WO2009124184A2 - Methods of activating rnase l - Google Patents

Abstract

A method of activating RNase L in a subject in need thereof comprises administering to the subject an effective amount of a compound represented in Structural Formula (I) or a pharmaceutically acceptable salt thereof. The activation of RNase L treats a viral infection, cancer or restenosis.

Description

METHODS OF ACTIVATING RNASE L

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/123,005, filed on April 4, 2008, the entire teachings of which are incorporated herein by reference.

GOVERNMENT SUPPORT

The invention was supported, in whole or in part, by a grant NIAID/NIH U54-A1057160. The Government has certain rights in the invention.

BACKGROUND OF Tl IE INVENTION

Antiviral agents that stimulate host immunity have inherent advantages over those that block viral proteins. While drugs that target specific viral proteins may be efficacious for a specific virus or type of virus, they generally lack broad- spectrum antiviral activity and often lead to viral escape mutants. By contrast, antiviral strategies involving the host innate immune system are expected to provide a wider antiviral effect against unrelated types of viruses. Type I interferons (IFNs) are the principal antiviral cytokines produced during the innate immune response to a wide range of different types of viral infections². Although IFNs are used clinically against hepatitis C virus (in combination with ribavirin) and a few other human viral pathogens, the clinical uses of IFNs as antiviral agents are very limited because most if not all viruses have acquired or evolved mechanisms for evading IFNs. Furthermore, significant adverse effects of IFNs often limit their clinical applications. While almost any step in the IFN antiviral response is a potential target for viral virulence genes, the early steps, in particular induction of type I IFN genes and IFN signal transduction through the JAK-STAT pathway, are frequently blocked by viruses³.

The 2-5A/RNase L pathway is a classical innate immunity pathway activated by IFNs and double-stranded RNA (dsRNA), the viral pathogen associated molecular pattern⁴ (see Fig. 1). RNase L is an antiviral enzyme in the interferon (IFN) system. When stimulated by dsRNA, IFN-inducible 2',5'-oligoadenylate synthetases produce a series of short 5'-phosphorylated, 2',5'-linked oligoadenylates collectively referred to as 2-5 A [p_x5'A(2'p5'A)_n; x = 1-3; n>2] from ATP⁵. Because dsRNA is frequently produced during viral infections, 2-5A often accumulates in IFN-treated and virus-infected cells ^" . The principal species of 2-5 A found in such cells is the trimeric form, p₃A2'p5 A2'p5'A⁶. The only well-established function of 2-5A is activation of RNase L⁹. It is believed that, to activate RNase L, 2-5A must have at least one 5'-phosphoryl group to activate RNase L, and the internucleotide linkages must be 2' to 5' and the nucleotides must by adenylyl residues . RNase L is activated by subnanomolar levels of 2-5 A resulting in the cleavage of single- stranded regions of RNA, preferentially after UU and UA dinucleotides ^{l > 12}. Since many viruses block the IFN system upstream of RNase L, for instance by sequestering dsRNA from 2',5'-oligoadenylate synthetases¹³'¹⁴, direct activation of RNase L is expected to induce an antiviral response. 2-5A, which is an activator of RNase L, however has unfavorable pharmacologic properties. It is rapidly degraded, does not transit cell membranes because of the phosphoryl groups, and leads to apoptosis.

Thus, there is a need for new activators of RNase L for clinical use, for example, for treating a viral infection.

SUMMARY OF THE INVENTION

The present invention generally relates to a method of activating RNase L in a subject in need thereof with a compound represented in Structural Formula (I):

(I), or a pharmaceutically acceptable salt thereof.

Q is -OR², -SR² Or -NR³R⁴.

R¹ and R² are each independently -H, an optionally substituted aliphatic group, an optionally substituted aryl group or an optionally substituted heterocyclic group.

R³ and R⁴ are each independently -H, an optionally substituted aliphatic group, an optionally substituted aryl group or an optionally substituted heterocyclic group, or, R³ and R⁴, taken together with the nitrogen atom to which R³ and R⁴ are attached, form an optionally substituted, non-aromatic, heterocyclic ring.

Each of rings A and B is independently and optionally substituted.

In one embodiment, the present invention is directed to a method for activating RNase L in a subject in need thereof, comprising administering to the subject an effective amount of a compound represented by Structural Formula (1) or a pharmaceutically acceptable salt thereof, wherein the variables of Structural Formula (I) are as described above, provided that when Q is -NH₂, R¹ is then an optionally substituted cyclic alkyl group, an optionally substituted aryl group or an optionally substituted hetrocyclic group.

In one specific embodiment, the activation of RNase L treats a viral infection. In another specific embodiment, the activation of RNase L treats cancer. In yet another specific embodiment, the activation of RNase L treats restenosis.

In another embodiment, the present invention is directed to a method for treating a subject with cancer, restenosis, or a viral infection by one or more viruses selected from the group consisting of encephalomyocarditis virus, vesicular stomatitis, xenotropic virus, Sendai virus, parainfluenza virus, vaccinia virus and xenotropic MLV related virus (XMRV), comprising administering to the subject an effective amount of a compound represented by Structural Formula (I) or a pharmaceutically acceptable salt thereof, wherein the variables of Structural Formula (I) are as described above. Also, use of a compound disclosed herein or a pharmaceutically acceptable salt thereof in therapy for treating a subject with a viral infection, cancer, or restenosis is included in the present invention. - A -

Also included in the present invention is the use of a compound disclosed herein or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for treating a subject with a viral infection, cancer, or restenosis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing showing the OAS/RNase L system, a pathway that functions in antiviral innate immunity.

FIG. 2(a) is a graph showing activation of RNase L by FRET assays with 5 μM (micromole) of compounds A-P and 5 μM (mieromole) of compounds 1 and 2 reported in reference 1 (Thakur, C. et al, Proc. Natl. Acad. Sci, U.S.A. 104, 9585- 9590 (2007)).

FIG. 2(b) is a graph showing dose dependence of Compound J for RNase L activation in FRET assays.

FIG. 2(c) is a graph showing suppression of viral replication by compound J in an RNase L-dependent manner.

FIG. 2(d) is a graph showing the binding data of Compound J to the kinase- endonuclease (KEN) domain of RNase L.

FIG. 3 is a graph showing dose dependences of (2'-5')p3A3 for activation of RNase L in FRET assays. FIG. 4 shows a gel based FRET assay demonstrating RNase L activation by

Compounds J, JR4, JR5 and JR6. The FRET assay was performed as detailed in the methods, with compound alone control (no RNase L). 16μl of from each well was mixed with 4μl of 5X RNA gels loading dye (Ambion) after 15 minutes of incubation, at room temp and loaded on a pre-equilibrated 20% urea denaturing gel and electrophorsed at 200 volt for 2 hour prior to visualize by Molecular Imager FX (Bio Rad). Compound concentration was 0.5μM and that of 2-5A was 3nM. Each experiment was done in triplicate.

FIG. 5 is a graph showing dose dependence of Compound JR4 for RNase L activation in FRET (fluorescence resonance energy transfer) assays. DETAILED DESCRIPTION OF THE INVENTION

The compounds disclosed herein can activate RNase L, As shown in the Examples, a number of compounds activated RNase L. In particular, Compound J had about 7- to 9-fold more active than compounds 1 and 2 of WO 2007/127212 (the entire teachings of which are incorporated herein by reference).

In one embodiment, the present invention relates to a method of treating a viral infection, cancer or restenosis in a subject with a compound disclosed herein, including a compound described in the CLAIMS below.

Specific compounds that can be employed in the invention include:

(Compound E),

(Compound J),

ompound JR4),

(Compound JR5), and

(Compound JR6), and a pharmaceutically acceptable salt thereof.

Other specific compounds that can be employed in the invention include: (Compound A),

(Compound B),

(Compound C),

(Compound D),

(Compound H),

(Compound G),

(Compound F)

(Compound I),

(Compound L),

(Compound M),

(Compound K),

(Compound P),

(Compound N),

(Compound O),

(Compound JRl),

(Compound JR2),

(Compound JR3),

10

(Compound JR7),

(Compound JR8),

(Compound JR9),

(Compound JRlO), and

(Compound JRl 1), and a pharmaceutically acceptable salt thereof. Viral infections which can be treated with the compounds disclosed herein include viruses with single-stranded RNA(s) for their genome. Examples include orthomyxoviruses (e.g. influenza viruses), paramyxoviruses (e.g. respiratory syncytial virus & human parainfluenza virus-3), rhabdoviruses (e.g. rabies virus), togaviruses (e.g. rubella virus and eastern equine encephalitis virus), picornaviruses (e.g. poliovirus & Coxsackieviruses), flaviviruses (e.g. West Nile virus, Dengue virus, and hepatitis C virus), bunyaviruses (e.g. LaCrosse virus, Rift Valley fever virus & Hantavirus), retroviruses (e.g. the gammaretrovirus XMRV and the lentiviruses HIV-I & -2), filoviruses (e.g. Ebolavirus, hemorrhagic fever virus) or hepatitis B virus (a DNA virus with a genomic RNA intermediate).

The compounds disclosed herein can also be used to treat infections from certain DNA viruses, including human papillomavirus, herpes simplex virus- 1 and - 2, cytomegalovirus, and human herpesvirus-8. Additionally, the compounds disclosed herein can also be used to treat infections from certain DNA viruses including Variola virus (smallpox virus), Monkeypox virus, Molluscum contagiosum virus, Epstein-Barr virus, adenovirus, varicella- zoster virus, human herpesvirus 6, human herpesvirus 7, Bl 9 parvovirus, adeno-associated virus, BK virus, and JC virus as well.

