MXPA00006499A - Heterocyclic topoisomerase poisons - Google Patents

Abstract

The invention provides compounds of formula (I) wherein R1 to R5 have any of the values defined in the specification, as well as pharmaceutically acceptable salts of the compounds, pharmaceutical compositions comprising the compounds, and methods of using the compounds, compositions, or salts to treat cancer.

Description

POISONS OF HETEROCICLIC TOPOISOMERASE Background of the Invention The DNA-topoisomerasas are enzymes present in the nuclei of the cells where they catalyze the cleavage and reunion of braids of DNA, controlling the topological state of DNA. Recent studies also suggest that topoisomerases are involved in the regulation of template supercoiling during RNA transcription. There are two main classes of mammalian topoisomerases. DNA-topoisomerase-l catalyses changes in the topological state of double DNA by performing transient-simple braid cleavage-junction cycles. In contrast, mammalian topoisomerase II alters the DNA topology by causing a double cross-braced cleavage of transient enzyme, followed by passage and braid resealing. Mammalian topoisomerase II has also been classified as Type II a and Type I I ß. The antitumor activity associated with agents which are topoisomerase poisons is associated with their abilities to stabilize the enzyme-cleavable complex by DNA-enzyme. This drug-induced stabilization of the enzyme-cleavable complex by DNA. Effectively converts the enzyme into a cell poison. Several antitumor agents in clinical use have a powerful activity as mammalian I topoisomerase poisons. These include adriamycin, acitomycin D, daunomine, VP-1 6, and VM-26 (teniposide or epipodophyllothixin).

In contrast to the number of clinical and experimental drugs which act as topoisomerase II poisons, currently there are only a limited number of agents which have been identified as topoisomerase 1 poisons. Camptothecin and its structurally related analogs are among the poisons of topoisomerase I most extensively studied. Recently, the bi- and terbenzimidazoles (Chen et al., Cancer Res., 1993, 53, 1 332-1 335; Sun et al., J. Med. Chem. 1 995, 38, 3638-3644; Kim et al. ., J. Med. Chem., 1996, 39, 992-998), some alkaloids of benzo [c] phenanthridine and protoberberin and their synthetic analogues (Makhey et al., Med. Chem. Res., 1995, 5, 1 -1 2; Janin et al., J. Med. Chem., 1975, 18, 708-713; Makhey et al., Bioorg. &Med. Chem., 1996, 4, 781-791), as well as also the fungal metabolites, bulgarin (Fujii et al., J. Biol. Chem., 1 993, 268, 1 31 60-1 31 65) and saintopin (Yamashita et al., Biochemistry, 1991, 30, 5835-5845) and indolocarbazoles (Yamashita et al., Biochemistry, 1992, 31, 1 2069-12075) Currently, there is a need for novel anti-carcinogenic agents, for anti-carcinogenic agents that exhibit improved activity, and for anti-carcinogenic agents that exhibit minor collateral effects or improved selectivity in comparison with existing agents.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a compound that exhibits inflammatory activity against topoisomerase I, and compounds that are effective cytotoxic agents against cancer cells, including cancer cells resistant to the drug. In accordance with the foregoing, a compound of the invention is provided which is a compound of the formula I: wherein Ri and R2 are each independently hydrogen, (Ci-C6) alkyl, (C3-C6) cycloalkyl, (C -C-Jalkoxy, nitro, hydroxy, haloC- C6) alkyl, trifluoromethoxy, halo, (C3-C6) ) C 1 -C 6 cycloalkyl alkyl, (C 4 -C 6) alkanoyl, hydroxy (C 6 -C 6) alkyl, (C 6 -C 6) alkoxycarbonyl, (C 6, C 6) alkylthio, (C 2 -C 6) alkanoyloxy, aryl or heteroaryl; or Rf1 and R2 taken together are methylenedioxy; or Rf and R2 taken together are benzo; wherein any aryl, heteroaryl or benzo may be optionally substituted by 1, 2 or 3 substituents independently selected from the group consisting of (C1-C6) alkyl, (C3-C6) cycloalkyl, (C1-C6) alkoxy, nitro, hydroxy, haloid-CeJalkyl, trifluoromethoxy, (C3-C6) cycloalkyl (C1-C6) alkyl, (C1-C6) alkanoyl, hydroxy (C6-6) alkyl, (C1-C6) alkoxycarbonyl, (C1-6) C6) alkylthio, (C2-C6) alkanoyloxy and halo; R3 is hydrogen, (C1-C6) alkyl, (C3-C6) cycloalkyl, (C -, - C6) alkoxy, nitro, hydroxy, halo (C1-C6) alkyl, trifluoromethoxy, halo, (C3-C6) cycloalkyl ( C1-C6) alkyl, (C1-C6) alkanoyl, hydroxy (C1-C6) alkyio, (Cr C6) alkoxycarbonyl, (C1-C6) alkylthio, (C2-C6) alkanoyloxy, or halo; and R4 and R5 taken together are a saturated chain 0 unsaturated consisting of 3, 4 or 5 members comprising members selected from the group consisting of non-peroxide oxygen, sulfur, N (X), and carbon, optionally substituted by oxo; wherein each X is independently absent or is H, O, (C1-C4) alkyl, phenyl or benzyl; and where at least one (for example, 1 or 2) of said chain members is a group N-H; or a pharmaceutically acceptable salt thereof; R4 and R5 provided, taken together are not -N (H) -C (H) = N-. Preferably, any carbon of R4 and R5 is saturated (-CH2-) or unsaturated (= CH-). The invention also provides a pharmaceutical composition comprising a compound of formula I, or a pharmaceutically acceptable salt thereof, in combination with a pharmaceutically acceptable diluent or carrier. The invention also provides a therapeutic method comprising inhibiting cancer cells when administering to a mammal (eg, a human) in need of such therapy, an amount of a compound of formula I, or a pharmaceutically acceptable salt thereof, effective to inhibit said cancer cells. The invention also provides a method comprising inhibiting cancer cells by contacting said cancer cells in vitro or in vivo with an amount of a compound of formula I, or a pharmaceutically acceptable salt thereof, effective to inhibit said cancer cells, i.e. to inhibit its activity, such as its ability to divide, migrate, or proliferate. The invention also provides a compound of formula I for use in medical therapy (preferably for use in the treatment of cancer, for example, solid tumors), as well as the use of a compound of formula I for the preparation of a medicine useful for the treatment of cancer, for example, solid tumors. The invention also provides the processes and novel intermediates described herein which are useful for preparing the compounds of the invention. Some of the compounds of the formula I are useful for preparing other compounds of the formula I.

