US20060079517A1

US20060079517A1 - Reverse-turn mimetics and methods relating thereto

Info

Publication number: US20060079517A1
Application number: US11/292,611
Authority: US
Inventors: Jan Urban; Hiroshi Nakanishi; Min Lee
Original assignee: Myriad Genetics Inc
Current assignee: Myriad Genetics Inc
Priority date: 2001-05-16
Filing date: 2005-12-02
Publication date: 2006-04-13
Also published as: US20030166640A1; AU2002303779A1; WO2002092010A2; US7008941B2; WO2002092010A3

Abstract

Conformationally constrained compounds which mimic the secondary structure of reverse-turn regions of biologically active peptides and proteins having the following structure are disclosed:

wherein A, B, X, R₁, and R₅are as defined herein. Such compounds have utility over a wide range of fields, including use as diagnostic and therapeutic agents. In particular, compounds of this invention are useful in pharmaceutical compositions as anti-inflammatory agents as well as inhibitors of central nervous disorders. Libraries containing the compounds of this invention are also disclosed, as well as methods for screening the same to identify biologically active members.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No. 10/150,481 filed May 16, 2002; which claims the benefit of U.S. Provisional Patent Application No. 60/291,663, filed May 16, 2001, where this provisional application is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates generally to reverse-turn mimetics, including inhibitors of cell adhesion-mediated disease, central nervous system disorders, and several other disorders as well as to a chemical library of reverse-turn mimetics.
2. Description of the Related Art
In the search for new therapeutics, the pharmaceutical industry has increasingly turned to the techniques of combinatorial chemistry, parallel synthesis, and high throughput screening to generate and optimize lead compounds (Combinatorial Chemistry and Molecular Diversity in Drug Discovery Gordon and Kerwin, Eds., John Wiley & Sons, New York, 1998; The Combinatorial Index Bunin, Academic Press, New York, 1998; A Practical Guide to Combinatorial Chemistry Czarnik and DeWitt, Eds., American Chemical Society, Washington, D.C., 1997; High Throughput Screening: The Discovery of Bioactive Substances Devlin, Marcel Dekker, New York, 1997). These techniques can produce libraries of hundreds to hundreds of thousands—or more—of compounds in a short period of time. The libraries are then assayed against targets of interest, often in a highly automated fashion, to identify biologically active compounds. Libraries, which are simply collections of compounds, may be tightly focused around a specific template or contain a variety of unrelated templates. In many instances, the diversity of the library is an important design parameter.
On a basic level, the number of points of diversity on a molecular template or scaffold, i.e., the number of positions at which variation in structure may be introduced, has a practical effect on the ease with which large libraries may be created. When combinatorial techniques are employed, a template that contains three points of diversity would give rise to 8000 compounds if 20 components are used to derivatize each point and a total of 60 reactions are carried out (20³). However, a template with four points of diversity will yield over 50,000 compounds when 15 components are used at each point in a total of 60 reactions (15⁴). In general, large libraries may be created more efficiently on templates allowing more possibilities for derivatization.
In order to increase the chances of finding a biologically active compound for a particular target, it is usually desirable to synthesize a library spanning a range of both conformational space and chemical properties such as hydrophobicity and hydrogen bonding ability. At the same time, low molecular weight is often a goal as well, since compounds of less than 500 Daltons are perceived as more likely to have favorable pharmacokinetic properties in relation to higher molecular weight compounds. All these characteristics point to the continuing need for small compact templates that support a wide range of substituents and which are simple to synthesize.
Reverse-turns comprise one of three classes of protein secondary structure and display three (gamma-turn), four (beta-turns), or more (loops) amino acid side chains in a fixed spatial relationship to each other. Turns have proven important in molecular recognition events (Rose et al., Advances in Protein Chemistry 37:1-109, 1985) and have engendered a burgeoning field of research into small molecule mimetics of them (e.g., Hanessian et al., Tetrahedron 53:12789-12854, 1997). Many mimetics have either been external turn-mimetics which do not allow for the display of all the physiologically relevant side-chains (e.g., Freidinger et al., Science 210:656-8, 1980) or small, conformationally mobile cyclic peptide derivatives (e.g., Viles et al., Eur. J. Biochem. 242:352-62, 1996). However, non-peptide compounds have been developed which closely mimic the secondary structure of reverse-turns found in biologically active proteins or peptides. For example, U.S. Pat. Nos. 5,475,085, 5,670,155 and 5,672,681 to Kahn and published PCT WO94/03494 to Kahn all disclose conformationally constrained, non-peptidic compounds which mimic the three-dimensional structure of reverse-turns. More recently, U.S. Pat. No. 5,929,237 to Kahn, published PCT WO97/15577 to Kahn, published PCT WO98/49168 to Kahn et al., U.S. Pat. No. 6,013,458 to Kahn et al., U.S. Pat. No. 6,184,223 to Kahn et al. and published PCT WO01/16135A2 to Stasiak et al. disclosed additional, highly constrained bicyclic heterocycles as reverse-turn mimetics. Nevertheless, as no one template can mimic every type of turn, there remains a need in the art for additional reverse-turn templates.
Cell adhesion is critical to the viability of living organisms. Adhesion holds multicellular tissues together and directs embryonic development. It plays important roles in wound healing, eradication of infection and blood coagulation. Integrins are a family of cell surface proteins intimately involved in all of these functions. They have been found in nearly every type of human cell except red blood cells. Abnormalities in integrin function contribute to a variety of disorders including inflammatory diseases, heart attack, stroke, and cancer.
Integrins consist of heterodimers of α and β subunits, non-covalently bound to each other. These cell surface receptors extend through the cell membrane into the cytoplasm. At least 15 different α and 9 different β subunits are known. However, because most α proteins associate with only a single β there are about 21 known integrin receptors. On the cell surface the heads of the two subunits contact each other to form a binding surface for extracellular protein ligands, allowing attachment to other cells or to the extracellular matrix. The affinity of these receptors may be regulated by signals from outside or within the cell. For example, recruitment of leukocytes to the site of injury or infection involves a series of adhesive interactions. Weak interaction between endothelial and leukocyte selectins and carbohydrates mediate transient adhesion and rolling of the leukocyte along the vessel wall. Various chemokines and other trigger factors released by the site of inflammation serve as signals to activate integrins from a quiescent to a high affinity state. These activated integrins then bind their cognate ligands on the surface of the endothelial cells, resulting in strong adhesion and flattening of the leukocyte. Subsequently the leukocyte migrates through the endothelium into the tissue below.
Integrin α₄β₁mediates cell adhesion primarily through binding to either vascular cell adhesion molecule-1 (VCAM-1) or an alternatively spliced variant of fibronectin containing the type III connecting segment (IIICS). A variety of cells involved in inflammation express α₄β₁, including lymphocytes, monocytes, basophils and eosinophils, but not neutrophils. Monoclonal antibodies to the α₄subunit have been used to validate α₄-containing integrins as potential therapeutic targets in animal models of rheumatoid arthritis (Barbadillo et al., Springer Semin Immunopathol. 16:427-36, 1995; Issekutz et al., Immunology 88:569-76, 1996), acute colitis (Podolsky et al., J. Clin. Invest. 92:372-80, 1993), multiple sclerosis (Yednock et al., Nature 356:63-6, 1992), asthma (Abraham et al., J. Clin. Invest. 93:776-87, 1994); U.S. Pat. No. 5,871,734) and diabetes (Tsukamoto et al., Cell Immunol. 165:193-201, 1995). More recently, low molecular weight peptidyl derivatives have been produced as competitive inhibitors of α₄β₁and one has been shown to inhibit allergic airway responses in sheep (Lin et al., J. Med. Chem. 42:920-34, 1999).
It has been shown that a key sequence in IIICS involved in binding to α₄β₁is the 25 residue peptide CS1, and within that sequence the minimally recognized motif is the tripeptide, LDV. A similar sequence, IDS, has been implicated in the binding of VCAM-1 to α₄β₁. X-ray crystal structures of an N-terminal two-domain fragment of VCAM-1 show that the IDS sequence is part of an exposed loop linking two beta-strands (Jones et al., Nature 373:539-44, 1995; Wang et al., Proc. Natl. Acad. Sci. USA 92:5714-8, 1995). Cyclic peptides and derivatives thereof which adopt reverse-turn conformations have proven to be inhibitors of VCAM-1 binding to α₄β₁(WO 96/00581; WO 96/06108; Doyle et al., Int. J. Pept. Protein Res. 47:427-36, 1996). In addition, a number of potent and selective (versus α₅β₁) cyclic peptide-based inhibitors have been discovered (Jackson et al., J. Med. Chem. 40:3359-68, 1997). Several non-peptidyl beta-turn mimetics have also been reported to bind α₄β₁with IC₅₀s in the low micromolar range (Souers et al., Bioorg. Med. Chem. Lett. 8:2297-302, 1998). Numerous phenylalanine and tyrosine derivatives have also been disclosed as inhibitors of α₄β₁(WO 99/06390; WO 99/06431; WO 99/06433; WO 99/06434; WO 99/06435; WO 99/06436; WO 99/06437; WO 98/54207; WO 99/10312; WO 99/10313; WO 98/53814; WO 98/53817; WO 98/58902). However, no potent and orally available small molecule inhibitors have been disclosed.
A related integrin, α₄β₇, is expressed on the surface of lymphocytes and binds VCAM-1, fibronectin and mucosal addressin cell adhesion molecule 1 (MAdCAM-1). Integrin α₄β₇and MAdCAM mediate recirculation of a subset of lymphocytes between the blood, gut, and lymphoid tissue. Similar to VCAM-1 and Fibronectin CS-1 there is a tripeptide sequence, LDT, present on the CD loop of MAdCAM-1 which is important for recognition by α₄β₇. An X-ray crystal structure shows this sequence is also part of a turn structure (Tan et al., Structure 6:793-801, 1998). Recent studies have shown that α₄β₇may also play a part in diseases such as asthma (Lobb et al., Ann. NY Acad. Sci. 796:113-23, 1996), inflammatory bowel disease (Fong et al., Immunol. Res. 16:299-311, 1997), and diabetes (Yang et al., Diabetes 46:1542-7, 1997). In addition, while α₄integrins appear to be down-regulated in carcinomas such as cervical and prostate, they appear to be up-regulated in metastatic melanoma (Sanders et al., Cancer Invest. 16:329-44, 1998), suggesting that inhibitors of α₄β₁and α₄β₇may be useful as anticancer agents.
Analgesia has historically been achieved in the central nervous system by opiates and analogs which are addictive, and peripherally by cyclooxygenase inhibitors that have gastric side effects. Substance P antagonists may induce analgesia both centrally and peripherally. In addition, substance P antagonists are inhibitory of neurogenic inflammation.
The neuropeptide receptors for substance P (designated as neurokinin-1) are widely distributed throughout the mammalian nervous system (especially brain and spinal ganglia), the circulatory system and peripheral tissues (especially the duodenum and jejunum) and are involved in regulating a number of diverse biological processes. Such processes include sensory perception of olfaction, vision, audition and pain, movement control, gastric motility, vasodilation, salivation, and micturition (Pernow, Pharmacol. Rev., 35:85-141, 1983). Additionally, the neurokinin-1 and neurokinin-2 receptor subtypes are implicated in synaptic transmission (Laneuville et al., Life Sci. 42:1295-1305, 1988). P The receptor for substance P is a member of the superfamily of G protein-coupled receptors. This superfamily is an extremely diverse group of receptors in terms of activating ligands and biological functions. In addition to the tachykinin receptors, this receptor superfamily includes the opsins, the adrenergic receptors, the muscarinic receptors, the dopamine receptors, the serotonin receptors, a thyroid-stimulating hormone receptor, the product of the oncogene ras, the yeast mating factor receptors, a Dictyostelium cAMP receptor, and receptors for other hormones and neurotransmitters (Hershey et al., J. Biol. Chem. 226:4366-4373, 1991).
Substance P is a naturally occurring undecapeptide belonging to the tachykinin family of peptides, the latter being so-named because of their prompt contractile action on extravascular smooth muscle tissue. The tachykinins are distinguished by a conserved carboxyl-terminal sequence Phe-X-Gly-Leu-Met-NH₂. In addition to substance P the known mammalian tachykinins include neurokinin A and neurokinin B. The current nomenclature designates the receptors for substance P, neurokinin A, and neurokinin B as neurokinin-1, neurokinin-2, and neurokinin-3 respectively. More specifically, substance P is a neuropeptide that is produced in mammals and possesses a characteristic amino acid sequence (Chang et al., Nature New Biol. 232:86, 1971; Veber et al., U.S. Pat. No. 4,680,283). In mammals, substance P acts as a vasodilator, a depressant, stimulates salivation and produces increased capillary permeability. It is also capable of producing both analgesia and hyperalgesia, depending on dose and pain responsiveness of the mammal (Frederickson et al., Science 199:1359, 1978; Oehme et al., Science 208:305, 1980) and plays a role in sensory transmission and pain perception (Jessell et al., Advan. Biochem. Psychopharmacol. 28:189, 1981). For example, substance P is believed to be involved in the neurotransmission of pain sensations (Otsuka et al., “Role of Substance P as a Sensory Transmitter in Spinal Cord and sympathetic Ganglia” in 1982 Substance P in the Nervous System, Ciba Foundation Symposium, 91, 13-34 (published by Pitman); Otsuka et al., Trends Pharmacol. Sci. 8:506-510, 1987), specifically in the transmission of pain in migraine (Sandberg et al., J. Med. Chem. 25:1009, 1982; Moskowitz et al., Trends Pharmacol. Sci. 13:307-311, 1992), and in arthritis (Levin et al., Science 226:547-549, 1984); Lotz et al., Science 235:893-895, 1987). Substance P may also play a role in demyelinating diseases such as multiple sclerosis and amyotrophic lateral sclerosis (Luber-Narod et. al., poster C.I.N.P. XVIIIth Congress, 28^thJun.-2^ndJuly, 1992), and in disorders of bladder function such as bladder detrusor hyperreflexia (Lancet, 16^thMay, 1239, 1992). Tachykinins have also been implicated in gastrointestinal (GI) disorders and diseases of the GI tract, such as inflammatory bowel disease (Mantyh et al., Neuroscience 25:817-37, 1988; Regoli in “Trends in Cluster Headache” Ed. F. Sicuteri et. al., Elsevier Scientific Publisher, Amsterdam, pp. 85-95, 1987) and emesis (Trends Pharmacol. Sci. 9:334-341, 1988; Tatersall et al., Eur. J. Pharmacol. 250, R5-R6, 1993). It is also hypothesized that there is a neurogenic mechanism for arthritis in which substance P may play a role (Kidd et al., Lancet, Nov. 11, 1989; Gronblad et al., J. Rheumatol. 15:1807-1810, 1988). Therefore, substance P is believed to be involved in the inflammatory response in diseases such as rheumatoid arthritis and osteoarthritis (O'Byrne et. al., Arthritis and Rheumatism 33:1023-1028, 1990).
Tachykinin receptor antagonists are believed to be useful for treatment of pain, headache (especially migraine), Alzheimer's disease, multiple sclerosis, attenuation of morphine withdrawal, cardiovascular changes, oedema, such as oedema caused by thermal injury, chronic inflammatory diseases such as rheumatoid arthritis, asthma/bronchial hyperreactivity and other respiratory diseases including allergic rhinitis, inflammatory diseases of the gut including ulcerative colitis and Chrohn's disease, ocular injury and ocular inflammatory diseases, proliferative vitreoretinopathy, irritable bowel syndrome and disorders of bladder function including cystitis and bladder detruser hyperreflexia (Maggi et al., J. Auton. Pharmacol. 13:23-93, 1993; Snider et al., Chem. Ind. 1:792-794, 1991). Other disease areas where tachykinin antagonists are believed to be useful are allergic conditions (Hamelet et al., Can. J. Pharmacol. Physiol. 66:1361-1367, 1988), immunoregulation (Lotz et al., Science 241:1218-1221, 1988; Kimball et al., J. Immunol. 141:3564-3569, 1988; Perianin et. al., Biochem. Biophys. Res. Commun. 161:520, 1989), postoperative pain and nausea (Bountra et al., Eur. J. Pharmacol. 249:R3-R4, 1993; Tattersall et. al., Neuropharmacology 3:259-260, 1994), vasodilation, bronchospasm, reflex or neuronal control of the viscera (Mantyh et. al., Proc. Natl. Acad. Sci. USA 85:3235-3239, 1988) and, possibly by arresting of slowing β-amyloid-mediated neurodegenerative changes (Yankner et al., Science 250:279-282, 1990) in senile dementia of the Alzheimer type, Alzheimer's disease and Downs Syndrome. Tachykinin antagonists may also be useful in the treatment of small cell carcinomas, in particular small cell lung cancer (SCLC) (Langdon et al., Cancer Research 52:4554-4557, 1992). It has further believed that tachykinin receptor antagonists have utility in the following disorders: depression, dysthymic disorders, chronic obstructive airways disease, hypersensitivity disorders such as poison ivy, vasospastic diseases such as angina and Reynauld's disease, fibrosing collagen diseases such as scleroderma and eosinophillic fascioliasis, reflex sympathetic dystrophy such as shoulder/hand syndrome, addiction disorders such as alcoholism, stress related somatic disorders, neuropathy, neuralgia, disorder related to immune enhancement of suppression such as systemic lupus erythmatosus (EPO Pub. No. 0,436,334), ophthalmic diseases such as conjunctivitis, vernal conjunctivitis, and the like, and cutaneous diseases such as contact dennatitis, atopic dermatitis, urticaria, and other eczematoid dermatitis (EPO Pub. No. 0,394,989).
Substance P receptor antagonists may be useful in mediating neurogenic mucus secretion in mammalian airways and hence provide treatment and symptomatic relief in diseases characterized by mucus secretion, in particular, cystic fibrosis (Ramnarine et al., abstract presented at 1993 ALA/ATS Int'l Conference, 16-19 May 1993, published in Am. Rev. of Respiratory Dis., May 1993). Neurokinin-1 receptor antagonists alone or in combination with bradykinin receptor antagonists may also be useful in the prevention and treatment of inflammatory conditions in the lower urinary tract, especially cystitis (Giuliani et al., J. Urology 150:1014-1017, 1993). Furthermore, antagonists selective for the neurokinin-1 and/or neurokinin-2 receptor may be useful in the treatment of asthmatic disease (Frossard et. al., Life Sci. 49:1941-1953, 1991; Advenier et al., Biochem. Biophys. Res. Comm. 184:1418-1424, 1992; Barnes et al., Trends Pharmacol. Sci. 11:185-189, 1993).
The following documents relate to compounds that exhibit activity as neurokinin antagonists: U.S. Pat. No. 6,194,406 B1; U.S. Pat. No. 6,191,135 B1; U.S. Pat. No. 6,177,450 B1; U.S. Pat. No. 6,147,083; U.S. Pat. No. 6,110,919; U.S. Pat. No. 6,063,926; U.S. Pat. No. 6,048,859.
While significant advances have been made in the synthesis and identification of conformationally constrained, reverse-turn mimetics, there is still a need in the art for small molecules that mimic the secondary structure of peptides. There is also a need in the art for libraries containing such members, particularly those small templates capable of supporting a high diversity of substituents. In addition, there is a need in the art for techniques for synthesizing these libraries and screening the library members against biological targets to identify bioactive library members. Further, there is a need in the art for small, orally available inhibitors of integrins, for use in treating inflammatory diseases and cardiovascular diseases, as well as some cancers. In particular there is a need for inhibitors of α₄β₁and α₄β₇, for use in the treatment of rheumatoid arthritis, asthma, diabetes and inflammatory bowel disease. Further, there is a need in the art for small, orally available inhibitors of neurokinins, for use in treating inflammatory diseases, central nervous system disorders, as well as several other disorders. In particular there is a need for inhibitors of neurokinin-1, neurokinin-2, and neurokinin-3, for use in the treatment or prevention of various mammalian disease states, for example asthma, cough, chronic obstructive pulmonary disease (COPD), bronchospasm, emesis, neurodegenerative disease, ocular disease, inflammatory diseases such as arthritis, central nervous system conditions such as migraine and epilepsy, nociception, psychosis, and various gastrointestinal disorders such as Crohn's disease.
The present invention fulfills these needs and provides further related advantages.