In one specific embodiment, the compounds disclosed herein can also be used to treat infections from encephalomyocarditis virus (EMCV), vesicular stomatitis (VSV), xenotropic virus (e.g., xenotropic MuLV-related virus (XMRV), Sendai virus, parainfluenza virus (e.g., human parainfluenza virus-3 (HPIV-3)) and vaccinia virus.

The RNase L activators disclosed herein can also be used to treat cancer. Preclinical studies on RNase L have suggested that it is an important target for cancer therapeutics (Adah SA, Bayly SF, Cramer H, Silverman RH, Torrence PF. (Curr Med Chem. 2001 Aug;8(10): 1189-212). For example, the hereditary prostate cancer 1 (FIPCl) susceptibility locus was recently mapped to the RNase L gene (Carpten J, Nupponen N, Isaacs S, Sood R, Robbins C, Xu J, Faruque M, Moses T, Ewing C, Gillanders E, Hu P, Bujnovszky P, Makalwska I, Baffoe-Bonni A, Faith D, Smith J, Stepah D, Wiley K, Brownstein M, Gildea D, Kelly B, Jenkins R, Hostetter G, Matikainen M, Schleutker J, Klinger K, Conners T, Xiang Y, Wang Z, Demarzo A, Papdopoulos N, Kallioniemi O-P, Burk R, Meyers D, Gronberg H, Meltzer P, Silverman R, Bailey- Wilson J, Walsh P, Isaacs W, Trent J. Nature Genetics 2002, Jan 22). In addition, it has been previously demonstrated that RNase L participates in the anti-cell proliferation activity of IFN (Hassel BA, Zhou A, Sotomayor C, Maran A, Silverman RH. EMBO J. 1993 Aug;12(8):3297-304). 2- 5 A induces through RNase L the degradation of ribosomal RNA (rRNA) and messenger RNA (mRNA), thereby reducing levels of protein synthesis, properties that if applied to aortic smooth muscle cells, could prevent restenosis following angioplasty. Also, transfection of PC3 or DU 145 cells with 2-5 A causes apoptosis (Xiang

Y, Wang Z, Murakami J, Plummer S, Klein EA, Carpten JD, Trent JM, Isaacs WB, Casey G, Silverman RH. Cancer Res. 2003 Oct 15; 63(20):6795-801). Both DU 145 and PC3, cell lines derived from metastatic brain and bone prostate cancer cases respectively, are wild type for RNase L. In addition, 2-5A transfection causes caspase-dependent apoptosis in human ovarian carcinoma cells through a mitochondrial pathway (Rusch L, Zhou A, Silverman RH. J Interferon Cytokine Res. 2000 Dec;20(12): 1091 -100). Furthermore, 2-5 A linked to antisense against telomerase RNA caused apoptosis and anti-tumor activities against DU 145 tumors in nude mice (Kondo Y, Koga S, Komata T, Kondo S. Oncogene. 2000 Apr 27;19(18):2205-l 1). Based on the foregoing, the disclosed activators of RNase L can be used to treat cancers.

Examples of cancers which can be treated with the disclosed RNase L activators include, but are not limited to, human sarcomas and carcinomas, e.g., fibrosarcoma, myxosarcoma, liposarcoma, chondrosarcoma, osteogenic sarcoma, chordoma, angiosarcoma, endotheliosarcoma, lymphangiosarcoma, lymphangioendotheliosarcoma, synovioma, mesothelioma, Ewing's tumor, leiomyosarcoma, rhabdomyosarcoma, colon carcinoma, pancreatic cancer, breast cancer, ovarian cancer, prostate cancer, squamous cell carcinoma, basal cell carcinoma, adenocarcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillary carcinoma, papillary adenocarcinomas, cystadenocarcinoma, medullary carcinoma, bronchogenic carcinoma, renal cell carcinoma, hepatoma, bile duct carcinoma, choriocarcinoma, seminoma, embryonal carcinoma, Wilms' tumor, cervical cancer, testicular tumor, lung carcinoma, small cell lung carcinoma, bladder carcinoma, epithelial carcinoma, glioma, astrocytoma, medulloblastoma, craniopharyngioma, ependymoma, pinealoma, hemangioblastoma, acoustic neuroma, oligodendroglioma, meningioma, melanoma, neuroblastoma and retinoblastoma. The disclosed RNase L activators are commonly used to treat prostate cancer, ovarian cancer, brain cancer or bone cancer,

Restenosis is a condition which can develop in blood vessels which have undergone coronary procedures or peripheral procedures with PTCA balloon catheters (e.g. percutaneous transluminal angioplasty). Restenosis is the development of scar tissue from about three to six months after the procedure and results in narrowing of the blood vessel. Restenosis is caused excessive smooth muscle proliferation. Because the disclosed RNase L activators inhibit smooth muscle proliferation, it is believed that these compounds can be used to inhibit, treat and/or prevent restenosis. It is to be understood that when any compound is referred to herein by name or structure, solvates, hydrates and polymorphs thereof are included.

The compounds disclosed herein may contain one or more chiral center and/or double bond and, therefore, exist as stereoisomers, such as double-bond isomers (i.e., geometric isomers), enantiomers, and/or diastereomers. When compounds of the invention are depicted or named without indicating the stereochemistry, it is to be understood that both stereomerically pure forms (e.g., geometrically pure, enantiomerically pure, or diastereomerically pure) and stereoisomeric mixtures are encompassed.

The invention encompasses all geometrically-pure forms and geometrically- enriched (i.e. greater than 50% of either E or Z isomer) mixtures, of the compounds disclosed herein. Mixtures include 1 :20, 1 :10, 20:80, 30:70, 40:60 and 50:50 E:Z and Z:E ratios by mole.

As used herein, a racemic mixture means 50% of one enantiomer and 50% of is corresponding enantiomer relative to all chiral centers in the molecule. The invention encompasses all enantiomerically-pure, enantiomerically-enriched, diastereomerically pure, diastereomerically enriched, and racemic mixtures, and diastereomeric mixtures of the compounds of the invention which have chiral center(s).

Enantiomeric and diastereomeric mixtures can be resolved into their component enantiomers or stereoisomers by well known methods, such as chiral- phase gas chromatography, chiral-phase high performance liquid chromatography, crystallizing the compound as a chiral salt complex, or crystallizing the compound in a chiral solvent. Enantiomers and diastereomers can also be obtained from diastereomerically- or enantiomerically-pure intermediates, reagents, and catalysts by well known asymmetric synthetic methods. When the stereochemistry of the disclosed compounds is named or depicted by structure, the named or depicted stereoisomer is at least 60%, 70%, 80%, 90%, 99% or 99.9% by weight pure relative to the other stereoisomers. When a single stereoisomer is named or depicted by structure, the depicted or named stereoisomer is at least 60%, 70%, 80%, 90%, 99% or 99.9% pure. Percent purity by weight is the ratio of the weight of the named stereoisomer over the weight of the named stereoisomer plus the weight of its stereoisomers.

Included in the invention are pharmaceutically acceptable salts of the compounds disclosed herein. The disclosed compounds have basic amine groups and therefore can form pharmaceutically acceptable salts with pharmaceutically acceptable acid(s). Suitable pharmaceutically acceptable acid addition salts of the compounds of the invention include salts of inorganic acids (such as hydrochloric acid, hydrobromic, phosphoric, metaphosphoric, nitric, nitrus, sulfurus, and sulfuric acids) and of organic acids (such as, acetic acid, benzenesulfonic, benzoic, citric, ethanesulfonic, fumaric, gluconic, glycolic, isethionic, lactic, lactobionic, maleic, malic, methanesulfonic, succinic, p- toluenesulfonic, and tartaric acids).

Compounds of the invention with acidic groups such as carboxylic acids can form pharmaceutically acceptable salts with pharmaceutically acceptable base(s). Suitable pharmaceutically acceptable basic salts include ammonium salts, alkali metal salts (such as lithium, sodium and potassium salts) and alkaline earth metal salts (such as magnesium and calcium salts). Compounds with a quaternary ammonium group also contain a counter-anion such as chloride, bromide, iodide, acetate, perchlorate and the like. Other examples of such salts include hydrochlorides, hydrobromides, sulfates, methanesulfonates, nitrates, maleates, acetates, citrates, fumarates, tartrates [e.g. (+)-tartrates, (-)-tartrates or mixtures thereof including racemic mixtures], succinates, benzoates and salts with amino acids such as glutamic acid. The compounds disclosed herein can be prepared by any suitable method known in the art, for example, WO 98/39287; U.S. 4,740,581 ; U.S. 3,639,430; GB974518; Elizbarashvili, E. N., et ah, Chemistry of Heterocyclic Compounds (2005), 41(12), 1543-1544; Simon, Myron S. and Rogers, Jean B., Journal of Organic Chemistry (1961), 26, 4352-5359; Allen, C. F. H., et ah, Journal of the American Chemical Society (1950), 72, 585-588; and Allen, C. F. H. and Wilson, C. V., Journal of Organic Chemistry (1945), 10, 594-602, the entire teachings of which are incorporated herein by reference.