Brief Description of the Drawings Figure 1 illustrates the synthesis of the compounds of the invention (2 and 3) and the synthesis of compound 4. Figure 2 shows the structure of compound 5.

Detailed description The following definitions are used, unless described differently: halo is fluoro, chloro, bromo or iodo. Alkyl, alkoxy, etc. denote both straight and branched groups; but the reference to an individual radical such as "propyl" embraces only the straight chain radical, a branched chain isomer such as "isopropyl" specifically referring. Aryl denotes a phenyl radical or an ortho-fused bicyclic carbocyclic radical having approximately nine to ten ring atoms in which at least one ring is aromatic. Heteroaryl embraces an attached radical through a ring carbon of a monocyclic aromatic ring containing five or six ring atoms consisting of carbon and one to four heteroatoms each selected from the group consisting of non-peroxide oxygen, sulfur and N (Y) wherein Y is absent or is H, O, (Ci-C4) alkyl, phenyl or benzyl, as well as a radical of an ortho-fused bicyclic heterocycle of about eight to ten ring atoms derived from the same, particularly a benz-derivative or a derivative by fusing a biradical of propylene, trimethylene or tetramethylene therein. It will be appreciated by those skilled in the art that compounds of the invention having a chiral center can exist in and be isolated in optically active and racemic forms. Some compounds may exhibit polymorphism. It will be understood that the present invention encompasses any racemic form, optically active, polymorphic, or stereoisomeric, or mixtures thereof, of a compound of the invention, which possesses the useful properties described herein, it being known in the art how to prepare the optically active forms (e.g. resolution of the racemic form by recrystallization techniques, by synthesis from optimally active starting materials, by chiral synthesis, or by chromatographic separation using a chiral stationary phase) and how to determine topoisomerase poisoning activity or cytotoxic activity using standard tests described herein, or using other similar tests which are well known in the art. The specific and preferred values listed below for radicals, substituents and ranges, are for illustration only; they do not exclude other defined values or other values within the ranges defined for radicals and substituents. Specifically, (C1-C6) alkyl can be methyl, ethyl, propyl, isopropyl, butyl, iso-butyl, sec-butyl, pentyl, 3-pentyl, or hexyl; (C3-C6) cycloalkyl can be cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl; (C3-C6) (C1-C6) cycloalkyl) alkyl may be cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl, cyclohexylmethyl, 2-cyclopropylethyl, 2-cyclobutylethyl, 2-cyclopentylethyl, or 2-cyclohexylethyl; (C-Cejalcoxy may be methoxy, ethoxy, propoxy, isopropoxy, butoxy, iso-butoxy, sec-butoxy, pentoxy, 3-pentoxy or hexyloxy; (Ci-Cejalcanoil may be acetyl, propanoyl, or butanoyl; halo (C? C6) alkyl can be iodomethyl, bromomethyl, chloromethyl, fluoromethyl, trifluoromethyl, 2-chloroethyl, 2-fluoroethyl, 2,2,2-trifluoroethyl or pentafluoroethyl; hydroxy (C 1 -C 6) alkyl can be hydroxymethyl, 1-hydroxymethyl, 2-hydroxyethyl, 1-hydroxypropyl, 2-hydroxypropyl, 3-hydroxypropyl, 1-hydroxybutyl, 4-hydroxybutyl, 1-hydroxypentyl, 5-hydroxypentyl, 1-hydroxyhexyl , or 6-hydroxyhexyl; (C1-C6) alkoxycarbonyl can be methoxycarbonium, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, pentoxycarbonyl, or hexyloxycarbonyl; (C1-C3) aikylthio can be methylthio, ethylthio, propylthio, isopropylthio, butylthio, isobutylthio, pentthylthio, or hexylthio; (C2-C6) alkanoyloxy may be acetoxy, propanoyloxy, butanoyloxy, isobutanoyloxy, pentanoyloxy, or hexanoyloxy; aryl can be phenyl, indenyl, or naphthyl; and heteroaryl may be furyl, imidazolyl, triazolyl, triazinyl, oxazoyl, isoxazoyl, thiazolyl, isothiazolyl, pyrazolyl, pyrrolyl, pyrazinyl, tetrazolyl, pyridyl, (or its N-oxide), thienyl, pyrimidinyl (or its N-oxide), indolyl , isoquinolyl (or its N-oxide) or quinolyl (or its N-oxide). A specific value for R-i is hydrogen, halo, aryl or heteroaryl; wherein any aryl or heteroaryl may be optionally substituted by 1, 2, or 3 substituents independently selected from the group consisting of (C1-C6) alkyl, (C3-C6) cycloalkio, (d-C6) alkoxy, nitro, hydroxy, halo (C1-C6) alkyl, trifluoromethoxy and halo. A specific value for R 2 is hydrogen, halo, aryl, or heteroaryl; wherein any aryl or heteroaryl may be optionally substituted by 1, 2, or 3 substituents independently selected from the group consisting of (C? -C6) alkyl, (C3-C6) cycloalkyl, (C1-C6) alkoxy, nitro, hydroxy, halo (C? -C6) alkyl, trifluoromethoxy, (C3-C6) cycloalkyl (C1-C6) alkyl, (C1-C6) alkanoyl, hydroxy (C? -C6) alkyl, (C1-C6) alkoxycarbonyl, ( C -C6) alkylthio, (C2-C6) alkanoyloxy and halo. Specifically, Ri and R2 taken together can be methylenedioxy. Specifically, Ri and R2 taken together can be benzo, which benzo can be optionally substituted by 1, 2 or 3 substituents independently selected from the group consisting of (C1-C6) alkoxy, (C3-C6) cycloalkyl, (C1-C6) ) alkoxy, nitro, hydroxy, halo (C? -C6) alkyl, trifluoromethoxy, (C3-C6) cycloalkyl (d-C6) alkylo, (C1-C3) alkanoyl, hydroxy (C1-C6) alkyl, (d ~ C6) alkoxycarbonyl, (C1-C6) alkylthio, (C2-C6) alkanoyloxy, and halo. A specific value for R3 is hydrogen. Another specific value for R3 is (C1-C6) alkoxy, nitro, hydroxy, halo (d-C6) alkyl, trifluoromethoxy, (d-C6) alkanoyl, hydroxy (C1-C6) alkyl, (d-C6) alkoxycarbonyl, ( d-C6) alkylthio, (C2-C6) alkanoyloxy or halo. Specifically, R4 and R5 taken together can be -N (H) -N = N-, -N (H) -N (H) -CH2-, -N (H) -N (H) -CH2-CH2-, -N (H) -CH2-N (H) -, -N (H) -CH = CH-, -N (H) -CH2-CH2-, -N (H) -CH2-CH2-CH2-, - N (H) -CH2-CH2-CH2-CH2-, -N (H) -CH2-CH2-N (H), -N (H) -CH2-CH2-O-, -N (H) -CH2- CH2-S-, -N (H) -CH2-CH2-CH2-N (H) -, -N (H) -CH2-CH2-CH2-O-, -N (H) -CH2-CH2-CH2- S-, -N (H) -CH2-CH2-N (H) -CH2-, -N (H) -CH2-CH2-O-CH2-, -N (H) -CH2-CH2-S-CH2- , -N (H) -C - (= O) -C (= O) -CH2, -N (H) -C (= O) -C (= O) -N (H) -, -N (H ) -C (= O) -C (= O) -O-, -N (H) -C (= O) -C (= O) -S-, -N (H) -C (= O) - CH2-CH2-, -N (H) -CH2-N (H) -C (= O) -, -CH2-S-CH2-N (H) -, -CH2-N (H) -CH2- S- , -CH2-N (H) -CH2-, -CH2-CH2-N (H) -CH2-, CH2-CH2-CH2-N (H) -CH2-, - CH2-N (H) -CH2-CH2 -O-, or -CH2-N (H) -CH2-CH2-S-. More specifically, R4 and R5 taken together can be -N (H) -N = N-, -N (H) -CH2-N (H) -, -N (H) -CH = CH-, -N (H ) -CH2-CH2-, -N (H) -CH2-CH2-CH2-, -N (H) -CH2-CH2-CH2-CH2-, -N (H) -CH2-CH2- N (H), -N (H) -CH2-CH2-O-, -N (H) -CH2-CH2-S-, -N (H) -CH2-CH2-CH2-N (H) -, -N (H) - CH2-CH2-CH2-O-, -N (H) -CH2-CH2-CH2-S-, or -N (H) -C (= O) -C (= O) -N (H) -. Preferably, R4 