SUMMARY OF THE INVENTION

In brief, the present invention is directed to conformationally constrained compounds which mimic the secondary structure of reverse-turn regions of biologically active peptides and proteins (also referred to herein as “reverse-turn mimetics”). The compounds of the present invention have the following general structure (I):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein A, B, X and R₁and R₅are as defined below.
The present invention is also directed to libraries containing compounds of structure (I), as well as methods for synthesizing such libraries and methods for screening the same to identify biologically active compounds. In addition, compositions containing a compound of this invention in combination with a pharmaceutically acceptable carrier are disclosed. Methods of use for treating cell-adhesion-mediated disease with the compounds of this invention and compositions comprising them are also disclosed. Further, methods of use for treatment and prevention of inflammatory and central nervous system disorders, as well as several other disorders with the compounds of this invention and compositions comprising them are also disclosed.
These and other aspects of this invention will be apparent upon reference to the following detailed description. To this end, various references are set forth herein which describe in more detail certain procedures, compounds and/or compositions, and are incorporated by reference in their entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-4 illustrate representative reaction schemes for the synthesis of reverse-turn mimetics of this invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to reverse-turn mimetics and chemical libraries containing reverse-turn mimetics. The reverse-turn mimetics of the present invention are useful as bioactive agents, including (but not limited to) use as diagnostic, prophylactic and/or therapeutic agents, especially as anti-inflammatory agents, for central nervous system disorders, and as well as several other disorders. The reverse-turn mimetic libraries of this invention are useful in the identification of such bioactive agents. In the practice of the present invention, the libraries may contain from tens to hundreds to thousands (or greater) of individual reverse-turn mimetics (also referred to herein as “members”).
In one aspect of the present invention, a reverse-turn mimetic is disclosed having the following structure (I):

and pharmaceutically acceptable salts and stereoisomers thereof,
wherein
A is —(CR₂R_2a)_m— where m is 1, 2 or 3;
B is —(CR₃R_3a)_n— where n is 1, 2, 3, or 4;
X is —N(R₄)—, —O—, or —S—;
R₂and R₃are, at each occurrence, the same or different and independently an amino acid side chain moiety or amino acid side chain derivative, a peptide or peptide derivative, a linker or a solid support;
R₅is an amino acid side chain moiety or amino acid side chain derivative;
R_2aand R_3aare, at each occurrence, the same or different and independently hydrogen, hydroxy, —COOH, —CONH₂, —R₆, —OR₆, —COOR₆, —COn₆or —CONHR₆, where R₆is lower alkyl optionally substituted with halogen or hydroxy;
R₁and R₄are the same or different and represent the remainder of the molecule; and
wherein R₁and R₂taken together optionally form a fused heterocycle or substituted heterocycle.

As used herein, an “amino acid side chain moiety” represents any amino acid side chain moiety present in naturally occurring proteins including (but not limited to) the naturally occurring amino acid side chain moieties identified in Table 1 below. Other naturally occurring amino acid side chain moieties of this invention include (but are not limited to) the side chain moieties of 3,5-dibromotyrosine, 3,5-diiodotyrosine, hydroxylysine, γ-carboxyglutamate, phosphotyrosine, phosphothreonine and phosphoserine. In addition, glycosylated amino acid side chains may also be used in the practice of this invention, including (but not limited to) glycosylated threonine, serine, glutamine and asparagine.

