Patent Application
20100075993
1. Field of Invention
This invention relates to the field of antiviral compounds and compositions for the treatment against flaviviral infections. More specifically, it relates to novel flavivirus replication inhibitors and pharmaceutical compositions and the use thereof to treat disorders caused by West Nile virus such as viral encephalitis, and the like, and other emerging flaviviruses, such as, for example, JEV, SLEV, AV, KV, JV, CV, YV, TBEV, DENV-1, DENV-2, DENV-3, DENV-4, YFV and MVEV.
2. Description of Related Art
West Nile virus (WNV) is a mosquito-borne virus that has been introduced to the U.S. in 1999 (1, 2, 10). Since the initial outbreak, there have been cases reported in all but two states in the U.S. WNV has increasingly become a public health threat, causing hundreds of deaths and tens of thousands of infections (7). Although there has been progress in vaccine development to prevent WNV encephalitis in humans (12), there is still no effective vaccine or antiviral drug therapy (7). Currently, the only available treatment is supportive, and the only existing means of prevention is mosquito control, which is also of limited success. It is also considered to be an agent of bioterrorism concern (6), and therefore, safe and effective antiviral drugs to treat WNV infection are urgently needed.
WNV is a positive, single stranded RNA virus (4). It belongs to the Flaviviridae family, and Flavivirus genus. Many flaviviruses are significant human pathogens. In addition to WNV, this flavivirus sero-complex includes Japanese encephalitis virus (JEV), St. Louis encephalitis (SLEV), Alfuy virus (AV), Koutango virus (KV), Kunjin virus (JV), Cacipacore virus (CV), Yaounde virus (YV), and Murray Valley encephalitis virus (MVEV). The Flaviviridae family also includes the Tick-borne encephalitis virus (TBEV), Dengue virus (including the four serotypes of: DENV-1, DENV-2, DENV-3, and DENV-4), and the family prototype, Yellow Fever virus (YFV).
Flaviviruses are the most significant group of arthropod-transmitted viruses in terms of global morbidity and mortality. A combined toll of hundreds of millions of infections around the world annually coupled with the lack of sustained mosquito control measures, has distributed flaviviruses throughout the tropics, subtropics, and temperate areas. As a result, over half the world's population is at risk for flaviviral infection. Further, modern jet travel and human migration have raised the potential for global spread of these pathogens.
Strains of WNV are categorized into two different phylogenetic lineages, namely, lineage I and II, which share 75% nucleotide sequence identity (Lanciotti, R et al, (2002) Virology 298:96-105). Lineage I strains have been isolated from human and equine epidemic outbreaks from around the world and constitute the main form of human pathogen. Sequence analysis indicates that the current epidemic strain in North America belongs to lineage I. Lineage II strains are rarely isolated from humans and are geographically restricted primarily to sub-Saharan Africa and Madagascar. The differences in disease patterns of lineage I and II strains are postulated to be the result of differences in vector competence (host compatibility), virulence, and transmission cycles of the strains, as well as, host immunity (Beasley, D. W. C. et al, (2001) International Conference on the West Nile Virus, New York Academy of Science Poster Section 1:5). Sequence analysis showed that the strain in North America is closely related to other human epidemic strains isolated from Israel, Romania, Russia, and France, all of which belong to lineage I (Lanciotti, R. et al. (1999) Science 286:2333-2337).
The flavivirus genome, including the genome of WNV, is a single positive-sense RNA of approximately 10,500 nucleotides containing short 5′ and 3′ untranslated regions (UTR), a single long open reading frame (ORF), a 5′ cap region, and a non-polyadenylated 3′ terminus. The entire genome is transcribed as a single polycistronic messenger RNA molecule, which is then translated as a polyprotein. Individual proteins are subsequently produced by proteolytic processing of the polyprotein, which is directed by viral and host cell proteases (Chambers, T. J. et al, (1990) Ann. Rev. Microbiol. 44: 649-688; Lindenbach, B. D. and C. M. Rice, (2001) In D. M. Knipe and P. M. Howley (ed), Fields virology, 4.sup.th ed., vol. 1. Lippincott Williams & Wilkins, Philadelphia, Pa.).