and R5 taken together are -N (H) -N = N-, -N (H) -C (= O) -C (= O) -N (H) -, -N (H) -CH = CH-, -N (H) -CH2-CH2-, -N (H) -CH2-CH2-CH2-, or -N (H) -CH2-CH2-N (H) -. More preferably, R4 and R5 taken together are -N (H) -N = N- or -N (H) -C (= O) -C (= O) - N (H) -, -N (H) -C (= O) -C (= O) -O-, -N (H) -C (= O) -C (= O) -S-, -N (H) -C (= O) -C (= O) -N (H) -. A preferred group of compounds of the formula I are the compounds wherein R-y and R 2 are not both hydrogen. Another preferred group of compounds of the formula I are the compounds wherein Ri and R2 are each independently halo (eg, bromine). A preferred compound of the formula I is a compound of the formula I: wherein Ri-Rs have any of the values defined herein for a compound of the formula I. The processes for preparing the compounds of the formula I are illustrated by the following procedures in which the meanings of the generic radicals are as previously determined unless otherwise qualified. A compound of the formula I wherein R 4 and R 5 taken together are -N (H) -N = N- can be prepared from a corresponding intermediate of the formula I I by treatment with NaNO2 under acidic conditions. The conditions suitable for carrying out such a transformation are described in Example 1. A compound of the formula I wherein R and R5 taken together are -N (H) -C (= O) -C (= O) -N (H) can be prepared from a corresponding compound of the formula II by treatment with oxalic acid under acidic conditions. Suitable conditions for carrying out such a transformation are described in Example 2. A useful intermediary for preparing a compound of formula I is an intermediate of formula II: In cases where the compounds are sufficiently basic or acidic to form salts of stable non-toxic acid or base, administration of the compounds as salts may be appropriate. Examples of pharmaceutically acceptable salts are organic acid addition salts formed with acids which form an acceptable physiological anion, for example, tosylate, methanesulfonate, acetate, citrate, malonate, tartrate, succinate, benzoate, ascorbate, a-ketoglutarate and a- glycerophosphate. Suitable organic salts can also be formed, which include hydrochloride, sulfate, nitrate, bicarbonate and carbonate salts. The pharmaceutically acceptable salts can be obtained using standard procedures well known in the art, for example, by reacting a sufficiently basic compound such as an amine with a suitable acid producing an acceptable physiological anion. Alkali metal salts (eg, sodium, potassium or lithium) or alkaline earth metal (eg, calcium) can also be made from carboxylic acids. The compounds of formula I can be formulated as pharmaceutical compositions and administered to a mammalian host, such as a human patient in a variety of forms adapted to the chosen route of administration, i.e., orally or parenterally, by intravenous, intramuscular, topical routes or subcutaneous. Accordingly, the present compounds can be administered systemically, for example, orally, in combination with a pharmaceutically acceptable carrier such as an inert diluent or an edible assimilable carrier. They can be included in hard or soft core gelatin capsules, can be compressed into tablets, or can be incorporated directly with the patient's diet meal. For oral therapeutic administration, the active compound can be combined with one or more excipients and used in the form of ingestible tablets, buccal tablets, troches, capsules, elixirs, suspensions, syrups, wafers, and the like. Such compositions and preparations should contain at least 0. 1% of the active compound. The percentage of the compositions and preparations can, of course, be varied and conveniently between about 2 to about 60% of the weight of a given unit dosage form can be conveniently found. The amount of the active compound in such therapeutic compositions is such that an effective dose level will be obtained. The tablets, troches, pills, capsules and the like may also contain the following: binders such as gum tragacanth, acacia, corn starch or gelatin; excipients such as dicalcium phosphate; a disintegrating agent such as corn starch, potato starch, alginic acid and the like; a lubricant such as magnesium stearate; and a sweetening agent such as sucrose can be added, fructose, lactose, or aspartame or a flavoring agent such as peppermint, wintergreen oil, or cherry flavoring. When the unit dose form is a capsule, it may contain, in addition to the materials of the type mentioned above, a liquid carrier, such as a vegetable oil or a polyethylene glycol. Various other materials can be found as coatings or to otherwise modify the physical form of the solid unit dosage form. For example, tablets, pills, or capsules can be covered with gelatin, wax, shellac or sugar and the like. A syrup or elixir may contain the active compound, sucrose or fructose as a sweetening agent, methyl and propylparabens as preservatives, a dye and flavoring such as a cherry or orange flavor. Of course, any material used in preparing any form of dosage unit must be pharmaceutically acceptable and substantially non-toxic in the amounts employed. In addition, the active compound can be incorporated into preparations and sustained release devices. The active compound can also be administered intravenously p intraperitoneally by infusion or injection. Solutions of the active compound or its salts can be prepared in water, optionally mixed with a non-toxic surfactant, dispersions in glycerol, liquid polyethylene glycols, triacetin and mixtures thereof and in oils can also be prepared. Under ordinary conditions of storage and use, these preparations contain a preservative to prevent the growth of microorganisms. The pharmaceutical dosage forms suitable for injection or infusion may include sterile aqueous solutions or dispersions or sterile powders comprising the active ingredient which are adapted for the extemporaneous preparation of sterile injectable or infusible solutions or dispersions, optionally encapsulated in liposomes. In all cases, the ultimate dosage form must be sterile, fluid and stable under the conditions of manufacture and storage. The liquid carrier may be a solvent or liquid dispersion medium comprising, for example, water, ethanol, a polyol (eg, glycerol, propylene glycol, liquid polyethylene glycols, and the like), vegetable oils, esters of non-toxic glyceryl and suitable mixtures thereof. The proper fluidity can be maintained, for example, by the formation of liposomes, by the maintenance of the required particle size in the case of dispersions or by the use of surfactants. The prevention of the action of microorganisms can be carried out by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, sorbic acid, thymrosal and the like. In