TABLE 1


AMINO ACID SIDE CHAIN MOIETIES

	Amino Acid Side Chain Moiety	Amino Acid


	—H	Glycine
	—CH₃	Alanine
	—CH(CH₃)₂	Valine
	—CH₂CH(CH₃)₂	Leucine
	—CH(CH₃)CH₂CH₃	Isoleucine
	—(CH₂)₄NH₂	Lysine
	—(CH₂)₃NHC(NH₂)NH₂	Arginine

		Histidine

	—CH₂COOH	Aspartic acid
	—CH₂CH₂COOH	Glutamic acid
	—CH₂CONH₂	Asparagine
	—CH₂CH₂CONH₂	Glutamine

		Phenylalanine

		Tyrosine

		Tryptophan

	—CH₂SH	Cysteine
	—CH₂CH₂SCH₃	Methionine
	—CH₂OH	Serine
	—CH(OH)CH₃	Threonine

		Proline

		Hydroxyproline

In addition, as used herein, an “amino acid side chain derivative” represents modifications and/or variations to naturally occurring amino acid side chain moieties. For example, the amino acid side chain moieties of alanine, valine, leucine, isoleucine and phenylalanine may generally be classified as alkyl, aryl, or arylalkyl moieties, optionally substituted with one or more substituents as defined below. Accordingly, representative amino acid side chain derivatives include substituted or unsubstituted alkyl, aryl and arylalkyl moieties. Similarly, the amino acid side chain moieties of histidine, tryptophan, proline and hydroxyproline may generally be classified as heterocyclic or heterocyclicalkyl moieties, optionally substituted with one or more substituents as defined below. Accordingly, representative amino acid side chain derivatives also include substituted or unsubstituted heterocycle and heterocyclealkyl moieties.
“Alkyl” means a straight chain or branched, cyclic or noncyclic, saturated or unsaturated alkyl containing from 1 to 12 carbon atoms (also referred to herein as “C_1-12alkyl”). Similarly, a “lower alkyl” is as defined above, but contains from 1 to 4 carbon atoms (also referred to herein as a “C_1-4alkyl”). Representative saturated straight chain alkyls include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, and the like; while saturated branched alkyls include isopropyl, sec-butyl, isobutyl, tert-butyl, isopentyl, and the like. Representative saturated cyclic alkyls include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like. Unsaturated alkyls contain at least one double or triple bond between adjacent carbon atoms (referred to as an “alkenyl” or “alkynyl”, respectively). Representative straight chain and branched alkenyls include ethylenyl, propylenyl, 1-butenyl, 2-butenyl, isobutenyl, l-pentenyl, 2-pentenyl, 3-methyl-1-butenyl, 2-methyl-2-butenyl, 2,3-dimethyl-2-butenyl, and the like; while representative straight chain and branched alkynyls include acetylenyl, propynyl, 1-butynyl, 2-butynyl, 1-pentynyl, 2-pentynyl, 3-methyl-1 butynyl, and the like. Representative unsaturated cyclic alkyls include cyclopentenyl and cyclohexenyl, and the like.
“Aryl” means an aromatic carbocyclic moiety containing from 6 to 12 carbon atoms (also referred to herein as a “C_6-12aryl”), such as phenyl and naphthyl.
“Arylalkyl” means an alkyl having at least one alkyl hydrogen atom replaced with an aryl moiety, such as benzyl, —(CH₂)₂(aryl), —(CH₂)₃(aryl), —CH(aryl)₂, and the like.
“Heteroaryl” means an aromatic heterocycle ring of 5- to 10 members and having at least one heteroatom selected from nitrogen, oxygen and sulfur, and containing at least 1 carbon atom, including both mono- and bicyclic ring systems. Representative heteroaryls are pyridyl, furyl, benzofuranyl, thiophenyl, benzothiophenyl, quinolinyl, pyrrolyl, indolyl, oxazolyl, benzoxazolyl, imidazolyl, benzimidazolyl, thiazolyl, benzothiazolyl, isoxazolyl, pyrazolyl, isothiazolyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, cinnolinyl, phthalazinyl, and quinazolinyl.
“Heteroarylalkyl” means an alkyl having at least one alkyl hydrogen atom replaced with a heteroaryl moiety, such as —CH₂(heteroaryl) and the like.
“Heterocycle” means a 5- to 7-membered monocyclic, or 7- to 10-membered bicyclic, heterocyclic ring which is either saturated, unsaturated, or aromatic, and which contains from 1 to 4 heteroatoms independently selected from nitrogen, oxygen and sulfur, and wherein the nitrogen and sulfur heteroatoms may be optionally oxidized, and the nitrogen heteroatom may be optionally quaternized, including bicyclic rings in which any of the above heterocycles are fused to a benzene ring. The heterocycle may be attached via any heteroatom or carbon atom. Heterocycles include heteroaryls as defined below. Thus, in addition to the heteroaryls listed below, heterocycles also include morpholinyl, pyrrolidinonyl, pyrrolidinyl, piperidinyl, hydantoinyl, valerolactamyl, oxiranyl, oxetanyl, aziridinyl, azetidinyl, tetrahydrofuranyl, tetrahydropyranyl, tetrahydropyridinyl, tetrahydroprimidinyl, tetrahydrothiophenyl, tetrahydrothiopyranyl, tetrahydropyrimidinyl, tetrahydrothiophenyl, tetrahydrothiopyranyl, and the like.
“Heterocyclealkyl” means an alkyl having at least one alkyl hydrogen atom replaced with a heterocycle moiety, such as —CH₂(heterocycle), —(CH₂)₂(heterocycle), and the like.
The term “substituted” as used herein means any of the above groups—that is, alkyl, aryl, arylalkyl, heterocycle, heterocyclealkyl, heteroaryl or heteroarylalkyl—wherein at least one hydrogen atom is replaced with a substituent. In the case of a oxo substituent (“═O”) two hydrogen atoms are replaced. A “substituent” in this regard is halogen, oxo, hydroxy, haloalkyl, —R, —OR, —C(═O)R, —C(═O)OR, —C(═O)NRR, —NRR, —NRC(═O)R, —NRC(═O)OR, —NRC(═O)NRR, —OC(═O)R, —OC(═O)OR, —OC(═O)NRR, —SH, —SR, —SOR, —SO₂R, —NRSO₂R, —Si(R)₃, or —OP(OR)₃, wherein each occurrence of R is the same or different and independently an amino acid side chain moiety or an amino acid side chain derivative generally, or more specifically hydrogen, alkyl, aryl, arylalkyl, heterocycle or heterocyclealkyl, or wherein any two R groups attached to the same nitrogen atom, taken together with the nitrogen atom to which they are attached, form a heterocyclic ring or a substituted heterocyclic ring.
A “peptide” means at least two naturally or unnaturally occurring alpha-amino acids joined via a peptide bond. Depending upon the number of amino acids joined via peptide bonds, the resulting peptide may also be referred to as a “polypeptide” or “protein.” Similarly, a “peptide derivative” means a peptide which has been covalently modified and/or which contains amino acids other than alpha-amino acids. Representative peptide derivatives include peptides which are N-alkylated, N-acylated or N-sulfonylated at the amino termini, with, for example, methyl, benzyl, acetyl, benzoyl, methanesulfonyl, phenylsulfonyl, allyloxycarbonyl, t-butyloxycarbonyl, benzyloxycarbonyl, or fluorenyloxycarbonyl moieties; peptides in which the carboxy termini are esterified (methyl, ethyl, benzyl) or reduced to a hydroxy or aldehyde; peptides which are N-alkylated at peptide bonds with, for example, methyl or 2-hydroxy-4-methoxybenzyl; and peptides which incorporate beta- or gamma-amino acids such as beta-alanine or gamma-aminobutyric acid.
A “linker” is any covalent bridging moiety that facilitates linkage of a compound of structure (I), through the respective R₁, R₂, R_2a, R₃, R_3a, R₄and/or R₅moiety, to another moiety, agent, compound, solid support, molecule, amino acid, peptide or protein. For example, the compounds of this invention may be linked to one or more known compounds, such as biotin, for use in diagnostic or screening assays. Furthermore, one (or more) of R₁, R₂, R_2a, R₃, R_3a, R₄or R₅may be a linker joining the compound of structure (I) to a solid support (such as a support used in solid phase peptide synthesis). Examples of such linkers include p-alkoxybenzyl alcohol, phenylacetamidomethyl, and 2-chlorotrityl chloride. In this context, linkage to another moiety or compound, or to a solid support, is preferable at the R₁or R₄position.
A “solid support” means any composition of matter to which another compound is attached directly or attached through a linker and which is insoluble in at least one solvent that the attached compound is soluble in. Alternatively, a “solid support” may be a composition of matter with similar solubility characteristics to the attached compound, but which may be readily precipitated from solution and filtered off as a solid. Representative examples include polystyrene, polyethylene glycol, polystyrene grafted with polyethylene glycol, polyacrylamide, polyamide-polyethylene glycol copolymer, controlled-pore glass, and silica.
The phrase “remainder of the molecule” means any moiety, agent, compound, solid support, molecule, linker, amino acid, peptide or protein covalently attached to the reverse-turn mimetic at either the R₁and/or R₄positions, including amino acid side chain moieties, amino acid side chain derivatives and peptide derivatives as defined above. Accordingly, an alternative depiction of structure (I), the bond between the ring nitrogen atoms and the corresponding R₁and R₄moieties may be left undefined, as represented by the following structure (I′) when X is —N(R₄)— and structure (I″) when X is O or S:

wherein “______” represents the remainder of the molecule joined to the corresponding ring nitrogen through a covalent bond, and A, B and R₅and are as defined above.
In an embodiment of structure (I), X is —N(R₄)—, R₅is hydrogen, and the compounds of this invention have the following structure (II):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein A, B, R₁and R₄are as defined above.
In a more specific embodiment of structure (II), n is 1, R_3ais hydrogen, B is —CH(R₃)—, and the compounds of this invention have the following structure (III):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein A, R₁, R₃and R₄are as defined above.
In a still more specific embodiment of structure (II), n is 2, all occurrences of R_3aare hydrogen, B is —CH(R₃)CH(R₃)—, and the compounds of this invention have the following structure (IV):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein A, R₁, R₃, R₃and R₄are as defined above.
In a more specific embodiment of structure (II), m is 1, R_2ais hydrogen, A is —CH(R₂)—, and the compounds of this invention have the following structure (V):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein B, R₁, R₂and R₄are as defined above.
In a still more specific embodiment of structure (V), n is 1, R_3ais hydrogen, B is —CH(R₃)—, and the compounds of this invention have the following structure (VI):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein R₁, R₂, R₃and R₄are as defined above.
In a still more specific embodiment of structure (V), n is 2, all occurrences of R_3aare hydrogen, B is —C(R_3a)(R₃)C(R_3a)(R₃)—, and the compounds of this invention have the following structure (VII):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein R₁, R₂, R₃, R₃and R₄are as defined above.
In a still more specific embodiment of structure (II), m is 1, 2, or 3, all occurrences of R₂and R_2aare hydrogen, and the compounds of this invention have the following structure (VIII):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein m, B, R₁and R₄are as defined above.
In a still more specific embodiment of structure (II), n is 1, 2, 3, or 4, all occurrences of R₃and R_3aare hydrogen, and the compounds of this invention have the following structure (IX):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein n, A, R₁and R₄are as defined above.
In an embodiment of structure (I), X is —O—, R₅is hydrogen, and the compounds of this invention have the following structure (X):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein A, B and R₁are as defined above.
In an embodiment of structure (I), X is —S—, R₅is hydrogen, and the compounds of this invention have the following structure (XI):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein A, B and R₁are as defined above.
In a more specific embodiment of structure (X), n is 1, R_3ais hydrogen, B is —CH(R₃)—, and the compounds of this invention have the following structure (XII):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein A, R₁and R₃are as defined above.
In a still more specific embodiment of structure (X), n is 2, all occurrences of R_3aare hydrogen, B is —CH(R₃)CH(R₃)—, and the compounds of this invention have the following structure (XIII):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein A, R₁, R₃and R₃are as defined above.
In a more specific embodiment of structure (X), m is 1, R_2ais hydrogen, A is —CH(R₂)—, and the compounds of this invention have the following structure (XIV):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein B, R₁, and R₂are as defined above.
In a still more specific embodiment of structure (XIV), n is 1, R_3ais hydrogen and the compounds of this invention have the following structure (XV):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein R₁, R₂and R₃are as defined above.
In a still more specific embodiment of structure (XIV), n is 2, all occurrences of R_3aare hydrogen, B is —C(R_3a)(R₃)C(R_3a)(R₃)—, and the compounds of this invention have the following structure (XVI):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein R₁, R₂, R₃and R₃are as defined above.
In a still more specific embodiment of structure (X), m is 1, 2, or 3, all occurrences of R₂and R_2aare hydrogen, and the compounds of this invention have the following structure (XVII):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein m, B and R₁are as defined above.
In a still more specific embodiment of structure (X), n is 1, 2, 3, or 4, all occurrences of R₃and R_3aare hydrogen, and the compounds of this invention have the following structure (XVIII):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein n, A and R₁are as defined above.
In a still more specific embodiment of structure (I), R₁taken together with R₂forms a fused heterocycle or substituted heterocycle and the compounds of this invention have the following structure (XIX):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein B, X, R_2aand R₅are as defined above, and R′ is one or more optional heterocycle substituents as defined previously.
In yet a still more specific embodiment of structure (XIX), the compounds of this invention have the following structure (XX):