The term "halo" as used herein means halogen and includes chloro, fluoro, bromo and iodo. An "aliphatic group" is non-aromatic, consists solely of carbon and hydrogen and may optionally contain one or more units of unsaturation, e.g., double and/or triple bonds. An aliphatic group may be straight chained, branched or cyclic. When straight chained or branched, an aliphatic group typically contains between about one and about twenty carbon atoms, typically between about one and about ten carbon atoms, more typically between about one and about six carbon atoms. When cyclic, an aliphatic group typically contains between about three and about ten carbon atoms, more typically between about three and about seven carbon atoms. A "substituted aliphatic group" is substituted at any one or more "substitutable carbon atom". A "substitutable carbon atom" in an aliphatic group is a carbon in an aliphatic group that is bonded to one or more hydrogen atoms. One or more hydrogen atoms can be optionally replaced with a suitable substituent group. A "haloaliphatic group" is an aliphatic group, as defined above, substituted with one or more halogen atoms. Suitable substituents on a substitutable carbon atom of an aliphatic group are the same as those for an alkyl group. The term "alkyl" used alone or as part of a larger moiety, such as "alkoxy",

"haloalkyl", "arylalkyl", "alkylamine", "cycloalkyl", "dialkyamine", "alkylamino", "dialkyamino" "alkylcarbonyl", "alkoxycarbonyl" and the like, includes as used herein means saturated straight-chain, cyclic or branched aliphatic group. As used herein, a C1-C6 alkyl group is referred to "lower alkyl," Similarly, the terms "lower alkoxy", "lower haloalkyl", "lower arylalkyl", "lower alkylamine", "lower cycloalkylalkyl", "lower dialkyamine", "lower alkylamino", "lower dialkyamino" "lower alkylcarbonyl", "lower alkoxycarbonyl" include straight and branched, saturated chains containing one to six carbon atoms, and cyclic saturated chains containing three to six carbon atoms,

The term "alkoxy" means -O-alkyl; "hydroxyalkyl" means alkyl substituted with hydroxy; "aralkyl" means alkyl substituted with an aryl group; "alkoxyalkyl" mean alkyl substituted with an alkoxy group; ''alkylamine" means amine substituted with an alkyl group; "cycloalkylalkyl" means alkyl substituted with cycloalkyl; "dialkylamine" means amine substituted with two alkyl groups; "alkylcarbonyl" means -C(O)-R, wherein R is alkyl; "alkoxycarbonyl" means -C(O)-OR, wherein R is alkyl; and where alkyl is as defined above. The term "dialkylamine" includes a cyclic amine, such as a piperidyl group.

The terms "haloalkyl" and "haloalkoxy" means alkyl or alkoxy, as the case may be, substituted with one or more halogen atoms. The term "halogen" means F, Cl, Br or I. Preferably the halogen in a haloalkyl or haloalkoxy is F.

An "alkylene group" is represented by -[CH₂]_Z-, wherein z is a positive integer, preferably from one to eight, more preferably from one to four.

An "alkenylene group" is an alkylene in which at least a pair of adjacent methylenes are replaced with -CH=CFI-.

An "alkynylene group" is an alkylene in which at least a pair of adjacent methylenes are replaced with -C=C-. The term "aryl group" used alone or as part of a larger moiety as in

"aralkyl", "aralkoxy", or "aryloxyalkyl", means carbocyclic aromatic rings. The term "carbocyclic aromatic group" may be used interchangeably with the terms "aryl", "aryl ring" "carbocyclic aromatic ring", "aryl group" and "carbocyclic aromatic group". An aryl group typically has six - fourteen ring atoms. A "substituted aryl group" is substituted at any one or more substitutable ring atom. The term "Cό-πaryl" as used herein means a monocyclic, bicyclic or tricyclic carbocyclic ring system containing from 6 to 14 carbon atoms and includes phenyl, naphthyl, anthracenyl, 1 ,2-dihydronaphthyl, 1,2,3,4-tetrahydronaphthyl, fluorenyl, indanyl, indenyl and the like.

The terms "heterocyclic ring" and "heterocyclic group" refer to both heteroaromatic ring groups and non-aromatic, heterocyclic ring groups. The terms "heteroaryl", "heteroaromatic", "heteroaryl ring", "heteroaryl group" and "heteroaromatic group", used alone or as part of a larger moiety as in "heteroaralkyl" or "heteroarylalkoxy", refer to aromatic ring groups having five to fourteen ring atoms selected from carbon and at least one (typically 1 -4, more typically 1 or 2) heteroatom (e.g., oxygen, nitrogen or sulfur). They include monocyclic rings and polycyclic rings in which a monocyclic heteroaromatic ring is fused to one or more other carbocyclic aromatic or heteroaromatic rings. The term "5-14 membered heteroaryl" as used herein means a monocyclic, bicyclic or tricyclic ring system containing one or two aromatic rings and from 5 to 14 atoms of which, unless otherwise specified, one, two, three, four or five are heteroatoms independently selected from N. NH, N(Ci_-6alkyl), O and S and includes thienyl, furyl, pyrrolyl, pyrididyl, indolyl, quinolyl, isoquinolyl, tetrahydroquinolyl, benzofuryl, benzothienyl and the like.

Examples of monocyclic 5-6 membered heteroaryl groups include furanyl (e.g., 2-furanyl, 3-furanyl), imidazolyl (e.g., iV-imidazolyl, 2-imidazolyl, 4-imidazolyl, 5-imidazolyl), isoxazolyl( e.g., 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl), oxadiazolyl (e.g., 2-oxadiazolyl, 5-oxadiazolyl), oxazolyl (e.g., 2-oxazolyl, 4-oxazolyl, 5- oxazolyl), pyrazolyl (e.g., 3-pyrazolyl, 4-pyrazolyl), pyrrolyl (e.g., 1 -pyrrolyl, 2- pyrrolyl, 3-pyrrolyl), pyridyl (e.g., 2-pyridyl, 3-pyridyl, 4-pyridyl), pyrimidinyl (e.g., 2-pyrimidinyl, 4-pyrimidinyl, 5-pyrimidinyl), pyridazinyl (e.g., 3-pyridazinyl), thiazolyl (e.g., 2-thiazolyl, 4-thiazolyl, 5-thiazolyl), triazolyl (e.g., 2-triazolyl, 5- triazolyl), tetrazolyl (e.g., tetrazolyl), thienyl (e.g., 2-thienyl, 3-thienyl), pyrimidinyl, pyridinyl and pyridazinyl. Examples of polycyclic aromatic heteroaryl groups include carbazolyl, benzimidazolyl, benzothienyl, benzofuranyl, indolyl, quinolinyl, benzotriazolyl, benzothiazolyl, benzoxazolyl, benzimidazolyl, isoquinolinyl, indolyl, isoindolyl, acridinyl, or benzisoxazolyl. Other examples for the aryl and heteroaryl groups include:

wherein each of rings A1-Z7 is optionally substituted. It is noted that, as shown above, rings O1-Z7 can be attached to their designated atom through any ring carbon of the rings which is not at a position bridging two aryl groups. For example,

means that the group is attached to its designated atom through either ring Ql or ring Rl. Yet other examples for the aryl and heteroaryl groups include:

wherein each of rings Al-Nl is optionally substituted. More specific values for the aryl and heteroaryl groups include:

wherein each of rings Al-El is optionally substituted. Even more specific values for the aryl and heteroaryl groups include:

wherein each of rings Al-Cl is optionally substituted. An optionally substituted ring Al is the most common specific value for each of the aryl group, including the C₆-H aryl group.

As used herein, the term "non-aromatic heterocyclic group" means a monocyclic (typically having 3- to 10-members) or a polycyclic (typically having 7- to 20-members) heterocyclic ring system which is a non-aromatic ring. A 3- to 10-membered heterocycle can contain up to 5 heteroatoms; and a 7- to 20-membered heterocycle can contain up to 7 heteroatoms. Typically, a heterocycle has at least one carbon atom ring member. Each heteroatom is independently selected from nitrogen, which can be oxidized (e.g., N(O)) or quaternized; oxygen; and sulfur, including sulfoxide and sulfone. The heterocycle may be attached via any heteroatom or carbon atom. Representative heterocycles include morpholinyl, thiomorpholinyl, pyrrolidinonyl, pyrrolidinyl, piperidinyl, piperazinyl, hydantoinyl, valerolactamyl, oxiranyl, oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, tetrahydropyrindinyl, tetrahydropyrimidinyl, tetrahydrothiophenyl, tetrahydrothiopyranyl, and the like.

The aryl group, and the aromatic and non-aromatic heteroaryl groups, unless otherwise indicated, can be optionally substituted with one or more substituents selected from the group consisting of halogen, nitro, cyano, hydroxy, Ci_-20 alkyl, C₂. 2o alkenyl, C2-20 alkynyl, amino, C]_-2O alkylamino, C|-2₀ dialkylamino, Ci_-20 alkoxy, (Ci-IO alkoxy)Ci_-2o alkyl, Ci_-2o haloalkoxy, (Ci-io haloalkoxy)Ci_-2o alkyl and C1.20 haloalkyl. Typical substituents include halogen, nitro, cyano, hydroxy, Cj.₁₀ alkyl, C2-10 alkenyl, C₂-₁₀ alkynyl, amino, C].₁₀ alkylamino, Ci.jo dialkylamino, Cj.₁₀ alkoxy, (Ci_-6 alkoxy)C _{M O} alkyl, Ci-io haloalkoxy, (Ci_-6 haloalkoxy)Ci-io alkyl and Ci-io haloalkyl. More typical substituents include C].1₀ alkyl, -OH, C₁-Io alkoxy, C₁-Jo haloalkyl, halogen, Ci_i₀haloalkoxy,amino, nitro and cyano.

A "subject^"' is preferably a human but can also be a veterinary animal, farm animal or laboratory animal in need of treatment, for example, for a viral infection, cancer or restenosis.

"Treatment" or "treating" refers to both therapeutic and prophylactic treatment.

