ were tested in parallel over the 6-day culture period but these treatments did not affect tyrosinase activity or melanin levels in these cells.
EXAMPLE 4
EFFECTS OF COMPOUND A ON CELL MORPHOLOGY To investigate the action of the claimed compounds on melanogenesis, mouse B16-F10, human G361 , and human Mel-Ho melanoma cells were treated with forskolin, FK506, or Compound A in normal growth medium. Compared to the DMSO control, Compound A induced morphological changes in all three cell lines, in which the cell bodies became rounder and more primary and secondary dendrites were formed. See, Figure 6 (A-C). Among the three melanoma cell lines investigated, B16- F10 showed the most profound morphological changes (A). For G361 cells, the increase in dendricity was mostly observed in cells close to each other rather than in single cells (B).
Dendrite counting was performed on the B16-F10 cells. As shown in Figure 7, while FK506 had lower effects on primary dendrite formation, Compound A greatly increased dendricity in these cells. For example, after 24 h of Compound A treatment, 42% of the cell population exhibited more than 4 dendrites compared to 2 dendrites for the majority of DMSO treated cells. The large standard deviation between the experiments may be because the drugs used in the second experiment had undergone several cycles of freeze and thaw. It was observed in the second experiment that it took longer for the drugs to induce morphological changes in B16- F10 cells. It should also be noted that different counting methods were used in the two experiments. In the first experiment, five non-overlapping images were taken of each treatment well and dendrites of 20 cells per image field were counted. In the second experiment, dendrites of 10 cells from 5 non-overlapping fields were counted directly from the microscope due to camera breakdown.
Compound A also induced dendrite formation in the human melanocytes. The majority of neonatal melanocytes maintained in standard culture medium had existing dendritic processes extending from the main cell body. Many of these cells had bipolar or tripolar morphology. Within 72 h treatment with Compound A at 5 μΜ, cells with a far more extensive morphology were observed. In particular, a highly dendritic morphology of Compound A-treated HEMn-DP is evident. See Figure 8(A). Further, Compound A increased mean dendrite numbers, the proportion of cells with more than three dendrites as well as the number of cells with secondary and tertiary (branching) dendrites. Similar changes in dendrite parameters were also observed for HEMn-LP (B-D) and HEMn-DP (E-G). In contrast, 72 h exposure to FK506 had little effect on either primary or secondary dendrite numbers of HEMn-LP. In these experiments, forskolin modestly increased primary dendrite numbers, but did not affect the extent of dendrite branching. EXAMPLE 5
EXPRESSION OF MELANOGENESIS PROTEINS
The expression of tyrosinase, MITF, TRP1 , and TRP2 that are essential in melanogenesis were examined by western blotting. In the B16-F10 mouse melanoma cells, forskolin, FK506, and Compound A increased protein levels of tyrosinase. See, Figure 9(A). Changes in the expressions of the tyrosinase homologous proteins, TRP1 and TRP2, however, were not observed in B16-F10 cells. Surprisingly, there was a decrease in TRP1 expression by Compound A. In addition, MITF protein levels elevated in cells treated by FK506 and Compound A, but not forskolin. See, Figure 9(A). It has been shown that maximum MITF expression was achieved by 8 h of forskolin treatment in B16-F10 cells. The sampling time (24 and 48 h) employed in the current study in might have been too long to detect changes in MITF expression. For human G361 human melanoma cells, Compound A increased the expression of tyrosinase, TRP1 , and TRP2. G361 cells treated with Compound A also showed some elevation in MITF protein levels. See, Figure 9(B). Table 2 summarizes the effects of Compound A on melanogenesis- related parameters in different cells as compared to a DMSO control.