including pharmaceutically acceptable salts and stereoisomers thereof, wherein l is 0, 1 or 2; B, X, R_2aand R₅are as defined above; and R′ is one or more optional substituents selected from —OR and —OC(O)R, where R is an amino acid side chain moiety or an amino acid side chain derivative.
In one embodiment of structure (I), each occurrence of R_2aand R_3aare hydrogen, R₅is hydrogen or independently an amino acid side chain moiety or amino acid side chain derivative, R₁, R₄and each occurrence of R₂and R₃are the same or different and independently an amino acid side chain moiety or amino acid side chain derivative. In a further embodiment of structure (I), R₁is —C(═O)OR, —C(═O)NHR or —SO₂R, where R is an amino acid side chain moiety or an amino acid side chain derivative, and in another embodiment R is aryl or arylalkyl optionally substituted with halogen, —OH, —COOH, —NH₂or C_1-4alkyl.
In structure (I) above, a solid line designation for attachment of the various R groups to a carbon atom on the fused bicyclic ring indicates that these R groups may lie either above or below the plane of the page. If a reverse-turn mimetic of this invention is intended to mimic a reverse-turn of naturally occurring amino acids (i.e., “L-amino acids”), the R groups would generally lie below the plane of the page (i.e., “
R”) in structure (I). However, if the reverse-turn mimetic of this invention is intended to mimic a reverse-turn containing one or more D-amino acids, then the corresponding R group or groups would lie above the plane of the page (i.e., “
R”) in structure (I).
The reverse-turn mimetics of the present invention may generally be prepared by sequential coupling of the individual component pieces either stepwise in solution or by solid phase synthesis as commonly practiced in solid phase peptide synthesis.
The reverse-turn mimetic of structure (I) may be made according to the reaction scheme set forth in FIGS. 1-4 and methods as presented in Example 2. More specifically, the reverse-turn mimetics of structure (II) may be made by the reaction schemes set forth in FIGS. 1 and 2. The reverse-turn mimetics of structure (X) may be made by the reaction schemes set forth in FIGS. 3 and 4. The reverse-turn mimetics of structure (XI) may also be made by the reaction schemes set forth in FIGS. 3 and 4, but replacing oxygen at the X position with sulfur.
In this invention, libraries containing reverse-turn mimetics of the present invention are disclosed. Once assembled, the libraries of the present invention may be screened to identify individual members having bioactivity. Such screening of the libraries for bioactive members may involve, for example, evaluating the binding activity of the members of the library or evaluating the effect the library members have on a functional assay. Screening is normally accomplished by contacting the library members (or a subset of library members) with a target of interest, such as, for example, an antibody, enzyme, receptor or cell line. Library members which are capable of interacting with the target of interest are referred to herein as “bioactive library members” or “bioactive mimetics”. For example, a bioactive mimetic may be a library member which is capable of binding to an antibody or receptor, which is capable of inhibiting an enzyme, or which is capable of eliciting or antagonizing a functional response associated, for example, with a cell line. In other words, the screening of the libraries of the present invention determines which library members are capable of interacting with one or more biological targets of interest. Furthermore, when interaction does occur, the bioactive mimetic (or mimetics) may then be identified from the library members. The identification of a single (or limited number) of bioactive mimetic(s) from the library yields reverse-turn mimetics which are themselves biologically active, and thus useful as diagnostic, prophylactic or therapeutic agents, and may further be used to significantly advance identification of lead compounds in these fields.
Synthesis of the peptide mimetics of the library of the present invention may be accomplished using known peptide synthesis techniques, in combination with the component pieces of this invention. More specifically, any amino acid sequence may be added as any of the R₁, R₂, R_2a, R₃, R_3a, R₄or R₅moieties of the conformationally constrained reverse-turn mimetic. Preferably the amino acid sequence may be added as the R₁or R₄moieties. To this end, the mimetics may be synthesized on a solid support (such as polystyrene utilizing 4-hydroxymethylphenoxybutyrate as a linker) by known techniques (see, e.g., John M. Stewart and Janis D. Young, Solid Phase Peptide Synthesis, 1984, Pierce Chemical Comp., Rockford, Ill.; Atherton, E., Shepard, R. C. Solid Phase Peptide Synthesis: A Practical Approach; IRL: Oxford, 1989) or on a silyl-linked resin by alcohol attachment (Randolph et al., J. Am. Chem. Soc. 117:5712-14, 1995). The utility and ease of synthesis of the present invention is further exemplified by the applicability of wide variety of commercially available resins. To this end, a core of either polystyrene or ArgoGel (polyethyleneglycol grafted polystyrene; Argonaut, San Carlos, Calif.) utilizing aminomethyl polystyrene, benzhydrylamine (BHA), methylbenzhydrylamine (MBHA) (Matsueda et al., Peptides 2:45, 1981), phenoxybenzylalcohol (Wang resin) (Wang J. Am. Chem. Soc. 95:1328, 1973), 2-clorotrytyl (Barlos et al., Tetrahedron Lett. 30:3943, 1989, ibid 30:3947, 1989), and PAL (Albericio et al., J. Org. Chem. 55:3730 1990) resins and other resins could be used in the synthesis of the present invention.
In addition, a combination of both solution and solid phase synthesis techniques may be utilized to synthesize the peptide mimetics of this invention. For example, a solid support may be utilized to synthesize the linear peptide sequence up to the point that the conformationally constrained reverse-turn is added to the sequence. A suitable conformationally constrained reverse-turn mimetic which has been previously synthesized by solution synthesis techniques may then be added as the next “amino acid” to the solid phase synthesis (i.e., the conformationally constrained reverse-turn mimetic, which has at least two reactive sites, may be utilized as the next residue to be added to the linear peptide). Upon incorporation of the conformationally constrained reverse-turn mimetic into the sequence, additional amino acids may then be added to complete the peptide bound to the solid support. Alternatively, the linear N-terminus and C-terminus protected peptide sequences may be synthesized on a solid support, removed from the support, and then coupled to the conformationally constrained reverse-turn mimetic in solution using known solution coupling techniques.
In another aspect of this invention, methods for constructing the libraries are disclosed. Traditional combinatorial chemistry (e.g., The Combinatorial Index Bunin, Academic Press, New York, 1998; Gallop et al., J. Med. Chem. 37:1233-1251, 1994) and parallel synthesis techniques permit a vast number of compounds to be rapidly prepared by the sequential combination of reagents to a basic molecular scaffold. For example, the above disclosed synthesis may be carried out using the directed sorting technique of Nicolaou and coworkers. (Nicolaou et al., Angew. Chem. Int'l Ed. 34:2289-2291, 1995). Presently, equipment for this technique is commercially available from IRORI (La Jolla, Calif.). Alternatively, the above disclosed synthesis may be carried out by parallel synthesis using a 48- or 96-well plate format wherein each well contains a fritted outlet for draining solvents and reagents (A Practical Guide to Combinatorial Chemistry Czarnik and DeWitt, Eds., American Chemical Society, Washington, D.C., 1997). Robbins (Sunnyvale, Calif.), Charybdis (Carlsbad, Calif.) and Bohdan (Chicago, Ill.) presently offer suitable equipment for this technique.
In a further aspect of this invention, methods for screening the libraries for bioactivity and isolating bioactive library members are disclosed. The libraries of the present invention may be screened for bioactivity by a variety of techniques and methods. Generally, the screening assay may be performed by (1) contacting a library with a biological target of interest, such as a receptor, and allowing binding to occur between the mimetics of the library and the target, and (2) detecting the binding event by an appropriate assay, such as by the colorimetric assay disclosed by Lam et al. (Nature 354:82-84, 1991) or Griminski et al. (Biotechnology 12:1008-1011, 1994). In a preferred embodiment, the library members are in solution and the target is immobilized on a solid phase. Alternatively, the library may be immobilized on a solid phase and may be probed by contacting it with the target in solution.
In another aspect, the present invention encompasses pharmaceutical compositions prepared for storage or administration which comprise a therapeutically effective amount of a compound of the present invention in a pharmaceutically acceptable carrier or diluent. Therapy with inhibitors of cell adhesion is indicated for the treatment and prevention of a variety of inflammatory conditions, particularly rheumatoid arthritis, inflammatory bowel disease and asthma. Those experienced in this field are readily aware of the circumstances requiring anti-inflammatory therapy.
The “therapeutically effective amount” of a compound of the present invention will depend on the route of administration, the type of warm-blooded mammal being treated, and the physical characteristics of the specific mammal under consideration. These factors and their relationship to determining this amount are well known to skilled practitioners in the medical arts. This amount and the method of administration can be tailored to achieve optimal efficacy but will depend on such factors as weight, diet, concurrent medication and other factors which as noted those skilled in the medical arts will recognize.
The “therapeutically effective amount” of the compound of the present invention can range broadly depending upon the desired affects and the therapeutic indication. Typically, dosages will be between about 0.01 mg/kg and 100 mg/kg body weight, preferably between about 0.01 and 10 mg/kg, body weight.
“Pharmaceutically acceptable carriers” for therapeutic use, including diluents, are well known in the pharmaceutical art, and are described, for example, in Remingtons Pharmaceutical Sciences, Mack Publishing Co. (Gennaro Ed. 1985). For example, sterile saline and phosphate-buffered saline at physiological pH may be used. Preservatives, stabilizers, dyes and even flavoring agents may be provided in the pharmaceutical composition. For example, sodium benzoate, sorbic acid and esters of p-hydroxybenzoic acid may be added as preservatives. In addition, antioxidants and suspending agents may be used.
Compounds of the present invention are useful for prevention and treatment of any condition in which an excess of integrin-mediated cell adhesion is a contributing factor. In particular, the compounds of the present invention are useful as agents for the prevention and treatment of inflammation. In the practice of the methods of this invention, a composition containing a therapeutically effective amount of a compound of this invention is administered to a warm-blooded mammal in need thereof. For example, the compounds of this invention may be administered to a warm-blooded mammal that has been diagnosed with, or is at risk of developing a condition selected from rheumatoid arthritis, atherosclerosis, Alzheimer's disease, AIDS dementia, ARDS, asthma, allergies, inflammatory bowel disease, CNS inflammation, atopic dermatitis, type I diabetes, encephalitis, myocardial ischemia, multiple sclerosis, meningitis, nephritis, reperfusion injury, restenosis, retinitis, psoriasis, stroke and tumor metastasis.
Multiple sclerosis (MS) is a progressively debilitating autoimmune disease of the central nervous system. Presently the exact antigen triggering the immune response is unknown. However, macrophages appear to attack and initiate the destruction of the fatty myelin sheaths surrounding nerve fibers in the brain. In an animal model of MS (experimental allergic encephalomyelitis) murine monoclonal antibodies to α₄β₁blocked adhesion of the leukocytes to the endothelium, and prevented inflammation of the central nervous system and subsequent paralysis of the animals (Yednock, Cannon et al., Nature 356: 63-6, 1992).
The compounds of the present invention are useful in the prevention and treatment of a wide variety of clinical conditions which are characterized by the presence of an excess tachykinin, in particular substance P, activity. These conditions may include disorders of the central nervous system such as anxiety, depression, psychosis and schizophrenia; epilepsy; neurodegenerative disorders such as dementia, including senile dementia of the Alzheimer type, Alzheimer's disease and Down's syndrome; demyelinating diseases such as multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS; Lou Gehrig's disease) and other neuropathological disorders such as peripheral neuropathy, or example AIDS related neuropathy, diabetic neuropathy, chemotherapy-induced neuropathy, and other neuralgias; small cell carcinomas such as small cell lung cancer; respiratory diseases, particularly those associated with excess mucus secretion, such as chronic obstructive airways disease, bronchopneumonia, chronic bronchitis, acute bronchitis, diffuse panbronchilitis, emphysema, cystic fibrosis, asthma, and bronchospasm; airways disease modulated by neurogenic inflammation; laryngopharhngitis; bronchiectasis; conoisis; whooping cough; pulmonary tuberculosis; diseases associated with decreased glandular secretions, including lacrimation, such as Sjogren's syndrome, hyperlipoproteinemias IV and V, hemochromatosis, sarcoidosis, or amyloidosis; iritis; inflammatory diseases such as inflammatory bowel disease, inflammatory intestinal disease, psoriasis, fibrositis, ocular inflammation, osteoarthritis, rheumatoid arthritis, pruritis, and sunburn; hepatitis; allergies such eczema and rhinitis; hyper sensitivity disorders such as poison ivy; ophthalmic diseases such a conjunctivitis, vernal conjunctivitis, dry eye syndrome, and the like; ophthalmic conditions associated with cell proliferation such as proliferative vitreoretinopathy; cutaneous diseases such as contact dermatitis, atopic dermatitis, urticaria, and other eczematoid dermatitis; hemodialysis-associated itching; lichen planus; oedema, such as oedema caused by thermal injury; addiction disorders such as alcoholism; mental disease, particularly anxiety and depression; stress related somatic disorders; reflex sympathetic dystrophy such as shoulder/hand syndrome; dysthymic disorders; tenalgia attended to hyperlipidemia; postoperative neuroma, particularly of mastectomy; vulvar vestibulitis; amniogenesis; adverse immunological reactions such as rejection of transplanted tissues and disorders related to immune enhancement of suppression, such as systemic lupus erythmatosus; gastrointestinal (GI) disorders, including inflammatory disorders, and disease of the GI tract, such as gastritis, gastroduodenal ulcers, gastric carcinomas, gastric lymphomas, disorders associated with the neuronal control of viscera such as ulcerative colitis, Crohn's disease, irritable bowel syndrome, nausea, and emesis, including acute, delayed, post-operative, late-phase, and anticipatory emesis, such as emesis or nausea induced by for example chemotherapy, radiation, surgery, migraine, toxins, such as metabolic or microbial toxins, viral or bacterial infections, pregnancy, vestibular disorder, motion, mechanical stimulation, gastrointestinal obstruction, reduced gastrointestinal motility, visceral pain, psychological stress or disturbance, high altitude, weightlessness opioid analgesics, intoxication, resulting for example from consumption of alcohol, and variations in intercranial pressure, in particular, for example, drug or radiation induced emesis or post-operative nausea and vomiting; disorders of bladder function such as cystitis, bladder detrusor hyperreflexia, and incontinence; fibrosing and collagen diseases such as scleroderma and eosinophilic fascioliasis; disorders of blood flow caused by vasodilation and vasospastic diseases such as angina, migraine and Reynaud's disease; and pain of nociception, for example, chronic pain of that attributable to or associated with any of the foregoing conditions especially the transmission of pain in migraine, of such as headache, toothache, cancerous pain, back pain, and superficial pain on congelation, burn, herpes zoster of diabetic neuropathy. Hence, these compounds may be readily adapted to therapeutic use for the treatment of physiological disorders associated with an excessive stimulation of tachykinin receptors, especially neurokinin-1 and as neurokinin-1 antagonists in the control and/or treatment of any of the aforesaid clinical conditions in mammals, including humans.