An "effective amount" is the quantity of a disclosed compound disclosed herein in which a beneficial clinical outcome (prophylactic or therapeutic) is achieved when the compound is administered to a subject in need of treatment. In the treatment of the invention, a "beneficial clinical outcome" includes a reduction in the severity of the symptoms associated with the disease (e.g., fever), a reduction in the longevity of the disease and/or a delay in the onset of the symptoms associated with the disease compared with the absence of the treatment. The precise amount of the compound administered to a subject will depend on the type and severity of the disease or condition and on the characteristics of the subject, such as general health, age, sex, body weight and tolerance to drugs. It will also depend on the degree, severity and type of disease or condition. The skilled artisan will be able to determine appropriate dosages depending on these and other factors. Effective amounts of the compounds disclosed herein typically range between about O.lmg/kg body weight per day and about 1000 mg/kg body weight per day, and preferably between 1 mg/kg body weight per day and 100 mg/kg body weight per day. The method of the present invention can be a mono-therapy where a compound disclosed herein is the only therapeutically active drug administered to a subject. Alternatively, the method of the invention is a co-therapy with one or more of other therapeutically active drugs or therapies known in the art for treating a viral infection, cancer or restenosis. When the compounds disclosed herein are combined with other anti-viral drugs known in the art, other anti-cancer drugs known in the art, or other anti-restenosis drugs known in the art, they can be administered contemperaneously. As used herein, "administered contemporaneously" means that two substances are administered to a subject such that they are both biologically active in the subject at the same time. The exact details of the administration will depend on the pharmacokinetics of the two substances in the presence of each other, and can include administering one substance within a period of time of one another, e.g., 24 hours of administration of the other, if the pharmacokinetics are suitable. Designs of suitable dosing regimens are routine for one skilled in the art. In particular embodiments, two substances will be administered substantially simultaneously, i.e. within minutes of each other, or in a single composition that comprises both substances. Alternatively, the two agents can be administered separately, such that only one is biologically active in the subject at the same time. In a specific embodiment, the compounds disclosed herein are used for treating viral infection in combination with an interferon or an interferon inducer (e.g., α-interferon inducer or a γ-interferon inducer). Typical examples of the known interferon inducers include various viruses, bacteria (particularly Gram-negative bacteria), lipopolysaccharide endotoxin of said bacteria, metabolic products of molds, polysaccharides and double stranded-RNA, imiquimod, resiquimod and bacterial CpG oligonucleotides, such as CpG7907. In another specific embodiment, the method of the invention is a co-therapy with one or more of other therapeutically active drugs or therapies known in the art for treating cancer. Anticancer therapies that may be used in combination with the compound of the invention include surgery, radiotherapy (including, but not limited to, gamma-radiation, neutron beam radiotherapy, electron beam radiotherapy, proton therapy, brachytherapy, and systemic radioactive isotopes) and endocrine therapy. Anticancer agents that may be used in combination with the the compounds of the invention include biologic response modifiers (including, but not limited to, interferons, interleukins, and tumor necrosis factor (TNF)), hyperthermia and cryotherapy, agents to attenuate any adverse effects (e.g., antiemetics), and other approved chemotherapeutic drugs (e.g. taxol and analogs thereof).

The compounds disclosed herein can be administered to a patient in a variety of forms depending on the selected route of administration, as will be understood by those skilled in the art. The compounds disclosed herein may be administered, for example, by oral, parenteral, buccal, sublingual, nasal, rectal, patch, pump or transdermal administration and the pharmaceutical compositions formulated accordingly. Parenteral administration includes intravenous, intraperitoneal, subcutaneous, intramuscular, transepithelial, nasal, intrapulmonary, intrathecal, rectal and topical modes of administration. Parenteral administration can be by continuous infusion over a selected period of time. The compounds disclosed herein can be suitably formulated into pharmaceutical compositions for administration to a subject. The pharmaceutical compositions optionally include one or more pharmaceutically acceptable carriers and/or diluents therefor, such as lactose, starch, cellulose and dextrose. Other exeipients, such as flavoring agents; sweeteners; and preservatives, such as methyl, ethyl, propyl and butyl parabens, can also be included. More complete listings of suitable exeipients can be found in the Handbook of Pharmaceutical Exeipients (5^th Ed., Pharmaceutical Press (2005)). A person skilled in the art would know how to prepare formulations suitable for various types of administration routes. Conventional procedures and ingredients for the selection and preparation of suitable formulations are described, for example, in Remington's Pharmaceutical Sciences (2003 - 20th edition) and in The United States Pharmacopeia: The National Formulary (USP 24 NFl 9) published in 1999. The carriers, diluents and/or excipients are "acceptable" in the sense of being compatible with the other ingredients of the pharmaceutical composition and not deleterious to the recipient thereof.

Typically, for oral therapeutic administration, a compound disclosed herein may be incorporated with excipient and used in the form of ingestible tablets, buccal tablets, troches, capsules, elixirs, suspensions, syrups, wafers, and the like.

Typically for parenteral administration, solutions of a compound disclosed herein can generally be prepared in water suitably mixed with a surfactant such as hydroxypropylcellulose. Dispersions can also be prepared in glycerol, liquid polyethylene glycols, DMSO and mixtures thereof with or without alcohol, and in oils. Under ordinary conditions of storage and use, these preparations contain a preservative to prevent the growth of microorganisms.

Typically, for injectable use, sterile aqueous solutions or dispersion of, and sterile powders of, a compound disclosed herein for the extemporaneous preparation of sterile injectable solutions or dispersions.

For nasal administration, the compounds disclosed herein can be formulated as aerosols, drops, gels and powders. Aerosol formulations typically comprise a solution or fine suspension of the active substance in a physiologically acceptable aqueous or non-aqueous solvent and are usually presented in single or multidose quantities in sterile form in a sealed container, which can take the form of a cartridge or refill for use with an atomizing device. Alternatively, the sealed container may be a unitary dispensing device such as a single dose nasal inhaler or an aerosol dispenser fitted with a metering valve which is intended for disposal after use.

Where the dosage form comprises an aerosol dispenser, it will contain a propellant which can be a compressed gas such as compressed air or an organic propellant such as fluorochlorohydrocarbon. The aerosol dosage forms can also take the form of a pump-atomizer.

For buccal or sublingual administration, the compounds disclosed herein can be formulated with with a carrier such as sugar, acacia, tragacanth, or gelatin and glycerine, as tablets, lozenges or pastilles. For rectal administration, the compounds disclosed herein can be formulated in the form of suppositories containing a conventional suppository base such as cocoa butter.

The compounds disclosed herein can be formulated alone or for contemporaneous adminstration with other agents for treating viral infections. Therefore, in another aspect, a compound disclosed herein or a pharmaceutically acceptable salt thereof, and another anti-viral agent known in the art can be included in a pharmaceutical composition.

The invention is illustrated by the following examples, which are not intended to be limiting in any way.

EXEMPLIFICATION

Example 1 : High Throughput Screening (HTS)

HTS campaigns against several different compound libraries at the National Screening Library for the Regional Centers of Excellence in Biodefense and Emerging Infectious Diseases (NSRB) at Harvard University produced 16 novel hits, 12 of which had RNase L-activating ability that exceeded that of the initial two hits, compounds 1 & 2 reported in Proceedings of the National Academy of Sciences article¹. These RNase L activators can be prototypes for a novel class of broad- spectrum antiviral agents.

Methods. HTS. HTS was performed by a modification of our previously described FRET assay for RNase L activity¹⁵. The RNA substrate for the FRET assays was a 36 nucleotide synthetic oligoribonucleotide, 6-FAM-UUA UCA AAU UCU UAU UUG CCC CAU UUU UUU GGU UUA-BHQ-I (SEQ ID. NO. 1, Integrated DNA Technologies, Inc., Coralville, IA). Recombinant human RNase L expressed from a baculovirus vector in insect cells was purified by FPLC as described previously¹⁵'¹⁶. HTS was performed in black polypropylene 384-well plates. Reaction mixtures contained 25 nM RNase L and 100 nM FRET probe (K_m = 75 nM) in a final volume of 50 μl cleavage buffer (25 mM Tris HCl pH 7.4, 100 mM KCl, 10 mM MgCl₂, 50 μM ATP, 7 mM β-mercaptoethanol). Test compounds or 2-5A were added with a 96-well standard replicator (Incyte, Wilmington, DE). Stock concentrations of compounds were 10 mM (NCI library) or 5 mg/ml (ChemBridge compounds) in 100% DMSO and the final concentrations of compounds during HTS were 50 to 65 μM. Trimeric 2-5 A (10 nM), Z'-factor > 0.8, was used as a positive control in every screening plate. The assay plates were gently agitated, ccntrifuged briefly at 150xg and incubated at 22⁰C for up to 2 h. Fluorescence was measured with a Wallac 1420 Victor2 multilabel counter (Perkin-Elmer Life Sciences, Shelton, CT) (excitation 485 nm; emission 535 nm). False positives were eliminated by rescreening compounds in the absence of RNase L.

Algorithm. For a pick to be included in our cherry pick list, all the above criteria we re fulfilled for both the replicates (assays were in duplicate) and for both criteria, This was done to reduce the number of false positives.