many cases, it will be preferable to include isotonic agents, for example, sugars, compensators or sodium chloride. Prolonged absorption of the injectable compositions can be carried out by the use in the compositions of agents delaying absorption, for example, aluminum monostearate and gelatin. Sterile injectable solutions are prepared by incorporating the active compound in the required amount in the appropriate solvent with several of the other ingredients listed above, as required, followed by filter sterilization. In the case of sterile powders for the preparation of sterile injectable solutions, the preferred preparation methods are the vacuum drying and freeze drying techniques, which produce a powder of the active ingredient plus any additional desired ingredients present in the sterile filtered solutions. previously. For topical administration, the present compounds can be applied in pure form, that is, when they are liquid. However, it will generally be desirable to administer them to the skin as compositions or formulations, in combination with a dermatologically acceptable vehicle, which can be a solid or liquid. Useful solid carriers include finely divided solids such as talc, clay, microcrystalline cellulose, silica, alumina and the like. Useful liquid carriers include water, alcohols or glycols or water-alcohol / glycol mixtures, in which the present compounds can be dissolved or dispersed at effective levels, optionally with the aid of non-toxic surfactants. Adjuvants such as fragrances and additional antimicrobial agents can be added to optimize properties for a particular use. The resulting liquid compositions can be applied from absorbent towels, used to impregnate strips and other garments, or sprayed onto the affected area using pump-type or aerosol-type sprays. Thickeners such as synthetic polymers, fatty acids, fatty acid salts and esters, fatty alcohols, modified celluloses or modified mineral materials can also be used with liquid carriers from pastes, gels, ointments, spreadable soaps, and the like, for the application directly to the user's skin. Examples of useful dermatological compositions which can be used to deliver the compounds of formula I to the skin are known in the art; for example, see Jacquet et al., (U.S. Patent No. 4,608,392), Geria (U.S. Patent No. 4, 992,478), Smith et al., (U.S. Patent No. 4, 559, 1 57 ) and Wortzman (U.S. Patent No. 4,820,508). Useful doses of the compounds of the formula I can be determined by comparing their activity in vitro, and in vivo in animal models. Methods for extrapolation of effective doses in mice, and other animals, to humans are known in the art; for example, see U.S. Patent No. 4, 938, 949. Generally, the concentration of the compound (s) of the formula I in a liquid composition, such as a lotion, will be - from about 0.1-25%. in weight, preferably from about 0.5-10% by weight. The concentration in a semi-solid or solid composition such as a gel or powder will be about 0.1-5% by weight, preferably about 0.5-2.5% by weight. The amount of the compound, or a salt or active derivative thereof, required for use in treatment, will not only vary with the particular salt selected but also with the route of administration, the nature of the condition being treated and the age and patient's condition and will ultimately be at the discretion of the attending physician or clinician. However, generally, a suitable dose will be in the range of from about 0.5 to about 100 mg / kg, for example, from about 10 to 75 mg / kg of body weight per day, such as 3 to 50 mg per kilogram of body weight of the container per day, preferably in the range of 6 to 90 mg / kg / day, more preferably in the range of 1-5 to 60 mg / kg / day. The compound is conveniently administered in the form of unit doses; for example, containing 5 to 1000 mg, conveniently 1 to 750 mg, more conveniently, 50 to 1000 mg of active ingredient per unit dosage form. Ideally, the active ingredient should be admixed to achieve peak pasmate concentrations of the active compound of from about 0.5 to about 75 μM, preferably about 1 to 50 μM, more preferably, about 2 to 30 μM. This can be achieved, for example, by intravenous injection of a 0.05 to 5% solution of the active ingredient, optionally administered in saline, or orally as a bolus containing about 1-100 mg of the active ingredient. Desirable blood levels can be maintained by continuous infusion to provide approximately 0.01 -5.0 mg / kg / hr or by intermittent infusions containing approximately 0.4-15 mg / kg of the active ingredient (s). The desired dose may conveniently be presented in a single dose or as divided doses administered at appropriate intervals, for example, as two or three, four or more sub-doses per day. The sub-dose itself may be further divided, for example, into a number of discrete administrations loosely spaced; such as multiple inhalations from an insufflator or by applying a plurality of drops to the eye. The ability of a compound of the invention to perform DNA segmenting mediated by topoisomerase I can be determined using pharmacological models that are well known in the art, for example, using a model similar to Test A described below. Test A Topoisomerase I Cleavage Assay Representative compounds of the invention were evaluated in a cleavage assay using recombinant topoisomerases I. This assay was performed as described by B. Gatto et al., Cancer Res., 1996, 56, 2795-2800. Human topoisomerase I was isolated as a recombinant fusion protein using a T7 expression system. Plasmid YEpG was purified by the alkali lysis method followed by deproteinization of phenol and isopycnic centrifugation of CsCI / ethidium as described by Maniatis, T.; Fritsch, E. F.; Sambrook, J Molecular Cloning, a Laboratory Manual; Cold Spring Harbor Laboratory: Cold Spring Harbor, NY 1 982; p. 149-1 85. The final labeling of the plasmid was performed by digestion with a restriction enzyme followed by a final fill with Klenow polymerase as previously described by Liu, L. F.; Rowe, T.C. , Yang, L; Tewey, K.M.; Chen, G. L. "Cleavage of DNA by mammalian topoisomerase I I", J. Biol. Chem., 1983, 258, 1 5365. The IC5o values were calculated after 4 days of continuous exposure to the drug. The topoisomerase I cleavage values were reported as REC, Relative Effective Concentration (ie, concentrations relative to the compounds, 5, whose value is arbitrarily assumed as 1) that it is possible to produce the same segmentation in the plasmid DNA in the presence of topoisomerase I human. The cytotoxic effects of a compound of the invention can be determined using pharmacological models which are well known in the art, for example, using a model similar to Test B described below.