The compounds of the present invention are also of value in the treatment of a combination of the above conditions, in particular in the treatment of combined post-operative pain and post-operative nausea and vomiting.
The compounds of the present invention are particularly useful in the treatment of nausea or emesis, including acute, delayed, post-operative, late-phase, and anticipatory emesis, such as emesis or nausea induced by for example chemotherapy, radiation, surgery, migraine, toxins, such as metabolic or microbial toxins, viral or bacterial infections, pregnancy, vestibular disorder, motion, mechanical stimulation, gastrointestinal obstruction, reduced gastrointestinal motility, visceral pain, psychological stress or disturbance, high altitude, weightlessness, opioid analgesics, intoxication, resulting for example from consumption of alcohol, and variations in intercranial pressure. Most especially, this compounds is of use in the treatment of emesis induced by antineoplastic (cytotoxic) agents including those routinely used in cancer chemotherapy.
Examples of such chemotherapeutic agents include alkylating agents, for example, nitrogen mustards, ethyleneimine compounds, alkyl sulfonates and other compounds with an alkylating action such as nitrosoureas, cisplatin, and dacarbazine; antimetabolites, for example, folic acid, purine or pyrimidine antagonists; mitotic inhibitors, for example, vinca alkaloids and derivatives of podophyllotoxin; and cytotoxic antibiotics. Particular examples of chemotherapeutic agents are described, for example, by D J Stewart in “Nausea and Vomiting: Recent Research and Clinical Advances”, Eds. J. Kucharczyk et al., CRC Press Inc., Boca Raton, Fla., USA (1991), pages 177-203. Commonly used chemotherapeutic agents include cisplatin, dacarbazine, mechlorethamine, streptozocin, cyclophosphamide, carmustine, lomustine, doxorubicin, daunorubicin, procarbazine, mitomycin, cytarabine, etoposide, methotrexate, 5-fluorouracil, vinblastine, vincristine, bleomycin, and chlorambucil (Gralla et al., Cancer Treatment Reports 68, 163-172, 1984).
The compounds of the present invention are also of use in the treatment of emesis induced by radiation including radiation therapy such as in the treatment of cancer, or radiation sickness, and in the treatment of post-operative nausea and vomiting.
Further, the compounds of the present invention can act as calcium channel blocking agents. As such, the compounds of the present invention are useful in the prevention or treatment of clinical conditions which benefit from inhibition of the transfer of calcium ions across the plasma membrane of cells. These include diseases and disorders of the heart and vascular system such as angina pectoris, myocardial infarction, cardiac arrhythmia, cardiac hypertrophy, cardiac vasospasm, hypertension, cerebrovascular spasm and other ischemic disease. Furthermore, these compounds may be capable of lowering elevated intraocular pressure when administered topically to the hypertensive eye in solution in a suitable ophthalmic vehicle. Also, these compounds may be useful in the reversal of multidrug resistance in tumor cells by enhancing the efficacy of chemotherapeutic agents. In addition, the compounds may have activity in blocking calcium channels in insect brain membranes and so may be useful as insecticides.
The compounds of the present invention are particularly useful in the treatment of pain or nociception and/or inflammation and disorders associated therewith such as, for example: neuropathy, such as diabetic or peripheral neuropathy and chemotherapy-induced neuropathy; postherpetic and other neuralgias; asthma; osteoarthritis; rheumatoid arthritis; and especially migraine. The compounds of the present invention are also particularly useful in the treatment of diseases characterized by neurogenic mucus secretion, especially cystic fibrosis.
The compounds of the present invention may be used singularly, as a combination of two or more compounds, in combination with other known inhibitors of inflammation, in combination with other known inhibitors of central nervous disorders, or in combination with known inhibitors of other disorders. For example the compounds of this invention may be used therapeutically with corticosteroids, non-steroidal anti-inflammatory agents, COX-2 inhibitors, matrix metalloprotease inhibitors or lipoxygenase inhibitors. The compounds of the invention can be administered in such oral forms as tablets, capsules (each of which includes sustained release or timed release formulations), pills, powders, granules, elixers, tinctures, suspensions, syrups, and emulsions. Likewise, they may be administered in intravenous (bolus or infusion), intraperitoneal, subcutaneous, intranasal, intrarectal or intramuscular form, all using forms well known to those of ordinary skill in the pharmaceutical arts. The compounds may be administered intraocularly or topically as well as orally or parenterally.
The compounds of this invention may be administered by inhalation, and thus may be delivered in the form of an aerosol spray from pressurized packs or nebulizers. The compounds may also be delivered as powders which may be formulated and the powder composition may be inhaled with the aid of an insufflation powder inhaler device. A preferred delivery system for inhalation is the metered dose inhalation aerosol, which may be formulated as a suspension or solution of a compound of the invention in suitable propellants, such as fluorocarbons or hydrocarbons. Another preferred delivery system is the dry powder inhalation aerosol, which may be formulated as a dry powder of a compound of this invention with or without additional excipients.
The compounds of the invention can be administered in the form of a depot injection or implant preparation which may be formulated in such a manner as to permit a sustained release of the active ingredient. The active ingredient can be compressed into pellets or small cylinders and implanted subcutaneously or intramuscularly as depot injections or implants. Implants may employ inert materials such as biodegradable polymers or synthetic silicones, for example, Silastic, silicone rubber or other polymers manufactured by the Dow-Coming Corporation.
The compounds of the invention can also be administered in the form of liposome delivery systems, such as small unilamellar vesicles, large unilamellar vesicles and multilamellar vesicles. Liposomes can be formed from a variety of phospholipids, such as cholesterol, stearylamine or phosphatidylcholines.
The compounds of this invention may also be delivered by the use of monoclonal antibodies as individual carriers to which the compound molecules are coupled. The integrin or neurokinin inhibitors may also be coupled with soluble polymers as targetable drug carriers. Such polymers can include polyvinlypyrrolidone, pyran copolymer, polyhydroxy-propyl-methacrylamide-phenol, polyhydroxyethyl-aspartamide-phenol, or polyethyleneoxide-polylysine substituted with palmitoyl residues. Furthermore, the integrin or neurokinin inhibitors may be coupled to a class of biodegradable polymers usefuil in achieving controlled release of a drug, for example, polylactic acid, polyglycolic acid, copolymers of polylactic and polyglycolic acid, polyepsilon caprolactone, polyhydroxy butyric acid, polyorthoesters, polyacetals, polydihydropyrans, polycyanoacrylates and cross linked or amphipathic block copolymers of hydrogels.
The pharmaceutical compositions of this invention may be used in the form of a pharmaceutical preparation, for example in solid, semisolid or liquid form, which contains one or more of the compounds of the present invention, as an active ingredient, in admixture with an organic or inorganic carrier or excipient suitable for external, enteral or parenteral applications. The active ingredient may be compounded, for example, with the usual non-toxic, pharmaceutically acceptable carriers for tablets, pellets, capsules, suppositories, solutions, emulsions, suspensions, and any other form suitable for use. The carriers which can be used are water, glucose, lactose, gum acacia, gelatin, mannitol, starch paste, magnesium trisilicate, talc, corn starch, keratin, colloidal silica, potato starch, urea and other carriers suitable for use in manufacturing preparation, in solid, semisolid, or liquid form, and in addition auxiliary, stabilizing, thickening and coloring agents and perfumes may be used. The active object compounds is included in the pharmaceutical composition in an amount sufficient to produce the desired effect upon the process or condition of the disease.
For preparing solid compositions such as tablets, the principal active ingredient is mixed with a pharmaceutical carrier; conventional tableting ingredients such as corn starch, lactose, sucrose, sorbitol, talc, stearic acid, magnesium stearate, dicalcium phosphate or gums, and other pharmaceutical diluents; water, to from a solid preformulation composition containing homogeneous mixture of a compound of the present invention, or a non-toxic pharmaceutically acceptable salt thereof. When referring to these preformulation compositions as homogeneous, it is meant that the active ingredient is dispersed evenly throughout the composition so that the composition may be readily subdivided into equally effective unit dosage forms such as tablets, pills and capsules. This solid preformulation composition is then subdivided into unit dosage forms of the type, described above containing from 0.1 to about 500 mg of the active ingredient of the present invention. The tablets or pills of the novel composition can be coated or otherwise compounded to provide a dosage form affording the advantage of prolonged action. For example, the tablet or pill can comprise an inner dosage and an outer dosage component, the latter being in the form of an envelope over the former. The two components can be separated by an enteric layer which serves to resist disintegration in the stomach and permits the inner component to pass intact into the duodenum or to be delayed in release. A variety of materials can be used for such enteric layers coatings, such materials including a number of polymeric acids and mixtures of polymeric acids with such materials as shellac, acetyl alcohol and cellulose acetate.
The liquid forms in which the compositions of the present invention may be incorporated for administration orally or by injection include aqueous solution, suitably flavored syrups, aqueous or oil suspensions, and emulsions with acceptable oils such as cottonseed oil, sesame oil, coconut oil or peanut oil, or with solubilizing or emulsifying agent suitable for intravenous use, as well as elixirs and similar pharmaceutical vehicles. Suitable dispersing or suspending agents for aqueous suspensions include synthetic and natural gums such as tragacanth, acacia, alginate, dextran, sodium carboxymethylcellulose, methylcellulose, polyvinylpyrrolidone or gelatin.
Compositions for inhalation of insufflation include solutions and suspensions in pharmaceutically acceptable, aqueous or organic solvents, or mixtures thereof, and powders. The liquid or solid compositions may contain suitable pharmaceutically acceptable excipients as set out above. Preferably the compositions are administered by the oral or nasal respiratory route for local or systemic effect. Compositions in preferably sterile pharmaceutically acceptable solvents may be nebulized by use of inert gases. Nebulized solutions may be breathed directly form the nebulizing device or the nebulizing device may be attached to a face mask, tent or intermittent positive pressure breathing machine. Solution, suspension or powder compositions may be administered, preferably orally of nasally, from devices which deliver the formulation in an appropriate manner.
For the treatment of the clinical conditions and diseases noted above, the compounds of this invention may be administered orally, topically, parenterally, by inhalation spray or rectally in dosage unit formulations containing conventional non-toxic pharmaceutically acceptable carriers, adjuvants and vehicles. The term parenteral as used herein includes subcutaneous injections, intravenous, intramuscular, intrastemal injection or infusion techniques.
For the treatment of certain conditions it may be desirable to employ a compound of the present invention in conjunction with another pharmacologically active agent. For example, a compound of the present invention may be presented together with another therapeutic agent as a combined preparation for simultaneous, separate, or sequential use for the relief of emesis. Such combined preparations may be, for example, in the form of a twin pack. A preferred combination comprises a compound of the present invention with a chemotherapeutic agent such as an alkylating agent, antimetabolite, mitotic inhibitor, or cytotoxic antibiotic, as described above. In general, the currently available dosage forms of the known therapeutic agents for use in such combinations will be suitable.
Similarly, for the treatment of respiratory diseases, such as asthma, a compound of the present invention may be used in conjunction with a bronchodilator, such as a β₂-adrenergic receptor agonist of a tachykinin antagonist which acts at neurokinin-2 receptors. Also, for the treatment of conditions that require antagonism of both neurokinin-1 and neurokinin-2, including disorders associated with bronchoconstriction and/or plasma extravasation in airways, such as asthma, chronic bronchitis, airways disease, or cystic fibrosis, a compound of the present invention may be used in conjunction with a tachykinin antagonist which acts at neurokinin-2 receptors, or with tachykinin receptor antagonist which acts at neurokinin-1, neurokinin-2, and neurokinin-3 receptors. Similarly, for the prevention of treatment of emesis a compound of the present invention may be used in conjunction with other anti-emetic agents, especially 5HT₃receptor antagonists, such as ondansetron, granisetron, tropisetron, decadron, zatisetron, as well as other commercially and naturally available pharmacologically active agents. Likewise, for the prevention or treatment of migraine a compound of the present invention may be used in conjunction with other anti-migraine agents, such as ergotamines or 5HT₃agonists, especially sumatriptan. Likewise, for the treatment of behavioral hyperalgesia, a compound of the present invention may be used in conjunction with an antagonist of N-methyl D-asparatate (NMDA), such as dizocilpine. For the prevention of treatment of inflammatory conditions in the lower urinary tract, especially cystitis, a compound of the present invention may be used in conjunction with an antiinflammatory agent, such as a bradykinin receptor antagonist. The compound of the present invention and the other pharmacologically active agent may be administered to a patient simultaneously, sequentially or in combination.
The compounds of this invention may be administered to patients (animals and humans) in need of such treatment in dosages that will provide optimal pharmaceutical efficacy. It will be appreciated that the dose required for use in any particular application will vary from patient to patient, not only with the particular compound or composition selected, but also with the route of administration, the nature of the condition being treated, the age and condition of the patient, concurrent medication of special diets then being followed by patient, and other factors which those skilled in the art will recognize, with the appropriate dosage ultimately being at the discretion of the attendant physician.
In the treatment of a condition associated with an excess of tachykinins, an appropriate dosage level will generally be about 0.001 to 50 mg per kg patient body weight per day which may be administered in single or multiple doses. Preferably, the dosage level will be about 0.01 to about 25 mg/kg per day; more preferably about 0.05 to about 10 mg/kg per day. For example, in the treatment of conditions involving the neurotransmission of pain sensations, a suitable dosage level is about 0.001 to 25 mg/kg per day, preferably about 0.05 to 10 mg/kg per day, and especially about 0.1 to 5 mg/kg per day. A compound may be administered on a regimen of 1 to 4 times per day, preferably once or twice per day. In the treatment of emesis using an injectable formulation, a suitable dosage level is about 0.001 to 10 mg/kg per day, preferably about 0.005 to 5 mg/kg per day, and especially about 0.05 to 5 mg/kg per day, A compound may be administered on a regiment of 1 to 4 times per day, preferably once or twice per day.
The dose and method of administration can be tailored to achieve optimal efficacy but will depend on such factors as weight, diet, concurrent medication and other factors which those skilled in the medical arts will recognize. When administration is to be parenteral, such as intravenous on a daily basis, injectable pharmaceutical compositions can be prepared in conventional forms, either as liquid solutions or suspensions, solid forms suitable for solution or suspension in liquid prior to injection, or as emulsions.
Tablets suitable for oral administration of active compounds of the invention can be prepared as follows:

Amount-mg

Active Compound 25.0 50.0 100.0

Microcrystalline cellulose 37.25 100.0 200.0

Modified food corn starch 37.25 4.25 8.5

Magnesium stearate 0.50 0.75 1.5
All of the active compound, cellulose, and a portion of the corn starch are mixed and granulated to 10% corn starch paste. The resulting granulation is sieved, dried and blended with the remainder of the corn starch and the magnesium stearate. The resulting granulation is then compressed into tablets containing 25.0, 50.0, and 100.0 mg, respectively, of active ingredient per tablet.
An intravenous dosage form of the above-indicated active compounds may be prepared as follows:

Active Compound 0.5-10.0 mg

Sodium Citrate 5-50 mg

Citric Acid 1-15 mg

Sodium Chloride 1-8 mg

Water for Injection (USP) q.s. to 1 ml
Utilizing the above quantities, the active compound is dissolved at room temperature in a previously prepared solution of sodium chloride, citric acid, and sodium citrate in water for injection (USP, see page 1636 of United States Pharmacopoeia/National Formulary for 1995, published by United States Pharmacopoeia Convention, Inc., Rockville, Md., copyright 1994).

EXAMPLES

The following examples are provided for purposes of illustration, not limitation. These examples illustrate the syntheses of reverse-turn mimetics of this invention. Specifically, the preparation of reverse-turn mimetics was carried out on solid phase. The solid phase syntheses of these reverse-turn mimetics demonstrate that libraries containing such members may be readily prepared.

TABLE 1


Abbreviations used in Figures and Examples

Reagents:

AcOH	acetic acid
BOP	Benzotriazol-1-yloxy-tris(dimethylamino)phosphonium
	hexafluorophosphate
DIAD	diisoproppyl azodicarboxylate
DIEA	N,N-diisopropylethylamine
HATU	O-(7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyluronium
	hexafluorophosphate
HOBt	1-hydroxybenzotriazole hydrate
TFA	trifluoroacetic acid
TPP	triphenylphosphine

Solvents:

DCM	dichloromethane
THF	tetrahydrofuran
DMF	dimethylformamide
DMSO	dimethylsulfoxide

Others:

Dess-Martin	Dess-Martin periodinane
Fmoc	9-fluorenylmethoxy carbonyl
LC/MS	HPLC/Mass spectrometry
rt	room temperature

The reactions were carried out in (but not limited to) the following: plastic disposable syringes of the appropriate size, each fitted with a polypropylene frit to retain the resin, 1-10 ml reaction vessel compatible with Symphony Automated Peptide Synthesizer (Protein Technologies), ACT 90 Synthesizer (Advanced ChemTech), Robbins block, or IRORI system.

Example 1

Modular Solid Phase Synthesis of Intermediates

This example is directed to a number of different methods for generating the intermediates on resins with different linkers in a modular fashion and coupling component pieces sequentially to produce the first, second, and third intermediates followed by cleavage and cyclization to form the reverse-turn mimetics of the present invention.
Solid Phase Synthesis of Representative Intermediate (1):

Solid Phase Synthesis of Representative Intermediate (2):

Solid Phase Synthesis of Representative Intermediate (3):

Representative Cleavage and Cyclization of Intermediate (3)

Example 2

Synthesis of a Representative Reverse-Turn Mimetic (II)

The solid phase synthesis is illustrated in FIG. 1. Referring to this figure, commercially available p-alkyloxybenzyl alcohol resin (Wang resin) was treated with p-nitrophenyl chloroformate and pyridine in DCM at 0° C. for 12 hours to give p-nitrophenyl carbonate resin. Reaction of the p-nitrophenyl carbonate resin with diamine in DMF gave the corresponding aminoalkyl resin.
Next, the resin bearing the free amino group was acylated with FmocNH-B-COOH in the presence of BOP, HOBt, and DIEA in DMF. Subsequently, the Fmoc protection was removed by treatment with a 25% (v/v) piperidine/DMF solution over 10-20 minutes.
The resin was then reacted with a second FmocNH-A—COOH in the presence of BOP, HOBt, and DIEA in DMF. The resin was again treated with 25% (v/v) piperidine/DMF solution over 10-20 minutes to remove the Fmoc protection group.
The deprotected resin was first washed with 2% AcOH in DMF and then treated with solution of aldehyde (R₁CHO) in 2% AcOH in DMF for 2 hours. The resin was washed with solution of 2% AcOH in DMF and further treated with NaBH₃CN in 2% AcOH in DMF for 3 hours and then neutralized with DIEA/DCM.
Finally, the resin bound (R₁—NH-A—C(O)—NH—B—C(O)—NH—R₄—NHC(O)—O-Pol) sequence was terminated by reaction with crotonic acid in the presence of HATU and DIEA in DMF for 60 minutes. Completion of acylation was checked by chloranile test. Crotonamide resin was than transformed to glyoxylic amide resin using solution of 10% tetrabutylammonium periodate in DCM and catalytic amount of osmium tetroxide at rt. for 24 hours.
The compound was then simultaneously removed from the resin and cyclized to form the final product by treatment with formic acid at 60° C. for 12 hours or an extended reaction time when necessary to complete the cyclization. Alternatively, the compound was cleaved from the resin by treatment with 95% aqueous TFA for 30-60 minutes. The residue obtained after evaporation of formic acid was reconstituted in AcOH and lyophilized. Cyclization was then performed by redissolving the dry product in TFA and heating at 60° C. overnight or in neat TFA at rt. overnight. The residue obtained after evaporation of formic acid or TFA was redissolved in AcOH mixture, frozen and lyophilized.

Example 3

Synthesis of a Representative Reverse-Turn Mimetic (II)

The solid phase synthesis is illustrated in FIG. 2. Referring to this figure, commercially available p-alkyloxybenzyl alcohol resin (Wang resin) was treated with p-nitrophenyl chloroformate and pyridine in DCM at 0° C. for 12 hours to give p-nitrophenyl carbonate resin. Reaction of the p-nitrophenyl carbonate resin with diamine in DMF gave the corresponding aminoalkyl resin.
Next, the resin bearing the free amino group was acylated with FmocNH-B—COOH in the presence of BOP, HOBt, and DIEA in DMF. Subsequently, the Fmoc protection was removed by treatment with a 25% (v/v) piperidine/DMF solution over 10-20 minutes.
The resin was then reacted with a second FmocNH-A—COOH in the presence of BOP, HOBt, and DIEA in DMF. The resin was again treated with 25% (v/v) piperidine/DMF solution over 10-20 minutes to remove the Fmoc protection group.
The deprotected resin was first washed with 2% AcOH in DMF and then treated with solution of aldehyde (R₁CHO) in 2% AcOH in DMF for 2 hours. The resin was washed with solution of 2% AcOH in DMF and further treated with NaBH₃CN in 2% AcOH in DMF for 3 hours and then neutralized with DIEA/DCM.
Finally, the resin bound (R₁—NH-A—C(O)—NH—B—C(O)—NH—R₄-NHC(O)—O-Pol) sequence was terminated by reaction with acetoxyacetyl chloride (AcOAcCl) (4%) and DIEA (8%) in DCM for 20 minutes. Completion of acylation was checked by chloranile test. Acetate protecting group was then removed by treatment with solution of 33% methyl amine in ethanol for 2 hours. Hydroxy group was then oxidized using Dess-Martin reagent in DMSO for 2 hours.
The compound was then simultaneously removed from the resin and cyclized to form final product by treatment with formic acid at 60° C. for 12 hours or an extended reaction time when necessary to complete the cyclization. Alternatively, the compound was cleaved from the resin by treatment with 95% aqueous TFA for 30-60 minutes. The residue obtained after evaporation of formic acid was reconstituted in AcOH and lyophilized. Cyclization was then performed by redissolving the dry product in formic acid and heating at 60° C. overnight or in neat TFA at rt. overnight. The residue obtained after evaporation of formic acid or TFA was redissolved in AcOH mixture, frozen and lyophilized.