During the replication cycle of flaviviruses, especially WNV, synthesis of positive and negative (hereafter referred to as plus (+) and minus (−), respectively) sense RNAs is asymmetric. In the case of WNV, plus-sense RNAs are produced in 10- to 100-fold excess over minus-sense RNA. Regulatory sequences in the 3′ UTR are believed to function as a promoter for initiation of minus-strand RNA synthesis. Deletion of this region ablates viral infectivity (Brinton, M. A. et al, (1986) Virology 162: 290-299; Proutski, V., et al (1997) Nucleic Acids Res. 25: 1194-1202; Rauscher, S., et al (1997) RNA 3: 779-791).
WVN genome is 12 kilobases in length and has a 5′ and 3′ non-translated region (NTR). The coding sequences specify a single polyprotein, which is proteolytically processed into approximately a dozen functional proteins by both viral and cellular proteases (5). The genes for structural Proteins, namely capsid (C), membrane (M; which exists in cells as its precursor, prM), and envelope (E) are located in the 5′ region of the genome, where those for the nonstructural proteins (NS), namely, NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5 (5) are located at the 3′ portion of the genome. WNV can infect many cell types and produce cytopathic plaques. However, due to the highly infectious nature, infections must be carried out in BL3 labs, limiting the use of the plaque assay to screen large number of compounds.
The development of therapeutic drugs and/or vaccines to treat and/or immunize against WNV and other flavivirus infections is urgently needed and of great importance to global public health. To achieve this goal, high-throughput screening assays were developed to facilitate the identification of novel chemotherapeutics effective against flaviviruses or vaccines capable of establishing a protective immune response to flaviviruses (see U.S. Patent Application Publication No. 2005/0058987 to Shi et al.). Two general strategies to be adapted for the screening and identification of novel chemotherapeutic antiflaviviral compounds and/or vaccines are based on biochemical and genetic approaches.
Assays for screening antiviral compounds that are based on biochemical approaches typically involve testing compounds for activities that limit or inhibit viral enzymes or proteins that are essential for viral propagation. For example, NS3, which has protease, helicase and NTPase activity, and NS5, which has an RNA-dependent RNA polymerase and methyltransferase activity, are key components of viral replication complex and thus, are ideal targets for antiviral screening. Further, three-dimensional structures of viral proteins, if available, can afford the possibility for rational design of drugs that will inhibit their activity, i.e., designing drugs based on the knowledge of the structure and shape of the active sites of the protein. For example, the crystal structures of the DENV NS3 protease domain and NS5 cap methyltransferase fragment have been solved and thus, the possibility of rationally designing small molecules to inhibit the active sites of NS3 and NS5 is feasible. Although biochemical approaches are capable of identifying potential viral inhibitors, they are limited in their overall efficiency since only a single enzyme or protein can be tested for any potential assay. Thus, individual assays would be required to screen for inhibitors of each given viral target protein.
In contrast, assays utilizing a genetic approach, which are usually cell-based, offer a number of advantages over biochemical approaches. One major advantage of a genetic approach based assay is that multiple viral protein targets can be analyzed simultaneously. A second major advantage is that, since genetic assays involve the use of living cells and the uptake of compounds therein, the screening assay is administered in a more authentic therapeutic environment. Accordingly, inhibitors identified through cell-based assays typically have a higher success rate in subsequent animal experiments.
A cell-based assay available for screening for flaviviral inhibitors involves the infection of cultured cells with virus and the subsequent monitoring for potential inhibition in the presence of a potential inhibitor through observation or quantification of cytopathic effects (J. D. Money et al., Antiviral Res (2002) 55:107-116; 1. Jordan, J. Infect. Dis. (2000) 182:1214-1217) or quantification of viral RNA by reverse transcriptase (RT)-PCR (S. F. Wu, J. Virol. (2002) 76:3596-3604). These assays are highly labor-intensive and impossible to use when screening compound libraries in large quantities.