Test B Cytotoxicity test Cytotoxicity was determined using the MTT-microtiter plate tetrazolium cytotoxicity (MTA) assay (See Chen AY et al., Cancer Res., 1993, 53, 1332; Mosmann, TJ, J. Immunol. Methods, 1983, 65, 55, and Carm ichael, J., et al., Cancer Res. 1987, 47, 936). The human lymphoblast RPMI 8402 and its camptothecin-resistant variable cell line, CPT-K5 were provided by Dr. Toshiwo Andoh (Aichi Cancer Center Research Institute, Nagoya, Japan) (see Andoh, T.; Okada, K. " Drug resistance mechanisms of topoisomerase I drugs ", Adv. In Pharmacology 1994, 29B, 93). The cytotoxicity assay was performed using 96-well microtiter plates. Cells were grown in suspension at 37 ° C in 5% CO2 and maintained by regular passage in RPMI medium supplemented with heat-deactivated fetal bovine serum at 10%, L-glutamine (2mM), penicillin (100 U / mL), and streptomycin (0.1 mg / mL). For the determination of IC5o, the cells were exposed continuously with varying drug concentrations and MTT assays were performed at the end of the fourth day. The data derived from Test A and Test B are shown in Table 1 for the representative compounds of the invention.

Table 1 . Pharmacological Activity of the Compounds of the Invention.