Example 4

Synthesis of a Representative Reverse-Turn Mimetic (X)

The solid phase synthesis is illustrated in FIG. 3. Referring to this figure, commercially available p-alkyloxybenzyl alcohol resin (Wang resin) was acylated with FmocNH-B-COOH in the presence of TPP and DIEA in THF. Subsequently, the Fmoc protection was removed by treatment with a 25% (v/v) piperidine/DMF solution over 10-20 minutes.
The resin was then reacted with a second FmocNH-A—COOH in the presence of BOP, HOBt, and DIEA in DMF. The resin was again treated with 25% (v/v) piperidine/DMF solution over 10-20 minutes to remove the Fmoc protection group.
The deprotected resin was first washed with 2% AcOH in DMF and then treated with solution of aldehyde (R₁CHO) in 2% AcOH in DMF for 2 hours. The resin was washed with solution of 2% AcOH in DMF and further treated with NaBH₃CN in 2% AcOH in DMF for 3 hours and then neutralized with DIEA/DCM.
Finally, the resin bound (R₁—NH-A—C(O)—NH—B—C(O)—O-Pol) sequence was terminated by reaction with crotonic acid in the presence of HATU and DIEA in DMF for 60 minutes. Completion of acylation was checked by chloranile test. Crotonamide resin was than transformed to glyoxylic amide resin using solution of 10% tetrabutylammonium periodate in DCM and catalytic amount of osmium tetroxide at rt. for 24 hours.
The compound was then simultaneously removed from the resin and cyclized to form final product by treatment with formic acid at 60° C. for 12 hours or an extended reaction time when necessary to complete the cyclization. Alternatively, the compound was cleaved from the resin by treatment with 95% aqueous TFA for 30 - 60 minutes. The residue obtained after evaporation of formic acid was reconstituted in AcOH and lyophilized. Cyclization was then performed by redissolving the dry product in TFA and heating at 60° C. overnight or in neat TFA at rt. overnight. The residue obtained after evaporation of formic acid or TFA was redissolved in AcOH mixture, frozen and lyophilized.

Example 5

Synthesis of a Representative Reverse-Turn Mimetic (X)

The solid phase synthesis is illustrated in FIG. 4. Referring to this figure, commercially available methylbenzhydryl amine resin was acylated with FmocNH—B—COOH in the presence of TPP and DIEA in THF. Subsequently, the Fmoc protection was removed by treatment with a 25% (v/v) piperidine/DMF solution over 10-20 minutes.
The resin was then reacted with a second FmocNH-A—COOH in the presence of BOP, HOBt, and DIEA in DMF. The resin was again treated with 25% (v/v) piperidine/DMF solution over 10-20 minutes to remove the Fmoc protection group.
The deprotected resin was first washed with 2% AcOH in DMF and then treated with solution of aldehyde (R₁CHO) in 2% AcOH in DMF for 2 hours. The resin was washed with solution of 2% AcOH in DMF and further treated with NaBH₃CN in 2% AcOH in DMF for 3 hours and then neutralized with DIEA/DCM.
Finally, the resin bound (R₁—NH-A—C(O)—NH—B—C(O)—NH-Pol) sequence was terminated by reaction with acetoxyacetyl chloride (AcOAcCl) (4%) and DIEA (8%) in DCM for 20 minutes. Completion of acylation was checked by chloranile test. Acetate protecting group was then removed by treatment with solution of 33% methyl amine in ethanol for 2 hours. Hydroxy group was then oxidized using Dess-Martin reagent in DMSO for 2 hours.
The compound was then simultaneously removed from the resin and cyclized to form final product by treatment with formic acid at 60° C. for 12 hours or an extended reaction time when necessary to complete the cyclization. Alternatively, the compound was cleaved from the resin by treatment with 95% aqueous TFA for 30-60 minutes. The residue obtained after evaporation of formic acid was reconstituted in AcOH and lyophilized. Cyclization was then performed by redissolving the dry product in TFA and heating at 60° C. overnight or in neat TFA at rt. overnight. The residue obtained after evaporation of formic acid or TFA was redissolved in AcOH mixture, frozen and lyophilized.

Example 6

The Synthesis of Representative Reverse-Turn Mimetics

Representative compounds of this invention were synthesized according to the above procedures.

TABLE 2


REPRESENTATIVE COMPOUNDS OF STRUCTURE TYPE (XV)

	(XV)

Cpd. No.	R₁	R₂	R₃


1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29


30

31

32

33

34

TABLE 3


REPRESENTATIVE COMPOUNDS OF STRUCTURE TYPE (VII)

	(VII)

Cpd. No	R₁	R₂	R₃	R₄


35

36

37	H₃C—X₁

38	H₃C—X₁

39	H₃C—X₁

40

41

42

43

44

TABLE 4


FURTHER REPRESENTATIVE COMPOUNDS

Cpd.
No


45

46

47

48

49

50

TABLE 5


ANALYTICAL DATA FOR REPRESENTATIVE COMPOUNDS

Cpd	Method of	LC RT^‡	MS
No.	Synthesis⁺	(min)	(M + H⁺)

1	A2, B1, C2, D1	1.09 (A)	456.1
2	A2, B1, C2, D1	1.23 (A)	516.1
3	A2, B1, C2, D1	1.31 (A)	488.2
4	A2, B1, C2, D1	1.13 (A)	516.1
5	A2, B1, C2, D1	1.01 (A)	456.2
6	A2, B1, C2, D1	1.21 (A)	488.2
7	A2, B1, C2, D1	1.29 (A)	468.2
8	A2, B1, C2, D1	1.46 (A)	498.2
9	A2, B1, C2, D1	1.18 (A)	484.2
10	A2, B1, C2, D1	1.30 (A)	440.2
11	A2, B1, C2, D1	1.40 (A)	470.2
12	A2, B1, C2, D1	1.13 (A)	456.2
13	A2, B1, C2, D1	1.47 (A)	450.2
14	A2, B3, C2, D1	1.58 (A)	317.0
15	A2, B3, C2, D1	1.81 (A)	331.1
16	A2, B3, C2, D1	0.74 (A)	346.1
17	A2, B3, C2, D1	1.10 (A)	347.1
18	A2, B3, C2, D1	0.89 (A)	240.9
19	A2, B3, C2, D1	1.26 (A)	255.0
20	A2, B3, C2, D1	0.21 (A)	270.0
21	A2, B3, C2, D1	1.40 (A)	271.0
22	A2, B3, C2, D1	1.85 (A)	550.9
23	A1, B1, C2, D1	1.74 (A)	565.0
24	A2, B1, C2, D1	2.14 (A)	563.1
25	A2, B1, C2, D1	2.23 (A)	615.1
26	A2, B2, C2, D2	1.62 (A)	756.7
27	A2, B2, C2, D2	1.26 (A)	485.8
28	A2, B3, C2, D2	1.29 (A)	476.8
29	A2, B3, C2, D1	0.19 (A)	242.1
30	A2, B2, C2, D1	0.19 (A)	268.1
31	A2, B3, C2, D1	1.72 (A)	359.0
32	A2, B3, C2, D1	1.85 (A)	373.1
33	A2, B3, C2, D1	1.01 (A)	388.1
34	A2, B3, C2, D1	1.14 (A)	389.1
35	A2, B1, C2, D1	3.32 (B)	574.3
36	A1, B1, C2, D1	3.61 (B)	561.0
37	A5, B3, C2, D1	1.03 (A)	387.3
38	A2, B1, C2, D1	0.99 (A)	373.3
39	A5, B3, C2, D1	1.28 (A)	463.2
40	A1, B1, C2, D1	1.10 (A)	538.3
41	A1, B1, C2, D1	0.94 (A)	486.3
42	A1, B1, C2, D1	1.21 (A)	514.4
43	A1, B1, C2, D1	1.16 (A)	548.3
44	A1, B1, C2, D1	1.17 (A)	514.3
45	A1, B3, C1, D2	3.12 (B)	315.1
46	A5, B3, C2, D2	1.27 (A)	331.0
47	A1, B1, C2, D2	3.76 (B)	477.2
48	A2, B1, C2, D1	2.90 (B)	574.3
49	A1, B1, C2, D1	3.42 (B)	561.0
50	A5, B3, C2, D1	1.10 (A)	399.3

⁺The methods of synthesis using the modular approach is as described in Example 1.
^‡LCMS analysis was performed on reverse-phase C₁₈Zorbax columns using the following solvent system: A, water with 0.1% formic acid; B, acetonitrile with 0.1% formic acid. The following conditions were applied: (A) column 2.1 × 30 mm, 5-95% B in 4 min, flow 0.3 ml/min. (B) column 5 um 4.6 × 50 mm, 5-90% B in 5 min, flow 1.5 ml/min. Mass spectra for separated peaks were obtained by electrospray (ES) using a MicroMass LCZ mass spectrometer.

Example 7

The Synthesis of Representative Reverse-Turn Mimetics

This example illustrates the synthesis of further representative reverse-turn mimetics of this invention.
Compound of structure (XIX′) was synthesized according to the above procedure of Example 1 (A1,B3,C1,D2) using commercially available methylbenzhydryl amine resin. In brief, commercially available methylbenzhydryl amine resin was acylated with Fmoc-Phe followed by Fmoc-Pro coupling. The resin bound (Pro-Phe—NH-Pol) sequence was terminated by reaction with 2-methylcrotonic acid. Subsequent treatment with osmium tetroxide/tetrabutylammonium periodate followed by simultaneous removal from the resin and cyclization to form the final product (XIX′). ¹H NMR was carried out on HPLC purified product of this mimetic and spectra were assigned by combination of ID and 2D DQF-COSY, TOCSY, and ROESY experiments. All spectra were consistent with the structure indicated above. ¹H NMR (500 MHz, 10:1 CD₃OD:CDCl₃, −20 C, ppm): δ 7.34 (2 H, dd, ArH), 7.30 (1 H, t, ArH), 7.16 (2 H, d, ArH), 4.81 (1 H, dd, J=2.7, 5.8 Hz), 4.45 (1 H, dd, J=6.9, 9.15 Hz), 3.48 (1 H, m), 3.32 (1 H, m), 2.32 (1 H, m), 2.12 (1 H, m), 2.05 (1 H, m), 1.93 (1 H, m), 0.65 (3 H, s). MS (ES+): m/z 315.1 [M+H]⁺·RP-HPLC (C-18 semi-preparative, 7.8×300 mm): A:0.1% TFA/H₂O, B: 0.1% TFA/CH₃CN, gradient 15-45% B/25 min, 4 ml/min, 215 nm, tR 21.6′.

Example 8

The Synthesis of Representative Reverse-Turn Mimetics

This example illustrates the synthesis of further representative reverse-turn mimetics of this invention.
Compound of structure (VII′) was synthesized according to the above procedure of Example 3 using appropriate amino acids, aldehyde and linker. ¹H NMR was carried out on HPLC purified product of this mimetic and spectra were assigned by combination of 1D and 2D DQF-COSY, TOCSY, and ROESY experiments. All spectra were consistent with the structure indicated above. ¹H NMR (500 MHz, CD₃OD, −20 C, ppm): δ 7.32-7.28 (2 H, ArH), 7.24-7.19 (3 H, ArH), 6.95 (2 H. d, ArH), 6.75 (2 H. d, ArH), 4.29 (1 H, t, J=4.4 Hz), 4.20 (1 H, q), 3.93 (1 H, m), 3.72 (1 H, dd, J=8.2, 13.5 Hz), 3.27 (1 H, dd, J=3.1, 14.1 Hz), 3.20 (1 H, s), 3.13 (2 H, dq), 2.91 (2 H, t, J=7.6 Hz), 2.86 (1 H, dd, J=6.87, 13.7 Hz), 2.62-2.55 (2 H, m), 2.45 (2 H. b), 1.78-1.60 (7 H, bm), 1.52 (1 H, bd), 1.34-1.14 (7 H, bm), 1.03-0.90 (2 H, bm). MS (ES+): m/z 561.3 [M+H]⁺. RP-HPLC (C-18 semi-preparative, 7.8×300 mm): A:0.1% TFA/H₂O, B: 0.1% TFA/CH₃CN, gradient 40% B/25 min, 4 ml/min, 215 nm, tR 7.84′.

Example 9

The Synthesis of Representative Reverse-Turn Mimetics

This example illustrates the synthesis of further representative reverse-turn mimetics of this invention.
Compound of structure (VII″) was synthesized according to the above procedure of Example 3 using appropriate amino acids, aldehyde and linker. ¹H NMR was carried out on HPLC purified product of this mimetic and spectra were assigned by combination of ID and 2D DQF-COSY, TOCSY, and ROESY experiments. All spectra were consistent with the structure indicated above. ¹H NMR (500 MHz, CD₃OD, −20 C, ppm): δ 7.35 (2 H, t, ArH), 7.28 (1 H, t, ArH), 7.19 (2 H, d, ArH), 7.03 (2 H, d, ArH), 6.85 (2 H, d, ArH), 4.80 (1 H, m), 4.39 (1 H, t, J=4.2 Hz), 3.96 (1 H, m), 3.77 (1 H, dd, J=8.4, 13.7 Hz), 3.31 (1 H, s), 3.19 (2 H, d, J=4.6 Hz), 2.98-2.90 (4 H, m), 2.59 (1 H, m), 2.35-2.27 (2 H, m), 2.165 (1 H, dd, J=2.29, 16.8 Hz), 1.79-1.64 (7 H, bm), 1.62-1.52 (2 H, bm), 1.38-1.31 (2 H, m), 1.30-1.18 (4 H, bm), 1.08-0.90 (2 H, bm). MS (ES+): m/z 561.0 [M+H]⁺. RP-HPLC (C-18 semi-preparative, 7.8×300 mm): A:0.1% TFA/H₂O, B: 0.1% TFA/CH₃CN, gradient 30-50% B/25 min, 4 ml/min, 215 nm, tR 14.94′.