FRET based HTS of different chemical libraries (Fig. 2) were done in duplicate with compound alone control (no RNase L) so as to eliminate any small molecules that auto-fluoresce; or which may hydrolyze the probe on its own. In addition these controls we used for background subtraction. Delta Z scores for the [background subtracted, absolute fluorescence signal] and [fold-increase in signal over RNase L alone control] were calculated from data mined in duplicate as follows:

Background (compound alone) from each experimental well (performed in duplicate) was subtracted using the minus RNase L control (performed in duplicate). All statistical analyses was performed in Sigma plot 10 automated using macros command line for analysis of each plate separately. The ΔZ-score for the screening was evaluated using following formula:

ΔZ = [(signal with RNase L) - (signal without RNase L) - (median fluorescence of the plate)]/Standard deviation

In a statistical terms:

ΔZ = [(ΔXi-μ_j)/σ,], where i = well number; j = plate number ΔXi = [(signal with RNase L) - (signal without RNase L) for the i^th well] μ_j is the median signal for j^th plate

O₁ is the standard deviation of the j^th plate Similarly,

Fold increase of the signal = [(signal with compound and RNase L) - (signal without RNase L)]/ (Mean signal of the well containing RNase L alone)

Once each plate was analyzed, data from each plate was mined using following criteria

( 1 ) ΔZ-score of Replicate A must be > 3.0

(2) ΔZ-score of Replicate B must be > 3.0

(3) Fold increase of the signal > 2.0

The "Cherry Pick" analysis using this algorithm produced 16 hits, Compounds A-P. The structures of these Compounds A-P are shown above.

Example 2: Identification and characterization of an RNase L activator with affinity for the kinase-like region

(a) Activation of RNase L. RNase L activity was measured in vitro by FRET assays with 5 μM of compounds obtained at NSRB (compounds A to P) or 5 μM of Compounds C 1 and C2 in comparison to 1 nM of 2-5 A molecule, (2'-5')p₃A₃ experiments were performed in triplicate mean fluorescence. The results were plotted with error bars SD in FIG. 2(a).

(b) Dose dependence of the most potent 'Hit', compound J. RNase L activity was measured in vitro by FRET assays with increasing concentration of compound J. An

EC50 of 3.3 μM was calculated using non-linear sigmoid-fit with Prizm software (see FIG. 2(b)).

(c) Suppression of viral replication by compound J is RNase L dependent. Rnaset^/+ and Rnasel^'1' mef were infected with EMCV (0.05 MOI) for 1 h followed by treatment with different concentrations of compound J. Viral suppression (50% at 3.5 μM compound J) was obtained in the wild type mef only (see Fig. 2(c)). (d) Compound J binds to the kinase-endonuclease (KEN) domain of RNase L. Surface plasmon resonance studies were performed on different domains of hexa-histidine tagged RNase L immobilized on Ni-NTA chips to at least 50-60 RUs, washed with buffer containing 10 mM of imidazole, and 5 μM of compound J was delivered to the RNase L coated chips. In Fig. 2(d), the sensogram for RNase L WT, NΔ335, NΔ392 NΔ571 and CΔ335 is shown as a function of time and response unit.

As described above, abilities of Compounds A-P to activate RNase L was confirmed in FRET assays performed in triplicate {see Fig, 2(a)). Direct comparisons were made between these novel hits and the prior Compounds 1 and 2 as well as with trimeric 2-5 A. As shown in FIG. 2(a), 12 of the 16 novel hits had activities as great or greater than compounds 1 and 2 (referenced as "Cl " and "C2", respectively, in FIG. 2(a)):

Cofflpajni 1 , C-S968451 and

One of the compounds, Compound J, had activity that was 5- to 15-fold greater than compounds 1 and 2, respectively.

As shown in FIG. 2(c), Compound J was a potent inhbitor of emcv replication in

Rnasel^+/+ mef, but not in Rnasel^{' '} mef, demonstrating that inhibition by compound J was mediated through RNase L. Interestingly, compound J was found by surface plasmon resonance studies to bind in the region of RNase L between amino acid residues 392-577 containing the protein kinase-like domains (see Fig. 2(d)). These findings are in sharp contrast to compounds 1 and 2 which binding to ankyrin repeats 2 & 4, similar to 2-5A⁽'\ Furthermore, the level of RNase L activation with 5 μM Compound J was equal to that of 1 nM 2-5A (optimal dose). Dose-response experiments showed that Compound J had an EC₅₀ of 3.3 μM, in comparison to an EC₅₀ of 0.2 nM for 2-5 A

(Fig. 3). Compounds JR4, JR5, and JR6 which are related to Compound J were compared for their abilities to activate RNase L by a gel-based version of the same

FRET assay (Fig. 4). Results show that 0.5 μM of Compounds J, JR4, JR5, and JR6 gave a similar level of activation of RNase L (lanes 3-18). 2-5 A gave superior activation of RNase L as expected (lane 2).

EC50's for Compounds JR4 and JR5 in the FRET RNase L assay were 2.970 μM and 12.68 μM, respectively. Fig. 5 shows the activity of a compound (JR4) in an RNase L activation assay. JR4 had a closely related structure to compound J and similar level of activity. As described above, a number of the tested compounds had lower EC50's than those of compounds 1 and 2. Not being bound to a particular theory or mechanism, it is predicted that these compounds have a unique mechanism of action that may not involve the 2-5A binding site of RNase L. Computer-assisted docking studies and binding simulations indicate that the novel hits did not dock with the 2- 5 A binding domain (ANK) (data not shown) but had a different binding sites in RNase L. These are unexpected findings, because there is no prior literature suggesting such a mechanism of activation of RNase L other than through the 2-5 A binding domain. Thus, they may enhance the activity of the natural activator, 2-5 A, and indirectly enhance the activity of interferons which induce expression of 2-5 A synthetase (OAS) in vivo. These compounds are predicted to have broad-spectrum antiviral activity that could be used in combination therapy with either interferons per se, or with interferon inducers,

REFERENCES INCORPORATED HEREIN BY REFERENCE The entire teachings of the following references are incorporated herein by reference.

1. Thakur, C. S. et al. Small-molecule activators of RNase L with broad- spectrum antiviral activity. Proc Natl Acad Sci USA 104, 9585-90 (2007). 2. Stark, G. R., Kerr, I. M., Williams, B. R., Silverman, R. H. & Schreiber, R. D. How cells respond to interferons. Annu Rev Biochem 67, 227-64 (1998).

3. Horvath, C. M, Weapons of STAT destruction. Interferon evasion by paramyxovirus V protein. Eur J Biochem 271, 4621-8 (2004).

4. Silverman, R. H. Viral Encounters with OAS and RNase L during the IFN Antiviral Response. J Virol (2007). 5. Kerr, I. M. & Brown, R. E. pppA2'p5'A2'p5'A: an inhibitor of protein synthesis synthesized with an enzyme fraction from interferon-treated cells. Proc Natl Acad Sci USA 75, 256-60 (1978).

6. Knight, M. et al. Radioimmune, radiobinding and HPLC analysis of 2-5 A and related oligonucleotides from intact cells. Nature 288, 189-92 (1980).

7. Rice, A. P., Kerr, S. M., Roberts, W. K., Brown, R. E. & Kerr, I. M. Novel 2',5'-oligoadenylates synthesized in interferon-treated, vaccinia virus- infected cells. J Virol 56, 1041-4 (1985).

8. Cayley, P. J., Davies, J. A., McCullagh, K. G. & Kerr, I. M. Activation of the ppρ(A2'p)nA system in interferon-treated, herpes simplex virus-infected cells and evidence for novel inhibitors of the ppp(A2'p)nA-dependent RNase. Eur JBiochem 143, 165-74 (1984).

9. Zhou, A., Hassel, B. A. & Silverman, R. II. Expression cloning of 2-5A- dependent RNAase: a uniquely regulated mediator of interferon action. Cell 72, 753-65 (1993).

10. Player, M. R. & Torrence, P. F. The 2-5A system: modulation of viral and cellular processes through acceleration of RNA degradation. Pharmacol Ther 78, 55-1 13 (1998).

1 1. Wreschner, D. H., McCauley, J. W., Skehel, J. J. & Kerr, I. M. Interferon action— sequence specificity of the ppp(A2'p)nA-dependent ribonuclease.

Nature 289, 414-7 (1981).

12. Floyd-Smith, G., Slattery, E. & Lengyel, P. Interferon action: RNA cleavage pattern of a (2'-5')oligoadenylate— dependent endonuclease. Science 212, 1030-2 (1981). 13. Beattie, E. et al. Reversal of the interferon-sensitive phenotype of a vaccinia virus lacking E3L by expression of the reovirus S4 gene. J Virol 69, 499-505 (1995).

14. Min, J. Y. & Krug, R. M. The primary function of RNA binding by the influenza A virus NSl protein in infected cells: Inhibiting the 2'-5' oligo (A) synthetase/RNase L pathway. Proc Natl Acad Sci USA 103, 7100-5 (2006).

15. Thakur, C. S., Xu, Z., Wang, Z., Novince, Z. & Silverman, R. H. A convenient and sensitive fluorescence resonance energy transfer assay for RNase L and 2',5' oligoadenylates. Methods MoI Med 116, 103-13 (2005).

16. Dong, B. et al. Intrinsic molecular activities of the interferon-induced 2-5 A- dependent RNase. J Biol Chem 269, 14153-8 (1994).

Claims

CLAIMSWhat is claimed is:

1. A method for activating RNase L in a subject in need thereof, comprising administering to the subject an effective amount of a compound represented by the following structural formula or a pharmaceutically acceptable salt thereof:

wherein:

Q is -OR^Z, -SR^Z or -NR/ 3rIT,4.;

R¹ and R² are each independently -H, an optionally substituted Ci_-I0 aliphatic group, an optionally substituted aryl group or an optionally substituted heterocyclic group;

R³ and R⁴ are each independently -H, an optionally substituted C]_-1Q aliphatic group, an optionally substituted aryl group or an optionally substituted heterocyclic group, or, R³ and R⁴, taken together with the nitrogen atom to which R³ and R⁴ are attached, form an optionally substituted, non-aromatic, heterocyclic ring; and each of rings A and B is independently and optionally substituted, provided that when Q is -NH₂, R¹ is then an optionally substituted cyclic alkyl group, an optionally substituted aryl group or an optionally substituted heterocyclic group.