Compound Segmentation Cytotoxicity IC5o (μM) of DNA mediated RPM CPT-K5 The compounds of the formula I are powerful topoisomerase I poisons. Additionally, the compounds of the formula I exhibit cytotoxic activity against the RPM I 8402 cancer cells and camptothecin-resistant CPT-K5 cells. Accordingly, the compounds of the formula I are useful as cytotoxic agents, for the treatment of cancers, and in particular, solid mammary tumors or malignancies. The compounds of the invention are also useful as pharmacological tools for the in vitro and in vivo study of topoisomerase function and activity. The comparison of the data for compounds 2 and 3 with the data for compound 4 suggests that the topoisomerase poisoning activity and the cytotoxic activity improve when R4 and R5 taken together are a chain comprising an H-binding functionality ( example, NH). Accordingly, the invention provides compounds of the formula I wherein R and R5 taken together are a chain comprising at least one N-H group. As used herein, the term "solid mammalian tumors" includes cancers of the head and neck, lung, mesothelioma, mediastinum, esophagus, stomach, pancreas, hepatobiliary system, small intestine, colon, rectum, anus, kidney, ureter, bladder. , prostate, urethra, penis, testes, gynecological organs, ovaries, chest, endocrine system, central nervous system of skin; soft tissue and bone sarcomas, and melanoma of cutaneous and infra-ocular origin. The term "hermatological malignancies" includes childhood leukemia and lymphomas, Hodgkin's disease, lymphomas of lymphocytic and cutaneous origin, acute and chronic leukemia, plasma cell neoplasm and cancers associated with AIDS. The preferred mammal species for treatment are humans and domesticated animals. The invention will now be illustrated by the following non-limiting examples, wherein unless stated otherwise: the melting points were determined with a Thomas-Hoover Unimelt capillary melting point apparatus; column chromatography refers to flash chromatography conducted on SiliTech 32-63 μm, (ICN Biomedicals, Eschwegge, Ale.) using the solvent systems indicated; the infrared spectral data (IR) were obtained in a Perkin-Elmer 1600 Fourier transform spectrophotometer and were reported in cm "1, and proton (1 H NMR) and carbon (13C NMR) nuclear magnetic resonances were recorded in a Fourier Transform Spectrometer Varied Gemini-200, NMR spectra (200 MHZ 1H and 50 MHZ 13C) were recorded in the indicated deuterated solvent with reported chemical changes in descending d units from tetramethylsilane (TMS); the coupling constants are reported in hertz (Hz); mass spectra were obtained from the Washington University Resource for Biomedical and Bio-organic Mass Spectometry within the Department of Chemistry at the University of Washington, St. Louis, MO; and combustion analyzes were performed by Atlantic Microlabs, Inc., Norcross, GA, and were within ± 0.4% of the theoretical value.

EXAMPLES Example 1. 5-Phenyl-2 '- (benzotriazol-5-yl) -bibenzimidazole (2). 5-Phenyl-2- [2 '- (3,4-aminophenyl) benzimidazole was dissolved 'l] benzimidazole (1), (58 mg, 0.14 mmol) in 0.1N HCl. This solution was placed in an ice bath and while maintaining a reaction temperature below 10 ° C, NaNO2 (10.2 mg) was added in 5 mL of water dropwise. The reaction mixture was stirred for 15 minutes, neutralized with 0.1N KOH, extracted with ethyl acetate, and the resulting material was purified by chromatography, with 10% methanol: ethyl acetate as the eluent to deliver the compound main as a dark brown solid which had to be stored immediately in an amber bottle due to its sensitivity to light; 42 mg (71%); ? mp > 28 ° C; IR (KBr) 3385, 3128, 3056, 1626, 1431, 1287; UV (MeOH) 340, 245, 230 nm (log e = 4.59, 4.59, 4.59); 1H NMR (DMSO- 6 + 3 drops of CF3COOH) d 7.47-7.61 (m, 3H), 7.79-8.07 (m, 6H), 8.15-8.19 (m, 2H), 8.40 (d, 1H, ¿= 9.0) , 8.63 (s, 1H), 8.67 (s, 1H); 13 C NMR (D SO-of β + 3 drops of CF 3 COOH) d 107.4, 111.7, 114.1, 114.6, 115.9, 116.3, 117.8, 122.3, 123.2, 1 25.5, 125.6, 126.6, 1 28.0, 1 29.2, 129.5, 1 31. 9, 1 33.2, 1 34.7, 138.7, 139.8, 141.4, 147.1, 150.7, 154.3; HRMS (FAB) caled, for C 26 H 17 N 7 (MH +) 428.1624, found 428.1622. The intermediate 5-Phenyl-2- [2 '- (3,4-aminophenyl) benzimidazol-5'yl] benzimizadol was prepared as follows, a. 5-Phenyl-2- [2 '- (3,4-aminophenyl) benzimidazol-5'yl] benzamide A solution of 5-phenyl-2- [2' - (3,4-dinitrophenyl) benzimidazol-5'yl] benzimizadol (75 mg, 0.16 mmol) in ethyl acetate (50 mL) was reduced by hydrogenation in 10% Pd / C (15 mg) for 90 minutes. The resulting solution was passed through a pad of Celite and ethyl acetate was extracted to deliver diamine 1, which was used without further purification. 5-Phenyl-2- [2 '- (3,4-dinitrophenyl) -5-yl) benzimidazole-5'-1-benzimidazole can be prepared as described by JS Kim et al., Med. Chem., 1997, 40, 281 8-2824.

Example 2. 5-Phenyl-2 '- (quinoxaline-6-yl) -bibenzimidazole (3). Diamine 1 (55 mg, 0.1 3 mmol) was dissolved in water (4 mL) and heated to 70 ° C. It was dissolved in Glioxal 2NaHSO3 (50 mg, 0.13 mmol) in hot water (80 ° C, 3 μL) and slowly added to the diamine (as described by Jones, RG .; McLaughlin, KC 2,3-Pyrazine-dicarboxylic acid). Org Synth, 1950, 30, 86). After 15 minutes, the reaction mixture was cooled to room temperature and Na2CO3 was added. extraction with ether followed by chromatographic separation with 10% ethyl methanokacetate as the eluent gave the main compound as a yellow solid; 38 mg (67%); mp 235 ° C; IR (KBr) 3385, 3169, 1624, 1554, 1431, 1297; UV (MeOH) 360, 255, 220 nm (log e = 4.52, 4.65, 4.59); 1 H NMR (DMSO-c / 6 + 3 drops of CF 3 COOH) d 7.46-7.61 (m, 3H), 7.80 (d, 2H, J = 8.0); 7.89-8.26 (m, 5H), 8.36 (d, 1H, = 9.0), 8.69-8.78 (m, 2H), 9.04-9.10 (m, 3H); 13C NMR (DMSO-cf6 + 3 drops of CF3COOH) d 111.7, 114.6, 116.5, 116.6, 117.9, 123.5, 123.9, 125.6, 127.5, 128.1, 128.2, 128.3, 128.6, 130.6, 131.6, 132.9, 138.9, 139.1, 139.7 , 142.5, 143.7, 143.8, 147.3, 150.5, 153.1; HRMS (FAB) caled, for C28H19N6 (MH +) 439.1671, found 439.1677.