TABLE 2
Figure imgf000059_0001
increase; - = no change
EXAMPLE 6
EFFECT OF COMPOUND A ON MELANOCYTE VIABILITY
The colorimetric MTS assay was used to assess the impact of
Compound A on melanocyte viability in vitro. The result of one experiment,
representative of one of three similar experiments performed, is shown in Figure 10. To assess compound cytotoxicity, cells were cultured for 72 h with different
concentrations of Compound A in triplicate in 96-well microtiter culture plates. At 5 μΜ, a concentration demonstrated to reproducibly stimulate pigmentation-related parameters in cultured melanocytes, Compound A did not affect HEMn-LP viability as determined by this method. At lower concentrations of Compound A (0.5-2.5 μΜ), a modest increase in the cell viability readout was evident. However, an approximate 50% reduction in cell viability occurred when Compound A was added at 10 μΜ. At 20 μΜ, the highest concentration of Compound A tested, cell viability was reduced to about 7% of control values. An approximate 50% reduction in cell viability was produced by forskolin and FK506 concentrations of approximately 45 μΜ. EXAMPLE 7
EFFECTS ON MELANOGENESIS-RELATED PARAMETERS BY RELATED COMPOUNDS
Although the results of melanogenesis-related proteins differed between cell lines, Compound A, in general, induced melanogenesis in both mouse and human melanoma cells. To investigate the potential of other Compound A related compounds in inducing melanogenesis, Compound A (5 μΜ), Compound B (10 μΜ), Compound C (10 μΜ), Compound D (5 μΜ), Compound E (1 μΜ), or Compound F (1 μΜ) were administered to the B16-F10 cells. The doses of the compounds were chosen based on preliminary cytotoxicity experiments on human neonatal skin cells HEMn (see, Example 6). The high cytotoxicity of Compounds D, E and F did not allow higher concentrations of the drugs to be tested. All but Compounds E and F greatly induced dendritogenesis within 24 h of treatment (Figure 1 1 A). Moreover, Compounds A, B, and C showed the greatest effects in promoting tyrosinase activity and melanin production (Figure 1 1 B). A similar trend was also observed for Compounds A, B and C in promoting the expression of tyrosinase and MITF (Figure 1 1 C).
Table 3 summarizes the effects of Compound A and related compounds on melanogenesis-related parameters in B16-F10 cells as compared to a DMSO control.
TABLE 3
Figure imgf000060_0001
increase; - = no change
EXAM PLE 8
To examine quantitatively for impact of the Compound A on therapeutic skin melanization, a patient with solar urticaria receives a single dose (e.g., 0.07 mg to 7 mg for a 70 kg individual) by subcutaneous, subcutaneous implant, or oral administration of Compound A during winter months (November, December, January, February) in the British Columbia, when sun exposure is minimal . Melanin density was assessed spectrophotometrically over a two-month time course, in situ, if the dermis was the therapeutic target.
For cutaneous melanin levels, and their protective ability, solar urticaria, monochromated light testing to geometric dose series (increment ) of wavelengths 300-600 nm are performed at 0, 30 and 60 days, with assessment of weal and flare area and minimum urticarial dose (MUD).
Mean melanin density increase and remain elevated over the course of the study. A significant reduction in weal area occurred across responding
wavelengths from 300 to 600 nm at 60 days after administration.
These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible
embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.
All of the U.S. patents, U.S. patent application publications, U.S. patent application, foreign patents, foreign patent application and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, application and publications to provide yet further embodiments..

Claims

1. A compound of Formula (la):
Figure imgf000062_0001
wherein,
n is 0, 1 , or 2;
Ri is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
R2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
or Ri and R2 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl; R3 is alkyl, alkenyl, aralkyl or aryl;
R4 is alkyl, alkenyl, aralkyl or aryl;
or R3 and R4 together with the nitrogen to which they are both attached, form an optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl; R6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl;
R7 is hydrogen or alkyl; or
R6 and R7 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl, and
each R8 is the same or different and independently alkyl, halo, haloalkyl, aralkyl, heterocyclylalkyl, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7, or -C(0)N(R6)R7.
provided that, the compound of Formula (la) is not:
4-[/V-(3-amino-5-pyrrolidin-1-yl-pyrazol-4-ylidene)-hydrazino]-benzenesulfonamide; 4-{/V 3-amino-5-(4-methylpiperazin-1-yl)-pyrazol-4-ylidene]-hydrazino}- benzenesulfonamide;
3-[/V -(3-amino-5-pyrrolidin-1-yl-pyrazol-4-ylidene)-hydrazino]-/V-methyl- benzenesulfonamide;
3-[/V -(3-amino-5-pyrrolidin-1-yl-pyrazol-4-ylidene)-hydrazino]-benzenesulfonamide 3-[/V -(3-amino-5-dimethylamino-pyrazol-4-ylidene)-hydrazino]-benzenesulfonam 3-[/V -(3-amino-5-dimethylamino-pyrazol-4-ylidene)-hydrazino]-/V-methyl^
benzenesulfonamide;
3-[/V -(3-amino-5-morpholin-4-yl-pyrazol-4-ylidene)-hydrazino]-benzenesulfonam 3-[/V -(3-amino-5-morpholin-4-yl-pyrazol-4-ylidene)-hydrazino]-/V-methyl- benzenesulfonamide; or
3-[/V -(3-amino-5-morpholin-4-yl-pyrazol-4-ylidene)-hydrazino]-/V-(2-hydroxyethy
benzenesulfonamide.