Genetic high-throughput cell-based screening assays for the rapid screening and identification of potential inhibitors from compound libraries utilizing cDNA clones of RNA viruses are preferred screening tools for identifying potential inhibitors.
For example, two kinds of reverse genetics systems, full-length infectious cDNA clones and replicons, have been developed for a number of flaviviruses (A. A. Khromykh, et al., J. Virol. (1997) 71:1497-1505; M. S. Campbell, et at, Virol. (2000) 269:225-237; R. J. Hurrelbrink, et al., J. Gen. Virol. (1999) 80:3115-3125; M. Kapoor, et at, Gene (1995) 162:175-180; A. A. Khromykh et al., J. Virol. (1994) 68:4580-4588; C. J. Lai et al., Proc. Natl. Acad. Sci. U.S.A. (1991) 88:5139-5143; C. W. Mandl et al., J. Gen. Virol. (1997) 78:1049-1057; C. M. Rice et al., Science (1985) 229:726-733; H. Sumiyoshi et al., J. Virol. (1992) 66:5425-5431; S. Polo et. al., J. Virol. (1997) 71:5366-5374), including lineage II WNV (V. F. Yamshchikov et al., Virology (2001) 281:294-304). Reporter genes can be engineered into the reverse genetics systems to allow for the monitoring of viral replication levels in the presence of potential inhibitors.
U.S. Patent Application Publication No. 2005/0058987 to Shi et al. describes high-throughput cell-based assays for the rapid screening and identification of potential inhibitors from compound libraries utilizing a reverse genetics system developed for lineage I WNV cDNA clone and lineage I WNV replicon.
WNV subgenomic RNAs capable of replicating within cells (replicons) have been reported. (15, 17). The replicon RNA genome typically contains the 5′ Nontranslated region (5′ NTR), a portion of the Core coding region, a polyprotein encoding NS1 through NS5, and the 3′ NTR. Like replication of the WNV genome (reviewed in reference (4)), in the replicon cells, the viral RNA dependent RNA polymerase, NS5B, in conjunction with other viral nonstructural proteins and possibly cell factors (3), synthesize a minus strand RNA from the replicon subgenomic RNA template. The minus strand RNA in turn serves as templates for the synthesis of new genomic and message RNAs. Although data from studies of Kunjin virus suggest that both plus and minus strand RNA synthesis can occur in the absence of protein synthesis once the replication cycle establishes, viral protein synthesis is a prerequisite for replication of nascent RNAs (9). In addition to a selectable marker, neomycin phosphotransferaser gene, which is used for selection of the stable cell line, a luciferase reporter gene was also inserted into the RNA with its translation driven by the EMCV IRES (15). The expression of the reporter gene depends on the replication of the replicon RNA and can be easily monitored for identification of antiviral compounds (II).
For the purposes of drug screening it is preferable to use human epidemic-causing lineage I strains for assay setup to ensure that the identified compounds have a direct relevance to human disease.
Effective chemotherapeutics to treat WNV and other flaviviruses, known and emerging, are urgently needed. Although a limited number of inhibitors of flaviviruses have been identified, many of these have severe side effects, are not specific to flaviviruses, and are not known to be clinically effective and/or useful. For example, recent evidence suggested the use of nucleoside analogs as potential inhibitors of flaviviruses. Specific examples include inhibitors of orotidine monophosphate decarboxylase, inosine monophosphate dehydrogenase, and CTP synthetase. Although it appeared that these inhibitors may have been effective in virus infected Vero cells, their effectiveness in humans or animals (i.e., in vivo) is not known. Additionally, as these nucleoside analogs are broad-spectrum inhibitors of purine and pyrimidine biosynthesis, the occurrence of side effects and lack of flaviviral specificity would further limit their usefulness in a clinical setting.