Example 3. 5-Phenyl-2 '- (quinoxalinadione-6-yl) -bibenzimidazole (4). Diamine 1 (40 mg, 0.096 mmol) and oxalic acid (20 mg, 0.22 mmol) were refluxed in 4N HCl overnight (as described by Ohmori, J. et al., J. Med. Chem. 1996, 39 , 1331-1338). After remaining at room temperature, the main compound was precipitated from the reaction mixture as a brownish solid; 15 mg (33%); mp > 280 ° C; IR (KBr) 3339, 3217, 2845, 1623, 1578, 1506, 1469, 1272; 1H NMR (DMSO-d6) d 6.96 (d, 1H, = 9.0), 7.41-7.60 (m, 4H), 7.77-8.00 (m, 7H), 8.32 (d, 1H, = 9.0), 8.57 (s, 1 HOUR); 13C NMR (DMSO-de + 3 drops of CF3COOH) d 106.5, 107.4, 111.7, 114.1, 114.7, 115.2, 115.2, 116.7, 119.5, 122.3, 124.7, 125.7, 127.5, 128.2, 129.4, 131.9, 133.2, 138.8, 139.7, 139.8 149.7, 152.7, 158.2; HRMS (FAB) caled, for C28H19N6O2 (MH +) 471.1569, found 471.1584.EXAMPLE 4 The following illustrates the representative pharmaceutical dosage forms, which contain a compound of the formula I ('compound X'), for therapeutic or prophylactic use in humans. (i) Tablet 1 mq / tablet 'Compound X' 1 00.0 Lactose 77.5 Providone 1 5.0 Croscarmellose sodium 12.0 Microcrystalline cellulose 92.5 Magnesium stearate 3.0 300.0 (ii) Tablet 2 mg / tablet 'Compound X' 20.0 Microcrystalline cellulose 41 0.0 Fécula 50.0 Sodium starch glycolate 15.0 Magnesium stearate 5.0 500.0 (iii) Capsule mg / capsule 'Compound X' 1 0.0 Colloidal silicon dioxide 1.5 Lactose 465.5 Pregelatinized starch 120.0 Magnesium stearate 3.0 600.0 (iy) Invention 1 (1 mg / ml) mg / ml 'Compound X' (free acid form) 1 .0 Dibasic sodium phosphate 12.0 Monobasic sodium phosphate 0.7 Sodium chloride 4.5 1 .0 N sodium hydroxide solution (pH adjustment at 7.0-7.5) q .s. Ag ua for injection q.s. and 1 m L (v) I nvection 2 (10 mg / ml) mg / m l 'Compound X' (free acid form) 1 0.0 Sodium phosphate monobasic 0.3 Dibasic sodium phosphate 1 .1 Polyethylene glycol 400 200.0 01 N sodium hydroxide solution (pH setting at 7.0-7.5) q .s. Water for injection q .s. and 1 mL (vi) Aerosol mg / can 'Compound X' 20.0 Oleic acid 1 0.0 Trichloromonof luoromethane 5, 000.0 Dichlorodifluoro meta no 1 0,000.0 Dichlorotetrafluoroethane 5,000.0 The formulations cited above can be obtained by conventional procedures well known in the pharmaceutical art. The invention has been described with reference to various specific and preferred modalities and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope of the invention.

Claims (22)