Example 10

The Synthesis of Representative Reverse-Turn Mimetics

This example illustrates the synthesis of further representative reverse-turn mimetics of this invention.
Compound of structure (XV′) was synthesized according to the above procedure of Example 5 using appropriate amino acids, aldehyde and linker. ¹H NMR was carried out on HPLC purified product of this mimetic and spectra were assigned by combination of 1D and 2D DQF-COSY, TOCSY, and ROESY experiments. All spectra were consistent with the structure indicated above. ¹H NMR (500 MHz, CD₃OD, 22 C, ppm): δ 7.40-7.05 (10 H, ArH), 4.42 (1 H, t, J=6.9 Hz), 4.37 (1 H, t, J=5.0 Hz), 4.13 (1 H, s), 4.04 (1 H, m), 3.27 (1 H, dd, J=5.34, 15.0 Hz), 3.13 (2 H, m), 2.95 (2 H, t, J=7.63 Hz), 2.70 (2 H, m), 2.04 (2 H, p), 1.72 (4 H, m), 1.46 (2 H, m). MS (ES+): m/z 450.2 [M+H]⁺. RP-HPLC (C-18 semi-preparative, 7.8×300 mm): A:0.1% TFA/H₂O, B: 0.1% TFA/CH₃CN, gradient 30-50% B/20 min, 4 ml/min, 215 nm, tR 12.67′.

Example 11

The Synthesis of Representative Reverse-Turn Mimetics

This example illustrates the synthesis of further representative reverse-turn mimetics of this invention.
Compound of structure (XVI′) was synthesized according to the above procedure of Example 2 using appropriate amino acids, aldehyde and linker. ¹H NMR was carried out on HPLC purified product of this mimetic and spectra were assigned by combination of 1D and 2D DQF-COSY, TOCSY, and ROESY experiments. All spectra were consistent with the structure indicated above. ¹H NMR (500 MHz, CD₃OD, 25 C, ppm): δ 7.27-7.20 (5 H, ArH), 7.04 (2 H, d, ArH), 6.73 (2 H, d, ArH), 5.21(1 H, s) 4.02 (1 H, dd, J=5.0, 9.9 Hz), 3.82 (1 H, dd, J=4.6, 13.3 Hz), 3.44 (1 H, dd, J=7.8, 13.9 Hz), 3.28-3.12 (4 H, m), 2.91 and 2.81 (2H, ABX, J_2.91=8.4, 13.7 Hz, J₂₈₁=6.1, 13.7 Hz), 1.80 (1 H, dd, J=7.25, 13.7 Hz), 1.66-1.56 (4 H, bm), 1.51 (1 H, m), 1.46-1.38 (2 H, bm), 1.15-1.08 (2 H, bm), 0.82-0.66 (2 H, bm). MS (ES+): m/z 477.2 [M+H]⁺. RP-HPLC (C-18 semi-preparative, 7.8×300 mm): A:0.1% TFA/H₂O, B: 0.1% TFA/CH₃CN, gradient 40% B/25 min, 4 ml/min, 215 nm, tR 19.47′.

Example 12

Integrin Biological Activity of Representative Compounds

An assay measuring the ability of compounds 1-50 to antagonize binding of CS1 peptide to αβ₁integrin was performed. A modification of the procedure of Vanderslice, P. et al. (J. Immunol., 1997, 1710-1718) (incorporated herein by reference) was utilized.
In brief, 100 μL/well of a solution of biotinylated CS1 peptide (1 mg/100 mL of phosphate buffered saline (PBS)) was incubated in a NeutrAvidin plate (Pierce) for 1 h at room temperature. The plate was then washed 3× with distilled water and treated with 200 μL of blocking buffer (3% BSA in PBS) for at least 4 h. Blocked plates were washed as above. Harvested Ramos cells (10⁷/mL) were resuspended in PBS containing 10 μL of calcein AM/mL and incubated 30 min in the dark. This suspension was diluted with 45 mL PBS and the cells harvested by centrifugation and aspiration. The cells were resuspended in binding buffer (˜5×10⁵/mL). If cell lysis was to be monitored ethidium homodimer was added to the buffer to a final concentration of 5 μM. A solution (10 μL) of compound to be tested or control peptide was added to appropriate wells followed by 90 μL of the cell suspension. The plate was incubated at 37° C. for 1 h. When ethidium homodimer was added, fluorescence at 535/617 was measured before rinsing. Otherwise, the plate was washed 3×, 50 μL of lysis buffer was added to each well, the plate rocked in the dark for 10 min, and the fluorescence monitored at 485 nm excitation and 535 nm emission.
Preferably, the compounds of this invention have an inhibition value of better than 50% at 100 μM in this assay. To this end, preferred compounds of this invention are compounds 3, 7, 8, 9, 14, 15, 21-27, 31, 32, 34, 35, 42, 45, and 47. As such, the compounds of this invention effectively inhibit cell adhesion and possess activity as anti-inflammatory agents.

Example 13

Tachykind Antagonism Assay of Representative Compounds

The compounds of this inventions are useful for antagonizing tachykinins, in particular substance P in the treatment of inflammatory diseases, central nervous system disorders, gastrointestinal disorders, pain or migraine and asthma in a mammal in need of such treatment. This activity can be demonstrated by the following assay.
An assay measuring the ability of compounds 1-50 to antagonize binding of substance P peptide to its receptor neurokinin-1 was performed. Substance P is known to act upon cells via the mobilization of calcium (Bordey et al., Glia 11: 277-283, 1994). The compounds were assessed for their ability to inhibit the action of Substance P with the use of a Fluorescent Imaging Plate Reader (FLIPR) from Molecular Devices (Shroeder et al., J. Biomol. Screening 1: 75-80, 1996; U.S. Pat. No. 5,112,134; U.S. Pat. No. 4,968,148). U373 MG cells, which endogenously express the neurokinin-1 receptor for Substance P, were obtained from the American Type Culture Collection and grown to confluence in 96-well plates in modified Eagle's minimum essential medium (MEM) with 10% fetal bovine serum, 1 mM sodium pyruvate, 2 mM L-glutamine, and 1 mM non-essential amino acids in a humidified incubator at 37 C and 5%CO₂/95% filtered air. The cells were stained with Calcium Indicator dye from Molecular Devices for thirty minutes at room temperature; compounds were added to the cells, and the cells were further incubated for twenty minutes. This dye is similar to Fluo-3, Fluo-4, and Calcium Green dyes used by other researchers (Lin et al., Biotechniques 26: 318-326, 1999) in that it increases in fluorescence in the presence of calcium; the Molecular Devices version is preferable because the cells need not be washed following staining with the dye. Dye was made fresh on the day of the assay and included 2.5 mM probenecid, an anion exchange inhibitor which helps to keep the dye retained by the cells. Substance P was added in Hank's salt solution with 1% BSA to give a final concentration of 1 nM and the resultant change in fluorescence intensity was monitored for thirty seconds with an excitation wavelength of 480 nm and an emission of 515 nm. Some wells were maintained as controls which were not incubated with any compound, and the peak fluorescence readings resulting from the wells which received compounds were compared to these control wells in order to determine the degree of inhibition.
Preferably, the compounds of this invention have an inhibition value of better than 25% at 20 μM in this assay. To this end, preferred compounds of this invention are compounds 1-7, 10, 11, 16, 25, 26, 34, 39, 40, and 45. As such, the compounds of this invention effectively inhibit cell adhesion and possess activity as anti-inflammatory agents.
It will be appreciated that, although specific embodiments of the invention have been described herein for the purposes of illustration, various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not limited except by the appended claims.

Claims

1. A method for treating a central nervous system disorder comprising administering to an animal in need thereof an effective amount of a compound having the structure:

or pharmaceutically acceptable salt or stereoisomer thereof,

wherein

A is —(CR₂R_2a)_m— where m is 1, 2 or 3;

B is —(CR₃R_3a)_n— where n is 1, 2, 3 or 4;

X is —N(R₄)—, —O—, or —S—;

R₂and R₃are, at each occurrence, the same or different and independently an amino acid side chain moiety or amino acid side chain derivative, a peptide or peptide derivative, a linker or a solid support;

R₅is an amino acid side chain moiety or amino acid side chain derivative;

R_2aand R_3aare, at each occurrence, the same or different and independently hydrogen, hydroxy, —COOH, —CONH₂, —R₆, —OR₆, —COOR₆, —COR₆or —CONHR₆, where R₆is lower alkyl optionally substituted with halogen or hydroxy;

R₁and R₄are the same or different and represent the remainder of the molecule; and

wherein R₁and R₂taken together optionally form a fused heterocycle or substituted heterocycle.

2. The method of claim 1 wherein the compound has the structure:

3. The method of claim 2 wherein the compound has the structure:

4. The method of claim 2 wherein the compound has the structure:

5. The method of claim 2 wherein the compound has the structure:

6. The method of claim 2 wherein the compound has the structure:

7. The method of claim 2 wherein the compound has the structure:

8. The method of claim 1 wherein the compound has the structure:

9. The method of claim 8 wherein the compound has the structure:

10. The method of claim 8 wherein the compound has the structure:

11. The method of claim 8 wherein the compound has the structure:

12. The method of claim 8 wherein the compound has the structure:

13. The method of claim 8 wherein the compound has the structure:

14. The method of claim 1 wherein the compound has the structure:

15. The method of claim 1 wherein the compound has the structure:

wherein R′ is one or more optional heterocycle substituents.

16. The method of claim 15 wherein the compound has the structure:

wherein R′ is —OR or —OC(O)R where R is an amino acid side chain moiety or an amino acid side chain derivative.

17. The method of claim 1 wherein R₁, R₂, R₃and R₄are the same or different and are independently an amino acid side chain moiety or an amino acid side chain derivative.

18. The method of claim 1 wherein R₁, R₂, R₃and R₄are the same or different and are independently:

(i) —H, —CH₃, —CH(CH₃)₂, —CH₂CH(CH₃)₂, —CH(CH₃)CH₂CH₃, —(CH₂)₄NH₂,

—CH₂)₃NHC(NH₂)NH₂,

—CH₂COOH, —CH₂CH₂COOH, CH₂CONH₂, —CH₂CH₂CONH₂, —CH₂SH, —CH₂CH₂SCH₃, —CH₂OH, —CH(OH)CH₃, or

(ii) a side chain moiety of 3,5-dibromotyrosine, 3,5-diiodotyrosine, hydroxylysine, γ-carboxyglutamate, phosphotyrosine, phosphothreonine or phosphoserine; or

(iii) a moiety selected from alkyl, aryl, arylalkyl, heterocyclic or heterocyclicalkyl moieties, each moiety of (iii) being optionally substituted with a substituent selected from halogen, oxo, hydroxy, haloalkyl, —R, —OR, —C(═O)R, —C(═O)OR, —C(═O)NRR, —NRR, —NRC(═O)R, —NRC(═O)OR, —NRC(═O)NRR, —OC(═O)R, —OC(═O)OR, —OC(═O)NRR, —SH, —SR, —SOR, —SO₂R, —NRSO₂R, —Si(R)₃, and —OP(OR)₃, wherein each occurrence of R is the same or different and independently an amino acid side chain moiety, hydrogen, alkyl, aryl, arylalkyl, heterocycle or heterocyclealkyl, or wherein any two R groups attached to the same nitrogen atom, taken together with the nitrogen atom to which they are attached, form a heterocyclic ring or a substituted heterocyclic ring.

19. The method of claim 1 wherein the central nervous system disorder is anxiety, depression, psychosis, schizophrenia, epilepsy, or a neurodegenerative disorder.

20. The method of claim 1 wherein the central nervous system disorder is dementia, Alzheimer's disease, Down's syndrome, or AIDS dementia.