Another nucleoside analog, the drug Ribavirin, was found to have some activity against WNV in vitro when administered in combination with interferon alpha-2b. However, the drug combination has not been shown to be effective in humans. Similarly, inhibitors to other protein activities of the viral genome, such as the helicase and protease activities encoded by NS3, have been explored; however, their clinical significance is unknown since their anti-WNV activities have not been tested in vivo. Finally, inhibitors of viral glycoprotein processing have been studied, but the prevalence of side effects due to inhibition of N-linked glycosylation, as well as difficulty in achieving therapeutic serum concentration levels, limit the usefulness of this type of compound. Thus, although there are a small number of known inhibitors for flaviviruses, none have been shown to be effective in humans. Accordingly, novel anti-flavivirus chemotherapies and/or improvements in the effectiveness, specificity, and clinical utility of known flavivirus chemotherapies are needed.
U.S. Application Publication 2006/0040958 to Guzi et al. describes pyrazolo[1,5-a]pyrimidine compounds as inhibitors of cyclin dependent kinases amd methods of making such compounds. Various pyrazolopyrimidines amd methods of making thereof are known in the art. WO92/18504, WO02/50079, WO95/35298, WO02/40485, EP94304104.6, EP0628559 (equivalent to U.S. Pat. Nos. 5,602,136, 5,602,137 and 5,571,813), U.S. Pat. No. 6,383,790, Chem. Pharm. Bull., (1999) 47 928, J. Med. Chem., (1977) 20, 296, J. Med. Chem., (1976) 19 517 and Chem. Pharm. Bull., (1962) 10 620 disclose various pyrazolopyrimidines.
WO01/92282 to Sommadossi et al. describes nucleosides for the treatment of a host infected with a flavivirus or pestivirus infection.
U.S. Pat. No. 6,812,219 to LaColla describes methods and compositions for treating flaviviruses and pestiviruses based on nucleosides.
Despite the current developments, there is a need in the art for novel flavivirus replication inhibitors, particularly, non-nucleoside based compounds.
All references cited herein are incorporated herein by reference in their entireties.
The present invention provides novel flavivirus replication inhibitors, pharmaceutical composition comprising one or more such flavivirus replication inhibitors and methods of treatment, prevention, inhibition or amelioration of one or more diseases associated with flavivirus replication using such inhibitors or pharmaceutical compositions. The replicon system used to discover flavivirus replication inhibitors of the invention is derived from a linkage I WNV isolate that have caused human infection and thus very relevant for finding an inhibitor to treat WNV infection.
In one aspect, the present invention relates to a flavivirus replication inhibitor, or pharmaceutically acceptable salts, solvates, esters or prodrugs of flavivirus replication inhibitor, wherein the flavivirus replication inhibitor is a compound of Formula (I)
wherein X, Y and R1-6 are members selected from the group consisting of H, halogen, alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl, wherein each of said alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, arylalkyl, cycloalkyl, alkoxy, heterocyclyl, heterocyclylalkyl, heteroaryl, heteroarylalkyl, CF3, OCF3, CN, and —OH, and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In a preferred embodiment, the flavivirus replication inhibitor is an inhibitor of West Nile virus replication. Preferably, the flavivirus replication inhibitor has an anti-viral activity tested in a live virus assay with 50% inhibitory concentration (IC50) less than 5 μM and 50% cytotoxic concentration (CC 50) at greater than 50 μM.
In certain embodiments, the flavivirus replication inhibitor is a compound having Formula (XIII) (also referred to herein as 18-B3)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In certain embodiments, the flavivirus replication inhibitor is a compound of Formula (XIV) (also referred to herein as 18-D2)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In certain embodiments, the flavivirus replication inhibitor is a compound of Formula (XV) (also referred to herein as 18-H5)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In certain embodiments, the flavivirus replication inhibitor is a compound of Formula (XVI) (also referred to herein as 20-E7)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In certain embodiments, the flavivirus replication inhibitor is a compound of Formula (XVII) (also referred to herein as 253-B10)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In certain embodiments, the flavivirus replication inhibitor is a compound of Formula (XVIII) (also referred to herein as 253-F8)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In certain embodiments, the flavivirus replication inhibitor is a compound of Formula (XIX) (also referred to herein as 253-F11)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In certain embodiments, the flavivirus replication inhibitor is a compound 253-G8 of Formula (XX) (also referred to herein as 253-G8)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In certain embodiments, the flavivirus replication inhibitor is a compound 253-H8 of Formula (XXI) (also referred to herein as 253-H8)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In another aspect, the present invention relates to a pharmaceutical composition comprising a pharmaceutically acceptable carrier and the compound of Formula (I).