2. The method of Claim 1, wherein the activation of RNase L treats a viral infection.

3. The method of Claim 2, wherein the viral infection is caused by a virus with a single-stranded RNA(s) genome.

4. The method of Claim 3, wherein the virus is orthomyxoviruses, paramyxoviruses, rhabdoviruses, togaviruses, picornaviruses, flaviviruses, bunyaviruses, retroviruses, filoviruses or hepatitis B virus.

5. The method of Claim 3, wherein the viral infection is caused by a virus with a DNA genome.

6. The method of Claim 5, wherein the virus is human papillomavirus, herpes simplex virus- 1 and -2, cytomegalovirus, or human herpesvirus-8.

7. The method of Claim 5, wherein the virus is Variola virus, Monkeypox virus, Molluscum eontagiosum virus, Eψstein-Barr virus, adenovirus, varicella-zoster virus, human herpesvirus 6, human herpesvirus 7, Bl 9 parvovirus, adeno-associated virus, BK virus, and JC virus, human papillomavirus, herpes simplex virus- 1 and -2, cytomegalovirus, or human herpesvirus-8.

8. The method of Claim 1 , wherein the activation of RNase L treats cancer.

9. The method of Claim 8, wherein the cancer is prostate cancer, ovarian cancer, brain cancer or bone cancer.

10. The method of Claim 1, wherein the activation of RNase L treat restenosis.

1 1. The method of any one of Claims 1-10, wherein each of rings A and B is optionally and independently substituted with one or more substituents selected from the group consisting of halogen, Ci. io alkyl, C_2-I0 alkenyl, C₂- 10 alkynyl, amino, Ci-io alkylamino, Ci.io dialkylamino, C].₁₀ alkoxy, nitro, cyano , hydroxy, Ci-I₀ alkoxycarbony 1 , Ci-I₀ alkyl carbonyl , C i . i o haloalkoxy ,

(Ci.iohaloakoxy)Ci.io alkyl, Ci-I₀ haloalkyl, phenyl, -(CH₂)_p-phenyl, -(CH₂)_p-(5-6 membered heteroaryl) and 5-6 membered heteroaryl, wherein p is 1 , 2, 3 or 4.

12. The method of Claim 1 1 , wherein one or more substituents for said aliphatic groups represented by R¹, R², R³ and R⁴ are each independently selected from the group consisting of halogen, Ar¹, -NO₂, -CN, -NCS, -C(O)OR¹⁰, -C(O)R¹⁰, -C(S)R¹⁰, -OC(O)R¹⁰, -C(O)N(R¹ ')₂, -C(S)N(R¹ ')₂, -S(O)R¹², -S(O)₂R¹², -SO₃R¹², -SO₂N(R¹ \ -SO₂N(R¹ ')-NRⁿ, -OR¹⁰, -SR¹⁰, -N(R^{1 !})₂, -NR^{1 1}C(O)R¹⁰, -NR¹¹S(O)R¹²,

-NR^{1 1}C(O)OR¹², -N(R^π)C(0)N(R^π)₂, -NR^{1 1}SO₂N(R¹ ')₂, and -NR^{1 1}SO₂R¹²; one or more substituents for said aryl and heterocyclic groups represented by R¹, R², R³ and R⁴ are each independently selected from the group consisting of halogen, Ak',Ar', -NO_2, -CN, -NCS. -C(O)OR¹⁰, -C(O)R¹⁰, -C(S)R¹⁰, -OC(O)R¹⁰,

-C(O)N(R¹ ')₂, -C(S)N(R¹ % -S(O)R¹², -S(O)₂R¹², -SO₃R¹¹, -SO₂N(R¹ ')₂, -SO₂N(R¹ ')-NR^π, -OR¹⁰, -SR¹⁰, -N(R¹ ')₂, -NR^{1 1}C(O)R¹⁰, -NR^{1 1}S(O)R¹², -NR^{1 1}C(O)OR¹², -N(R")C(O)N(R^U)₂, -NR¹¹ SO₂N(R^{1 ]})₂, -NR^{1 1}SO₂R¹², -0-[CH₂]_pl-0-, -S-[CH₂]_P-S- and -[CH₂Iq-; and one or more substituents for said non-aromatic heterocyclic group formed from R³ and R⁴ together with the nitrogen atom to which R³ and R⁴ are attached are each independently selected from the group consisting of halogen, oxo, Cj ._J0 alkyl, C_2-10 alkenyl, C_2-I0 alkynyl, amino, Ci. io alkylamino, Ci.io dialkylamino, Cj.io alkoxy, nitro, cyano, hydroxy, C_MO alkoxycarbonyl, C M₀ alkyl carbonyl, C M₀ haloalkoxy, (Ci.i₀haloakoxy)Ci.|₀ alkyl, C_{M 0} haloalkyl, phenyl, -(CH₂)_p-phenyl and 5-6 membered heteroaryl, wherein each R¹⁰ independently is: i) hydrogen; ii) a phenyl or a 5-6 membered heteroaryl group each optionally and independently substituted with one or more substituents selected from the group consisting of halogen, nitro, cyano, hydroxy, Ci_-6 alkyl, C₂-₆ alkenyl, C₂-₆ alkynyl, amino, Ci-₆ alkylamino, Ci-6 dialkylamino, Ci_-6 alkoxy, (Ci_-6 alkoxy)C _I-6 alkyl, Ci_-6 haloalkoxy, Ci._ό haloalkyi and (Ci-₆ haloalkoxy)C].₆ alkyl; or iii) a C]- io alkyl group optionally substituted with one or more substituents selected from the group consisting of halogen, hydroxyl, amino, Ci_-6 alkylamino, Ci.₆ dialkylamino, Ci.₆ alkoxy, nitro, cyano, C).₆ alkoxycarbonyl, Ci.₆ alkylcarbonyl and Ci_-6 haloalkoxy; and each R¹ ' independently is R¹⁰, -CO₂R¹⁰, -SO₂R¹⁰ or -C(O)R¹⁰, or

-N(R^π)₂ taken together is an optionally substituted non-aromatic heterocyclic group; and each R¹² independently is: i) hydrogen; ii) a phenyl or a 5-6 membered heteroaryl group each optionally and independently substituted with one or more substituents selected from the group consisting of halogen, nitro, cyano, hydroxy, Ci_-6 alkyl, C_2-6 alkenyl, C₂-_O alkynyl, amino, Ci_-6 alkylamino, Cj-g dialkylamino, Cj_-6 alkoxy, (Ci_₆ alkoxy)C|.₆ alkyl, Ci_-6 haloalkoxy, Ci_-6 haloalkyl and (Cj .β haloalkoxy)Cj-₆ alkyl; or iii) a Ci-io alkyl group optionally substituted with one or more substituents selected from the group consisting of halogen, hydroxyl, amino, C i.₆ alkylamino, Ci-_δ dialkylamino, C]_-6 alkoxy, nitro, cyano, Ci_-6 alkoxy carbonyl, Ci-₆ alkylcarbonyl and C_1-6 haloalkoxy; and each Ar¹ independently is a phenyl or a 5-6 membered heteroaryl group optionally and independently substituted with one or more substituents selected from the group consisting of halogen, nitro, cyano, hydroxy, Ci_-6 alkyl, C_2-6 alkenyl, C₂-₆ alkynyl, amino, Ci_-6 alkylamino, Cj_-6 dialkylamino, C i-6 alkoxy, (Ci.₆ alkoxy)Ci_6 alkyl, C]_-6 haloalkoxy, (Cj.₆ haloalkoxy)Ci_-6 alkyl and Cj.₆ haloalkyl; each Ak¹ independently is a C]_-6 aliphatic group optionally substituted with one or more substituents selected from the group consisting of halogen, amino, Ci_-6 alkylamino, C]_-6 dialkylamino, Ci_-6 alkoxy, nitro, cyano, hydroxy, Ci_-6 haloalkoxy, Ci_-6 alkoxycarbonyl, Ci_-6 alkylcarbonyl and

C i-₆ haloalkyl; each p' independently is 1 , 2, 3 or 4; and each q' independently is 3, 4, 5 or 6.

13. The method of Claim 12, wherein R¹ is -H or an optionally substituted C _{M O} aliphatic group.

14. The method of Claim 13, wherein:

Q is -OR² or -SR²; and each R² independently is -H; a C1 -C6 alkyl group optionally substituted with one or more substituents selected from the group consisting of halogen, amino, Ci_-6 alky lamino, Ci_-6 dialkylamino, Ci_-6 alkoxy, nitro, cyano, hydroxy, Ci_-6 haloalkoxy, Ci_-6 alkoxycarbonyl, Ci_-6 alkylcarbonyl and C i-₆ haloalkyl; a phenyl group optionally substituted with one or more substituents selected from the group consisting of halogen, nitro, cyano, hydroxy, Ci_-6 alkyl, C2-6 alkenyl, C_2-6 alkynyl, amino, Ci.₆ alkylamino, Ci.₆ dialkylamino, Ci_-6 alkoxy, (Ci_-6 alkoxy)Ci_-6 alkyl, C)_-6 haloalkoxy, (Ci_-6 haloalkoxy)C[_6 alkyl and C]_-6 haloalkyl; or a 5-6 membered heteroaryl group optionally substituted with one or more substituents selected from the group consisting of halogen, nitro, cyano, hydroxy, Ci_-6 alkyl, C_2-6 alkenyl, C₂-₆ alkynyl, amino, Ci_-6 alkylamino, Ci_-6 dialkylamino, d.₆ alkoxy, (Ci_-6 alkoxy)C i_-6 alkyl, Cj_-6 haloalkoxy, (C)_-6 haloalkoxy)Ci_-6 alkyl and Cj_-6 haloalkyl.