2. The compound of claim 1 , wherein R-i and R2 are both hydrogens.
3. The compound of any of claims 1-2, wherein R3 and R4 are each independently alkyl or aralkyl.
4. The compound of any of claims 1-2, wherein R3 and R4 together with the nitrogen to which they are both attached, form an optionally substituted N- heterocyclyl is optionally substituted piperazinyl, morpholinyl, pyrrolidinyl, or imidazolidinyl.
5. The compound of claim 1 being:
3-[/V-(3-amino-5-methylbenzylaminopyrazol-4-ylidene)-hydrazino]-/\/-methyl- benzenesulfonamide;
3-[/V-(3-amino-5-methylbenzylaminopyrazol-4-ylidene)-hydrazino]-/\/-ethyl- benzenesulfonamide; 3-[/V-(3-amino-5-methylbenzylaminopyraz
benzenesulfonamide; or
3-[/V-(3-amino-5-(4-phenoxycarbonylpiperazin-1 -yl)-pyrazol-4-ylidene)-hydrazino]-/V^ ethyl-benzenesulfonamide .
6. A pharmaceutical composition comprising a pharmaceutical effective amount of a compound of Formula (la), or a pharmaceutically acceptable salt thereof, and a pharmaceutical acceptable excipient.
7. The pharmaceutical composition of claim 6, wherein the pharmaceutical composition is a dermatological composition.
8. A method of stimulating melanogenesis in a mammal in need thereof, the method comprising: administering to the mammal a pharmaceutically effective amount of a compound of Formula I):
Figure imgf000064_0001
(I)
wherein,
m is 0, 1 , 2, or 3;
R-i is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
R2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
or Ri and R2 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl; R3 is alkyl, alkenyl, aralkyl or aryl;
R4 is alkyl, alkenyl, aralkyl or aryl;
or R3 and R4 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl; each R5 is the same or different and independently alkyl, halo, haloalkyi, aralkyi, heterocyclylalkyl, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7,
or -C(0)N(R6)R7;
R6 is hydrogen, alkyl, hydroxyalkyl, aralkyi or aryl;
R7 is hydrogen or alkyl; or
R6 and R7 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl.
9. The method of claim 8 wherein at least one R5 of Formula (I) is an electron-withdrawing group selected from the group consisting of halo, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7, -C(0)N(R6)R7.
10. The method of claim 9 wherein at least one R5 of Formula (I) is -S(0)2-N(R6)R7.
1 1 . The method of any of claims 8-10, wherein R-i and R2 are both hydrogens.
12. The method of any of clams 8-1 1 , wherein R3 and R4 are each independently alkyl or aralkyi.
13. The method of any of claims 8-12 wherein the optionally substituted /V-heterocyclyl is optionally substituted piperazinyl, morpholinyl, pyrrolidinyl, or imidazolidinyl.
14. The method of claim 8 wherein the compound is of Formula (la):
Figure imgf000066_0001
wherein,
n is 0, 1 , or 2;
R-i is hydrogen, alkyl, haloalkyi, alkenyl, aralkyi or aryl;
R2 is hydrogen, alkyl, haloalkyi, alkenyl, aralkyi or aryl;
or Ri and R2 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl; R3 is alkyl, alkenyl, aralkyi or aryl;
R4 is alkyl, alkenyl, aralkyi or aryl;
or R3 and R4 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl; R6 is hydrogen, alkyl, hydroxyalkyl, aralkyi or aryl;
R7 is hydrogen or alkyl; or
R6 and R7 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl, and
each R8 is the same or different and independently alkyl, halo, haloalkyi, aralkyi,
heterocyclylalkyl, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7,
or -C(0)N(R6)R7.
15. The method of claim 14 wherein the compound of Formula (la) is 3-[/V-(3-amino-5-methylbenzylaminopyrazol-4-ylidene)-hydrazino]-/V-methyl- benzenesulfonamide;
3-[/V-(3-amino-5-methylbenzylaminopyrazol-4-ylidene)-hydrazino]-/V-ethyl- benzenesulfonamide; 3-[/V-(3-amino-5-methylbenzylaminopyrazoL
benzenesulfonamide; or
3-[/V-(3-amino-5-(4-phenoxycarbonylpiperazin-1 -yl)-pyrazol-4-ylidene)-hydrazino]-/V^ ethyl-benzenesulfonamide .
16. The method of any of claims 8-15, wherein the mammal has a pigmentation disorder.
17. The method of claim 16, wherein the mammal's pigmentation disorder is vitiligo or leukoderma.
18. The method of claim 16 wherein the mammal's pigmentation disorder is characterized by inadequate or absent melanocytes.
19. The method of any of claims 8-15, wherein stimulating melanogenesis includes tanning.
20. The method of claim 19 wherein the mammal has normal pigmentation and is in need of tanning in the absence of UV exposure.