In another aspect, the present invention relates to a process for making a pharmaceutical composition comprising combining the compound of Formula (I) and a pharmaceutically acceptable carrier.
In another aspect, the present invention relates to a method of treatment, prevention, inhibition or amelioration of one or more diseases associated with flavivirus replication in a subject in need thereof comprising administering to the subject a therapeutically effective amount of a pharmaceutical composition comprising administering to the subject a therapeutically effective amount of a pharmaceutical composition comprising the compound of Formula (I) and a pharmaceutically acceptable carrier. In certain embodiments of the method, the flavivirus caused disorder is a disorder related to a West Nile virus caused disorder.
In yet another aspect, the present invention relates to a flavivirus replication inhibitor, wherein the flavivirus replication inhibitor is a compound of Formula (II)
wherein R is a member selected from the group consisting of H, alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl, wherein each of said alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, arylalkyl, cycloalkyl, alkoxy, heterocyclyl, heterocyclylalkyl, heteroaryl, heteroarylalkyl, CF3, OCF3, CN, and —OH;
R7 is a member selected from the group consisting of H, halogen, alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroaryl alkyl, wherein each of said alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, arylalkyl, cycloalkyl, alkoxy, heterocyclyl, heterocyclylalkyl, heteroaryl, heteroarylalkyl, CF3, OCF3, CN, and —OH; and
R8-14 are members selected from the group consisting of H, alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl, wherein each of said alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, arylalkyl, cycloalkyl, alkoxy, heterocyclyl, heterocyclylalkyl, heteroaryl, heteroarylalkyl, CF3, OCF3, CN, and —OH. In a preferred embodiment, the flavivirus replication inhibitor is an inhibitor of West Nile virus replication. Preferably, the flavivirus replication inhibitor has an anti-viral activity tested in a live virus assay with 50% inhibitory concentration (IC50) less than 5 μM and 50% cytotoxic concentration (CC 50) at greater than 50 μM.
In a preferred embodiment, the flavivirus replication inhibitor is a compound 309-F6 of Formula (XI) (also referred to herein as 309-F6)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In certain embodiments, the flavivirus replication inhibitor is a compound of Formula (XII) (also referred to herein as 275-F9)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In certain embodiments, the flavivirus replication inhibitor is a compound of Formula (XXII) (also referred to herein as 310-B3)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In another aspect, the present invention relates to a pharmaceutical composition comprising a pharmaceutically acceptable carrier and the compound of Formula (II).
In certain embodiments, the pharmaceutical composition comprises the pharmaceutically acceptable carrier and the compound of Formula (XI), derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In another aspect, the present invention relates to a process for making a pharmaceutical composition comprising combining the compound of Formula (II) and a pharmaceutically acceptable carrier.
In another aspect, the present invention relates to a method of treatment, prevention, inhibition or amelioration of one or more diseases associated with flavivirus replication in a subject in need thereof comprising administering to the subject a therapeutically effective amount of a pharmaceutical composition comprising the compound of Formula (II) and a pharmaceutically acceptable carrier.
In yet another aspect, the present invention relates to a flavivirus replication inhibitor, wherein the flavivirus replication inhibitor is a compound of Formula (III)
wherein R15-27 are members selected from the group consisting of H, halogen, alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl, wherein each of said alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, arylalkyl, cycloalkyl, alkoxy, heterocyclyl, heterocyclylalkyl, heteroaryl, heteroarylalkyl, CF3, OCF3, CN, and —OH. In a preferred embodiment, the flavivirus replication inhibitor is an inhibitor of West Nile virus replication. Preferably, the flavivirus replication inhibitor has an anti-viral activity tested in a live virus assay with 50% inhibitory concentration (IC50) less than 5 μM and 50% cytotoxic concentration (CC 50) at greater than 50 μM.