15, The method of Claim 14, wherein each R independently is -H or an optionally substituted C1-C6 alkyl group.

16. The method of Claim 15, wherein R is -H or an optionally substituted Cl- C6 alkyl group.

17. The method of Claim 13, wherein the compound is represented by the following structural formula or a pharmaceutically acceptable salt thereof:

wherein:

R³ and R⁴ are each independently -H, an optionally substituted aliphatic group, or R³ and R⁴, taken together with the nitrogen atom to which R³ and R are attached, form an optionally substituted, non-aromatic, heterocyclic ring.

18. The method of Claim 17, wherein rings A and B are optionally and independently substituted with one or more substituents selected from the group consisting of halogen, Ci.₆ alkyl, C_2-6 alkenyl, C₂-_O alkynyl, amino, Ci_-6 alkylamino, Ci-₆ dialkylamino, Ci^ alkoxy, nitro, cyano, hydroxy, Ci_-6 alkoxycarbonyl, Ci.g alkylcarbonyl, Ci_-6 haloalkoxy, (Ci_-6 haloakoxy)C|_-6 alkyl, Ci_-6 haloalkyl, phenyl and benzyl.

19. The method of Claim 18, wherein the compound is represented by a structural formula selected from:

or a pharmaceutically acceptable salt thereof, wherein k and n are each independently 1, 2, 3 or 4; and each of rings D and E is independently and optionally substituted .

20. The method of Claim 19, wherein R³ and R⁴ are each independently -H, an optionally substituted C1 -C6 alkyl group, or R³ and R⁴, taken together with the nitrogen atom to which R³ and R⁴ are attached, form an optionally substituted, non-aromatic, 5 or 6-membered heterocyclic ring.

21. The method of Claim 20, wherein rings D and E are optionally and independently substituted with one or more substituents selected from the group consisting of halogen, oxo, Ci^ alkyl, amino, Ci-e alkylamino, Ci_-6 dialkylamino, Ci-e alkoxy, cyano, hydroxy, Ci^ haloalkoxy, (Ci_-6 haloakoxy)Ci_-6 aIkyl, Ci_-6 haloalkyl, phenyl and benzyl.

22. The method of Claim 21 , wherein k and n are each independently 1 or 2.

23. The method of Claim 22, wherein rings A and B are optionally substituted with one or more substituents selected from the group consisting of halogen, Ci_-6 alkyl, amino, Ci_₆ alkylamino, Ci.6 dialkylamino, Ci^ alkoxy, nitro, cyano, hydroxy, Ci-_όhaloalkoxy, (Ci-₆haloakoxy)Ci-₆ alkyl and C]_-6 haloalkyl.

24. The method of Claim 23, wherein each of rings D and E is unsubstituted.

25. The method of Claim 24, wherein R³ and R⁴ are each independently -H or Cl-C6 alkyl.

26. The method of Claim 18, wherein the compound is represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein j is 1, 2, 3 or 4; and ring F is optionally substituted.

27. The method of Claim 26, wherein ring F is optionally substituted with one or more substituents selected from the group consisting of halogen, oxo, Ci_-6 alkyl, amino, Ci-_δ alkylamino, Ci-ή dialkylamino, Ci^ alkoxy, cyano, hydroxy, Cι_-6 haloalkoxy, (Ci_-6 haloakoxy)C|_-6 alkyl, Ci.₆ haloalkyl, phenyl and benzyl,

28. The method of Claim 27, wherein R¹ is -H or C1-C6 alkyl.

29. The method of Claim 28, wherein j is 1 or 2.

30. The method of Claim 29, wherein rings A and B are optionally substituted with one or more substituents selected from the group consisting of halogen, Ci_-6 alkyl, amino, Ci.₆ alkylamino, Ci-ό dialkylamino, Ci^ alkoxy, nitro, cyano, hydroxy, Ci_-6haloalkoxy, (Ci_-6 haloakoxy)Ci_-6 alkyl and Cj_-6 haloalkyl.

31. The method of Claim 30, wherein ring F is unsubstituted.

32. A method for activating RNase L in a subject in need thereof, comprising administering to the subject an effective amount of a compound represented by a structural formula selected from:

or a pharmaceutically acceptable salt thereof.

33. The method of Claim 32, wherein the activation of RNase L treats a viral infection.

34. The method of Claim 33, wherein the viral infection is caused by a virus with a single-stranded RNA(s) genome.

35. The method of Claim 34, wherein the virus is orthomyxoviruses, paramyxoviruses, rhabdoviruses, togaviruses, picornaviruses, flaviviruses, bunyaviruses, retroviruses, filoviruses or hepatitis B virus.

36. The method of Claim 34, wherein the viral infection is caused by a virus with a DNA genome.

37. The method of Claim 36, wherein the virus is human papillomavirus, herpes simplex virus- 1 and -2, cytomegalovirus, or human herpesvirus-8.

38. The method of Claim 36, wherein the virus is Variola virus, Monkeypox virus, Molluscum contagiosum virus, Epstein-Barr virus, adenovirus, varicella-zoster virus, human herpesvirus 6, human herpesvirus 7, B19 parvovirus, adeno-associated virus, BK virus, and JC virus, human papillomavirus, herpes simplex virus- 1 and -2, cytomegalovirus, or human herpesvirus-8.

39. The method of Claim 33, wherein the viral infection is an infection of one or more viruses selected from the group consisting of encephalomyocarditis virus, vesicular stomatitis, xenotropic virus, Sendai virus, parainfluenza virus, vaccinia virus and xenotropic MLV related virus.

40. The method of Claim 32, wherein the activation of RNase L treats cancer

41. The method of Claim 40, wherein the cancer is prostate cancer, ovarian cancer, brain cancer or bone cancer.

42. The method of Claim 32, wherein the activation of RNase L treats restenosis.

43. A method for treating a subject, comprising administering to the subject an effective amount of a compound represented by the following structural formula:

wherein:

Q is -OR², -SR² or -NR³R⁴;

R¹ and R² are each independently -H, an optionally substituted Ci_{-I 0} aliphatic group, an optionally substituted aryl group or an optionally substituted heterocyclic group;

R³ and R⁴ are each independently -H, an optionally substituted Ci--_I10 aliphatic group, an optionally substituted aryl group or an optionally substituted heterocyclic group, or, R and R⁴, taken together with the nitrogen atom to which R³ and R⁴ are attached, form an optionally substituted, non-aromatic, heterocyclic ring; and each of rings A and B is independently and optionally substituted, wherein the subject has cancer or restenosis, or is infected by one or more viruses selected from the group consisting of encephalomyocarditis virus, vesicular stomatitis, xenotropic virus, Sendai virus, parainfluenza virus, vaccinia virus and xenotropic MLV related virus.

44. The method of Claim 43, wherein each of rings A and B is optionally and independently substituted with one or more substituents selected from the group consisting of halogen, Ci-io alkyl, C_{2-I 0} alkenyl, C_2-io alkynyl, amino, Cj-io alkylamino, Cj.io dialkylamino, Ci-io alkoxy, nitro, cyano, hydroxy, Cj. loalkoxycarbonyl, Cj.i₀ alkylcarbonyl, Ci-]Q haloalkoxy, (Ci.iohaloakoxy)Ci. io alkyl, Ci_io haloalkyl, phenyl, -(CH₂)_p-phenyl, -(CH₂)_p-(5-6 membered heteroaryl) and 5-6 membered heteroaryl, wherein p is 1 , 2, 3 or 4.

45. The method of Claim 44, wherein one or more substituents for said aliphatic groups represented by R¹,

R², R³ and R⁴ are each independently selected from the group consisting of halogen, Ar¹, -NO₂, -CN, -NCS, -C(O)OR¹⁰, -C(O)R¹⁰, -C(S)R¹⁰, -OC(O)R¹⁰, -C(O)N(R^{1 !})₂, -C(S)N(R¹ ')₂, -S(O)R¹², -S(O)₂R¹², -SO₃R¹², -SO₂N(R¹ ^₂, -SO₂N(R¹ ')-NR^π, -OR¹⁰, -SR¹⁰, -N(R¹ ')₂, -NR^{1 1}C(O)R¹⁰, -NR¹¹S(O)R¹², -NR¹¹C(O)OR¹², -N(R¹¹JC(O)N(R¹ ')₂, -NR¹¹SO₂N(R¹ ^₂, and -NR^{1 1}SO₂R¹²; one or more substituents for said aryl and heterocyclic groups represented by R¹, R², R³ and R⁴ are each independently selected from the group consisting of halogen,

Ak¹Ar¹, -NO₂, -CN, -NCS, -C(O)OR¹⁰, -C(O)R¹⁰, -C(S)R¹⁰, -OC(O)R¹⁰, -C(O)N(R¹ ')₂, -C(S)N(R¹ \, -S(O)R¹², -S(O)₂R¹², -SO₃R^{1 1},