21 . A method of restoring pigmentation in a mammal having a pigmentation disorder, wherein the method comprises administering to the mammal a therapeutically effective amount of a com ound of Formulae (I):
Figure imgf000067_0001
(I)
wherein,
m is 0, 1 , 2, or 3; Ri is hydrogen, alkyl, haloalkyi, alkenyl, aralkyi or aryl;
R2 is hydrogen, alkyl, haloalkyi, alkenyl, aralkyi or aryl;
or Ri and R2 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl; R3 is alkyl, alkenyl, aralkyi or aryl;
R4 is alkyl, alkenyl, aralkyi or aryl;
or R3 and R4 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl; each R5 is the same or different and independently alkyl, halo, haloalkyi, aralkyi, heterocyclylalkyl, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7, or -C(0)N(R6)R7;
R6 is hydrogen, alkyl, hydroxyalkyl, aralkyi or aryl;
R7 is hydrogen or alkyl; or
R6 and R7 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl.
22. The method of claim 21 wherein at least one R5 of Formula (I) is an electron-withdrawing group selected from the group consisting of halo, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7, -C(0)N(R6)R7.
23. The method of claim 22 wherein at least one R5 of Formula (I) is -S(0)2-N(R6)R7.
24. The method of any of claims 21-23, wherein R-i and R2 are both hydrogens.
25. The method of any of clams 21-24, wherein R3 and R4 are each independently alkyl or aralkyi.
26. The method of any of claims 21-25 wherein the optionally substituted /V-heterocyclyl is optionally substituted piperazinyl, morpholinyl, pyrrolidinyl, or imidazolidinyl.
27. The method of claim 21 wherein the compound is of Formula
(la):
Figure imgf000069_0001
wherein,
n is 0, 1 , or 2;
R-i is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
R2 is hydrogen, alkyl, haloalkyl, alkenyl, aralkyl or aryl;
or Ri and R2 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl; R3 is alkyl, alkenyl, aralkyl or aryl;
R4 is alkyl, alkenyl, aralkyl or aryl;
or R3 and R4 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl; R6 is hydrogen, alkyl, hydroxyalkyl, aralkyl or aryl;
R7 is hydrogen or alkyl; or
R6 and R7 together with the nitrogen to which they are both attached, form an
optionally substituted /V-heterocyclyl or an optionally substituted /V-heteroaryl, and
each R8 is the same or different and independently alkyl, halo, haloalkyl, aralkyl,
heterocyclylalkyl, nitro, cyano, -C(0)R6, -C(0)OR6, -S(0)2-N(R6)R7,
or -C(0)N(R6)R7.
28. The method of claim 27 wherein the compound of Formula (la) is
3-[/V-(3-amino-5-methylbenzylaminopyrazol-4-ylidene)-hydrazino]-/\/-methyl- benzenesulfonamide;
3-[/V-(3-amino-5-methylbenzylaminopyrazol-4-ylidene)-hydrazino]-/\/-ethyl- benzenesulfonamide;
3-[/V-(3-amino-5-methylbenzylaminopyrazol-4-ylidene)-hydrazino]-/\/-(2-hydroxyethyl)- benzenesulfonamide; or
3-[/V-(3-amino-5-(4-phenoxycarbonylpiperazin-1 -yl)-pyrazol-4-ylidene)-hydrazino]-/\/- ethyl-benzenesulfonamide .
29. The method of claim 21 , wherein the mammal's pigmentation disorder is vitiligo or leukoderma.
30. The method of claim 29 wherein the mammal's pigmentation disorder is characterized by inadequate or absent melanocytes.
31 . A method for treating porphyria comprising:
topically administering a therapeutically effective amount of a compound of formula (I) or (la) to a subject in need thereof.
32. A method for treating solar urticaria comprising: topically administering a therapeutically effective amount of a compound of formula (I) or (la) to a subject in need thereof.
33. A method for treating light patches on mammalian skin comprising:
topically administering a therapeutically effective amount of a compound of formula (I) or (la).
34. The method of claim 33 wherein the light patches are results of pigmentation disorders such as leukoderma or vitiligo.
35. A method for restoring hair color by topically administering a therapeutically effective amount of a compound of formula (I) or (la) to the scalp of a subject in need thereof.
36. A method for treating a degenerative neurological disorder by locally or systemically administering a pharmaceutical composition comprising a compound of formula (I) or (la) in an amount effective in stimulating neuromelanin synthesis.
37. The method of claim 36 wherein the degenerative neurological disorder is Parkinson's disease.
38. A method for treating hearing disorder by administering a compound of formula (I) or (la) intra-aurally or systemically, wherein the hearing disorders is characterized by melanocyte insufficiency in the inner ear.
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