1. CLAIMS What is claimed is: 1. A compound of the formula I: wherein Ri and R2 are each independently hydrogen, (C, -Cs) alkyl, (C3-C6) cycloalkyl, (C1-C6) alkoxy, nitro, hydroxy, halo (d-C6) alkyl, trifluoromethoxy, halo, ( C3-C6) cycloalkyl (d-C6) alkyl, (C, -C6) alkanoyl, hydroxy (d-C6) alkyl, (C1-C6) alkoxycarbonyl, (d-C6) alkylthio, (C2-C6) alkanoyloxy, aryl or heteroaryl; or R, and R 2 taken together are methylenedioxy; or R, and R2 taken together are benzo; wherein any aryl, heteroaryl or benzo may be optionally substituted by 1, 2 or 3 substituents independently selected from the group consisting of (d -C6) alkyl, (C3-C6) cycloalkyl, (d-C6) alkoxy, nitro, hydroxy, halo (C1-C6) alkyl, trifluoromethoxy, (C3-C6) cycloalkyl (C1-C6) alkyl, (d-C6) alkanoyl, hydroxy (C6-C6) alkyl, (d-C6) alkoxycarbonyl, (C1-C6) aicytthio, (C2-C6) alkanoyloxy and halo; R3 is hydrogen, (C1-C6) alkyl, (C3-C6) cycloalkyl, (d- C6) alkoxy, nitro, hydroxy, halo (d-C6) alkyl, trifluoromethoxy, (C3-C6) cycloalkyl (C1-6) C6) alkyl, (C 1 -C 6) alkanoyl, hydroxy (C 1 -C 6) aikyl, (C -, - C 6) alkoxycarbonyl, (C 1 -C 6) aicytthio, (C 2 -C 6) alkanoyloxy, or halo; and R4 and R5 taken together are a saturated chain 0 unsaturated consisting of 3, 4 or 5 members comprising members selected from the group consisting of non-peroxide oxygen, sulfur, N (X), and carbon, optionally substituted by oxo; wherein each X is independently absent or is H, O, (C1-C) alkyl, phenyl or benzyl; and where at least one (for example, 1 or 2) of said chain members is a N-H g rupe; or a pharmaceutically acceptable salt thereof; R and R5 provided, taken together are not -N (H) -C (H) = N-. The compound according to claim 1, characterized in that R ^ is hydrogen, halo, aryl or heteroaryl, wherein any aryl or heteroaryl can be optionally substituted by 1, 2 or 3 substituents independently selected from the group consisting of (d- C6) alkyl, (C3-C6) cycloalkyl, (Cr C6) alkoxy, nitro, hydroxy, halo (C1-C6) alkyl, trifluoromethoxy and halo. 3. The compound according to claim 1, characterized in that R2 is hydrogen, halo, aryl or heteroaryl; wherein any aryl or heteroaryl may be optionally substituted by 1, 2 or 3 substituents independently selected from the group consisting of (C1-C6) alkyl, (C3-C6) cycloalkyl, (d- C6) alkoxy, nitro, hydroxy , halo (C1-C6) alkyl, trifluoromethoxy, (C3-C6) cycloalkyl (C1-C6) alkyl, (C1-C6) alkanoyl, hydrox-d-C-Jalkyl, (d-C6) alkoxycarbonyl, (C1-C6) alkylthio, (C2-C6) alkanoyloxy and halo. 4. The compound according to claim 1, characterized in that R- and R2 taken together are methylodoxy. 5. The compound according to claim 1, characterized in that R ^ and R2 taken together are benzo, which benzo can be optionally substituted by 1, 2 or 3 substituents independently selected from the group consisting of (C1-C6) alkoxy, (C3) -C6) cycloalkyl, (d-C6) alkoxy, nitro, hydroxy, halo (d-C6) alkyl, trifluoromethoxy, (C3-C6) cycloalkyl (d-C6) alkyl, (C1-C6) alkanoyl, hydroxy (C1-C6) alkyl, (dC6) alkoxycarbonyl, (C1-C6) alkylthio, (C2-C6) alkanoyloxy, and halo. 6. The compound according to claim 1, characterized in that R3 is hydrogen. 7. The compound according to claim 1, characterized in that R3 is (d-C6) alkoxy, nitro, hydroxy, halo (d-C6) alkyl, trifluoromethoxy, (d-C6) alkanoyl, hydroxy (d-C6) alkylo , (Cr C6) alkoxycarbonyl, (C 1 -C 6) alkylthio, (C 2 -C 6) alkanoyloxy or halo. 8. The compound according to claim 1, characterized in that R and R5 taken together are -N (H) -N = N-, -N (H) -N (H) -CH2-, -N (H) -N ( H) -CH2-CH2-, -N (H) -CH2-N (H) -, -N (H) -CH = CH-, -N (H) -CH2-CH2-, -N (H) - CH2-CH2-CH2-, -N (H) -CH2-CH2-CH2-CH2-, -N (H) -CH2-CH2-N (H), -N (H) -CH2-CH2-O-, -N (H) -CH2-CH2-S-, -N (H) -CH2-CH2-CH2-N (H) -, -N (H) -CH2-CH2-CH2-O-, -N (H ) -CH2-CH2-CH2- S-, -N (H) -CH2-CH2-N (H) -CH2-, -N (H) -CH2-CH2-O-CH2-, -N (H) -CH2-CH2-S-CH2-, - N (H) -C - (= O) -C (= O) -CH2, -N (H) -C (= O) -C (= O) -N (H) -, -N (H) - C (= O) -C (= O) -O-, -N (H) -C (= O) -C (= O) -S-, -N (H) -C (= O) -CH2- CH2-, -N (H) -CH2-N (H) -C (= O) -, -CH2-S-CH2-N (H) -, -CH2-N (H) -CH2-S-, - CH2-N (H) -CH2-, -CH2-CH2-N (H) -CH2-, CH2-CH2-CH2-N (H) -CH2-, -CH2-N (H) -CH2-CH2-O -, or -CH2-N (H) -CH2-CH2-S-. 9. The compound according to claim 1, characterized in that R4 and R5 taken together are -N (H) -N = N-, -N (H) -CH2-N (H) -, -N (H) -CH = CH-, -N (H) -CH2-CH2-, -N (H) -CH2-CH2-CH2-, -N (H) -CH2-CH2-CH2-CH2-, -N (H) -CH2- CH2-N (H), -N (H) -CH2-CH2-O-, -N (H) -CH2-CH2-S-, -N (H) -CH2-CH2-CH2-N (H) - , -N (H) -CH2-CH2-CH2-O-, -N (H) -CH2-CH2-CH2-S-, or -N (H) -C (= O) -C (= O) - N (H) -. The compound according to claim 1, characterized in that R4 and R5 taken together are -N (H) -N = N-, -N (H) -C (= O) -C (= O) -N (H ) -, -N (H) -CH = CH-, -N (H) -CH2-CH2-, -N (H) -CH2-CH2-CH2-, or -N (H) -CH2-CH2-N (H) -. eleven . The compound according to claim 1, characterized in that R4 and R5 taken together are -N (H) -N = N-, or -N (H) -C (= O) -C (= O) -N (H) - . The compound according to claim 1, characterized in that R and R2 are not both hydrogen. The compound according to claim 1, characterized in that Ri and R2 are each independently halo. The compound according to claim 1, characterized in that R-i and R2 are each bromine. 15. A pharmaceutical composition comprising a compound of any of claims 1-14, in combination with a pharmaceutically acceptable diluent or carrier. 1 6. A therapeutic method comprising inhibiting cancer cells by administering to a mammal in need of such therapy, an amount of a compound of claim 1, effective to inhibit said cancer cells. 17. A method comprising inhibiting cancer cells by contacting said cancer cells with an effective amount of a compound of claim 1. 18. A compound of any of claims 1-14 for use in medical therapy. 9. The compound of claim 18, characterized in that the medical therapy is to treat cancer. 20. The compound of claim 19, characterized in that the cancer is a solid tumor. twenty-one . The use of a compound of any of claims 1-14 for the manufacture of a medicament useful for the treatment of cancer. 22. The use of claim 21 characterized in that the cancer is a solid tumor.