-SO₂N(R¹ ')₂, -SO₂N(R^{1 !})-NR^π, -OR¹⁰, -SR¹⁰, -N(R¹ ')₂, -NR^{1 1}C(O)R¹⁰, -NR^{1 1}S(O)R¹², -NR^{1 1}C(O)OR¹², -N(R^{1 1})C(0)N(R¹¹)₂, -NR^{1 1}SO₂N(R¹ ^₂, -NR¹¹SO₂R¹², -0-[CH₂J_p-O-, -S-[CH₂],y-S- and -[CH₂]_r; and one or more substituents for said non-aromatic heterocyclic group formed from R³ and R⁴ together with the nitrogen atom to which R³ and R⁴ are attached are each independently selected from the group consisting of halogen, oxo, Q-I o alkyl, C_2-I₀ alkenyl, C_2-10 alkynyl, amino, Q-I₀ alkylamino, Q.iodialkylamino, Q.ioalkoxy, nitro, cyano, hydroxy, Q_-I0 alkoxycarbonyl, Cj_-10 alkylcarbonyl, Q.iohaloalkoxy, (Q.iohaloakoxy)Ci-io alkyl, Q.iohaloalkyl, phenyl, -(CH₂)_p-phenyl and 5-6 membered heteroaryl, wherein each R¹⁰ independently is: i) hydrogen; ii) a phenyl or a 5-6 membered heteroaryl group each optionally and independently substituted with one or more substituents selected from the group consisting of halogen, nitro, cyano, hydroxy, Cj_-6 alkyl, C_2-6 alkenyl, C_2-6 alkynyl, amino, Q_-6 alkylamino, Ci_-6 dialkylamino, d.₆ alkoxy, (Ci.6 alkoxy)Ci.₆ alkyl, Ci-δ haloalkoxy, Ci-g haloalkyl and (Ci_-6haloalkoxy)Ci_₆ alkyl; or iii) a Ci-io alkyl group optionally substituted with one or more substituents selected from the group consisting of halogen, hydroxyl, amino, Ci_-6 alkylamino, Ci_-6 dialkylamino, Ci_-6 alkoxy, nitro, cyano, Ci_-6 alkoxycarbonyl, C]_-6 alky lcarbonyl and Ci-ό haloalkoxy; and each R¹ ' independently is R¹⁰, -CO₂R¹⁰, -SO₂R¹⁰ or -C(O)R¹⁰, or -N(R )₂ taken together is an optionally substituted non-aromatic heterocyclic group; and each R¹² independently is: i) hydrogen; ii) a phenyl or a 5-6 membered heteroaryl group each optionally and independently substituted with one or more substituents selected from the group consisting of halogen, nitro, cyano, hydroxy, Ci_-6 alkyl, C_2-6 alkenyl, C₂.₆ alkynyl, amino, C].₆ alkylamino, Ci_-6 dialkylamino, Ci_{- 6} alkoxy, (Ci_-6 alkoxy)Ci_-6 alkyl, Ci_-6 haloalkoxy, Ci_-6 haloalkyl and (Ci_-6 haloalkoxy)Ci_-6 alkyl; or iii) a Ci-io alkyl group optionally substituted with one or more substituents selected from the group consisting of halogen, hydroxyl, amino, Cj_-6 alkylamino, Ci-_ό dialkylamino, Ci_-6 alkoxy, nitro, cyano, Ci-₆ alkoxycarbonyl, C).₆ alkylcarbonyl and Ci-_ό haloalkoxy; and each Ar¹ independently is a phenyl or a 5-6 membered heteroaryl group optionally and independently substituted with one or more substituents selected from the group consisting of halogen, nitro, cyano, hydroxy, Cj_-6 alkyl, C_2-6 alkenyl, C_2-6 alkynyl, amino, Ci_-6 alkylamino, Ci-δ dialkylamino, C]_-6 alkoxy, (Ci_-6 alkoxy)Ci.₆ alkyl, Ci_-6 haloalkoxy, (C]_-6 haloalkoxy)Ci_-6 alkyl and C).₆haloalkyl; each Ak independently is a Cj_-6 aliphatic group optionally substituted with one or more substituents selected from the group consisting of halogen, amino, Ci.₆ alkylamino, Ci_-6 dialkylamino, Ci_-6 alkoxy, nitro, cyano, hydroxy, Cj_-6 haloalkoxy, Ci_-6 alkoxycarbonyl, Ci_-6 alkylcarbonyl and C i-6 haloalkyl; each p' independently is 1, 2, 3 or 4; and each q' independently is 3, 4, 5 or 6.

46. The method of Claim 45, wherein R¹ is -H or an optionally substituted C_{M 0} aliphatic group.

47. The method of Claim 46, wherein:

Q is -OR² or -SR²; and each R independently is -H; a C1-C6 alkyl group optionally substituted with one or more substituents selected from the group consisting of halogen, amino, Ci_-6 alkylamino, Ci_-6 dialkylamino, Ci_-6 alkoxy, nitro, cyano, hydroxy, Ci_-6 haloalkoxy, Ci.₆ alkoxycarbonyl, Ci_-6 alkylcarbonyl and Ci_-6 haloalkyl; a phenyl group optionally substituted with one or more substituents selected from the group consisting of halogen, nitro, cyano, hydroxy, Ci_-6 alkyl, C_2-6 alkenyl, C_2-6 alkynyl, amino, C] -6 alkylamino, Ci_-6 dialkylamino, Ci_-6 alkoxy, (Ci_-6 alkoxy)Ci_-6 alkyl, Ci- β haloalkoxy, (C)_-6 haloalkoxy)C)_-6 alkyl and Ci_-6 haloalkyl; or a 5-6 membered heteroaryl group optionally substituted with one or more substituents selected from the group consisting of halogen, nitro, cyano, hydroxy, C _I-6 alkyl, C_2-6 alkenyl, C₂.₆ alkynyl, amino, Ci_-6 alkylamino, Ci_-6 dialkylamino, Ci_-6 alkoxy, (C)_-6 alkoxy)C i _-6 alkyl, C i _-6 haloalkoxy, (C i _-6 haloalkoxy)C i _₆ alkyl and C i _-6 haloalkyl.

48. The method of Claim 47, wherein each R² independently is -H or an optionally substituted C1-C6 alkyl group.

49. The method of Claim 48, wherein R¹ is -H or an optionally substituted Cl- C6 alkyl group.

50. The method of Claim 46, wherein the compound is represented by the following structural formula or a pharmaceutically acceptable salt thereof:

wherein:

R and R are each independently -H, an optionally substituted aliphatic group, or R³ and R⁴, taken together with the nitrogen atom to which RR³³ aanndd RR⁴⁴ aarree aattttaa<ched, form an optionally substituted, non-aromatic, heterocyclic ring.

51. The method of Claim 50, wherein rings A and B are optionally and independently substituted with one or more substituents selected from the group consisting of halogen, Ci-₆ alkyl, C₂-₆ alkenyl, C₂-₆ alkynyl, amino, C]_-6 alkylamino, C]._ό dialkyiamino, Ci^ alkoxy, nitro, cyano, hydroxy, C_K, alkoxycarbonyl, Ci^ alkylcarbonyl, Ci-g haloalkoxy, (Ci-_ό haloakoxy)Ci.₆ alkyl, Ci_₆ haloalkyl, phenyl and benzyl.

52. The method of Claim 51 , wherein the compound is represented by a structural formula selected from:

or a pharmaceutically acceptable salt thereof, wherein k and n arc each independently 1, 2, 3 or 4; and each of rings D and E is independently and optionally substituted .

53. The method of Claim 52, wherein R³ and R⁴ are each independently -H, an optionally substituted C1-C6 alkyl group, or R³ and R⁴, taken together with the nitrogen atom to which R³ and R⁴ are attached, form an optionally substituted, non-aromatic, 5 or 6-membercd heterocyclic ring.

54. The method of Claim 32, wherein rings D and E are optionally and independently substituted with one or more substituents selected from the group consisting of halogen, oxo, C)_-6 alkyl, amino, Cj-e alkylamino, Cj_-6 dialkylamino, Ci_₆ alkoxy, cyano, hydroxy, Ci-_δ haloalkoxy, (Ci_-6 haloakoxy)Ci_-6 alkyl, Ci^ haloalkyl, phenyl and benzyl,

55. The method of Claim 54, wherein k and n are each independently 1 or 2.

56. The method of Claim 55, wherein rings A and B are optionally substituted with one or more substituents selected from the group consisting of halogen, Ci-6 alkyl, amino, C i.₆ alky 1 amino, Ci_-6 dialkylamino, Ci^ alkoxy, nitro, cyano, hydroxy, Q-ό haloalkoxy, (Ci_-6 haloakoxy)Cj.₆ alkyl and Ci_-6 haloalkyl.

57. The method of Claim 56, wherein each of rings D and E is unsubstituted.

58. The method of Claim 57, wherein R³ and R⁴ are each independently -H or Cl-C6 alkyl.

59. The method of Claim 51 , wherein the compound is represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein j is 1, 2, 3 or 4; and ring F is optionally substituted.

60. The method of Claim 59, wherein ring F is optionally substituted with one or more substituents selected from the group consisting of halogen, oxo, Ci_-6 alkyl, amino, Ci-ό alkylamino, Ci_-6 dialkylamino, Ci.g alkoxy, cyano, hydroxy, Ci_-6 haloalkoxy, (Ci_-6 haloakoxy)C).6 alkyl, C)_-6 haloalkyl, phenyl and benzyl.

61. The method of Claim 60, wherein R¹ is -H or C 1 -C6 alkyl.

62. The method of Claim 61, wherein j is 1 or 2.

63. The method of Claim 62, wherein rings A and B are optionally substituted with one or more substituents selected from the group consisting of halogen, C)_-6 alkyl, amino, C].₆ alkylamino, Ci_-6 dialkylamino, Ci_-6 alkoxy, nitro, cyano, hydroxy, Ci.₆ haloalkoxy, (Ci_-6 haloakoxy)C I_-6 alkyl and Ci_-6 haloalkyl.

64. The method of Claim 63, wherein ring F is unsubstituted.