In certain embodiments, the flavivirus replication inhibitor is a compound of Formula (IV) (also referred to herein as 101-G7)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In another aspect, the present invention relates to a pharmaceutical composition comprising a pharmaceutically acceptable carrier and the compound of Formula (III). In a preferred embodiment, the pharmaceutical composition comprises the pharmaceutically acceptable carrier the compound of Formula (IV), derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In another aspect, the present invention relates to a process for making a pharmaceutical composition comprising combining the compound of Formula (III) and a pharmaceutically acceptable carrier.
In another aspect, the present invention relates to a method of treatment, prevention, inhibition or amelioration of one or more diseases associated with flavivirus replication in a subject in need thereof comprising administering to the subject a therapeutically effective amount of a pharmaceutical composition comprising administering to the subject a therapeutically effective amount of a pharmaceutical composition comprising the compound of Formula (III) and a pharmaceutically acceptable carrier. In certain embodiments of the method the flavivirus caused disorder is a disorder related to a West Nile virus caused disorder.
In yet another aspect, the present invention relates to a flavivirus replication inhibitor, wherein the flavivirus replication inhibitor is at least one of
(a) a compound of Formula (V) (also referred to herein as 2-H7)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof;
(b) a compound of Formula (VI) (also referred to herein as 24-C10)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof;
(c) a compound of Formula (VII) (also referred to herein as 42-E5)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof;
(d) a compound of Formula (VIII) (also referred to herein as 50-A8)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof;
(e) a compound of Formula (IX) (also referred to herein as 63-C10)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof;
(f) a compound of Formula (X) (also referred to herein as 182-C2)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof; or
(g) a compound of Formula (XXIII) (also referred to herein as 309-F6)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
The invention will be described in conjunction with the following drawings in which like reference numerals designate like elements and wherein:
The invention provides novel flavivirus replication inhibitors of WNV other emerging flaviviruses, such as, for example, JEV, SLEV, AV, KV, JV, CV, YV, TBEV, DENV-1, DENV-2, DENV-3, DENV-4, YFV and MVEV, pharmaceutical composition comprising one or more such flavivirus replication inhibitors and methods of treatment, prevention, inhibition or amelioration of one or more diseases associated with flavivirus replication administering such inhibitors or pharmaceutical compositions.
Several classes of small molecule inhibitors of WNV replicon were discovered through high-throughput screening of a collection of more than 35, 000 compounds.
The invention will be described using 23 compounds as examples which were found to meet the criteria of selective inhibition of WNV replication and/or protein accumulation (Table 3) based on IC50 at most 10 uM and CC50 at least 10 uM.
As summarized in Table 3 below and
Compounds 331-D11 (
A preferred group of flavivirus replication inhibitors of the invention consists of parazolotrahydrothophenes (PyrozoloHTH). PyrozoloHTH compounds have a pyrozolotetrahydrophene core structure with modification at the aryl phenol ring group and the 5-position amide group. PyrozoloHTH compounds are represented by Formula (I)
wherein X, Y and R1-6 are members selected from the group consisting of H, halogen, alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl, wherein each of said alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, arylalkyl, cycloalkyl, alkoxy, heterocyclyl, heterocyclylalkyl, heteroaryl, heteroarylalkyl, CF3, OCF3, CN, and —OH.
Exemplary non-limiting compounds include 18-B3, 18-D2, 18-H5, 20-E7, 253-B10, 253-F8, 253-F11, 253-G8, and 253-H8 (
Another preferred group of the flavivirus replication inhibitors of the invention consists of pyrazolopyrimidines. Pyrazolopyrimidine compounds are represented by Formula (II)
wherein R is a member selected from the group consisting of H, alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl, wherein each of said alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, arylalkyl, cycloalkyl, alkoxy, heterocyclyl, heterocyclylalkyl, heteroaryl, heteroarylalkyl, CF3, OCF3, CN, and —OH;
R7 is a member selected from the group consisting of H, halogen, alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl, wherein each of said alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, arylalkyl, cycloalkyl, alkoxy, heterocyclyl, heterocyclyl alkyl, heteroaryl, heteroarylalkyl, CF3, OCF3, CN, and —OH; and
R8-14 are members selected from the group consisting of H, alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl, wherein each of said alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, arylalkyl, cycloalkyl, alkoxy, heterocyclyl, heterocyclylalkyl, heteroaryl, heteroarylalkyl, CF3, OCF3, CN, and —OH. In a preferred embodiment, the flavivirus replication inhibitor is an inhibitor of West Nile virus replication. Preferably, the flavivirus replication inhibitor has an anti-viral activity tested in a live virus assay with 50% inhibitory concentration (IC50) less than 5 μM and 50% cytotoxic concentration (CC 50) at greater than 50 μM.
Exemplary pyrazolopyrimidine compounds are 275-D9, 275-F9, 309-F6 and 310-B3 (
In a preferred embodiment, the flavivirus replication inhibitor is a compound 309-F6 of Formula (XI) (also referred to herein as 309-F6)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In certain embodiments, the flavivirus replication inhibitor is a compound of Formula (XII) (also referred to herein as 275-F9)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In certain embodiments, the flavivirus replication inhibitor is a compound of Formula (XXII) (also referred to herein as 310-B3)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In yet another aspect, the present invention relates to a flavivirus replication inhibitor, wherein the flavivirus replication inhibitor is a compound of Formula (III)
wherein R15-27 are members selected from the group consisting of H, halogen, alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroaryl alkyl, wherein each of said alkyl, aryl, alkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, arylalkyl, cycloalkyl, alkoxy, heterocyclyl, heterocyclylalkyl, heteroaryl, heteroarylalkyl, CF3, OCF3, CN, and —OH. In a preferred embodiment, the flavivirus replication inhibitor is an inhibitor of West Nile virus replication. Preferably, the flavivirus replication inhibitor has an anti-viral activity tested in a live virus assay with 50% inhibitory concentration (IC50) less than 5 μM and 50% cytotoxic concentration (CC 50) at greater than 50 μM.
In certain embodiments, the flavivirus replication inhibitor is a compound of Formula (IV) (also referred to herein as 101-G7)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
In yet another aspect, the present invention relates to a flavivirus replication inhibitor, wherein the flavivirus replication inhibitor is at least one of
(a) a compound of Formula (V) (also referred to herein as 2-H7)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof;
(b) a component of a structure (VI) (also referred to herein as 24-C10)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof;
(c) a compound of Formula (VII) (also referred to herein as 42-E5)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof;
(d) a compound of Formula (VIII) (also referred to herein as 50-A8)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof;
(e) a compound of Formula (IX) (also referred to herein as 63-C10)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof;
(f) a compound of Formula (X) (also referred to herein as 182-C2)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof; or
(g) a compound of Formula (XXIII) (also referred to herein as 309-F6)
and derivatives thereof and pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
Pharmaceutical Compositions
The compounds will be studied for their pharmacology kinetics and for their toxicity profile in relevant animal models as described in publicly available literature.
Thus, in another aspect, the present invention relates to a pharmaceutical composition comprising a pharmaceutically acceptable carrier and one or more of the “active” compounds flavivirus replication inhibitors described herein (e.g., compounds of Formulas (I)-(XXIII)) including pharmaceutically acceptable salts, solvates, esters or prodrugs thereof.
The pharmaceutical compositions comprising the compositions of the invention may be in a variety of conventional depot forms. These include, for example, solid, semi-solid and liquid dosage forms, such as tablets, pills, powders, liquid solutions or suspensions, liposomes, capsules, suppositories, injectable and infusible solutions. The preferred form depends upon the intended mode of administration and prophylactic application.
Such dosage forms may include pharmaceutically acceptable carriers and adjuvants which are known to those of skill in the art. These carriers and adjuvants include, for example, RtBI, ISCOM, ion exchangers, alumina, aluminum stearate, lecithin, serum proteins, such as human serum albumin, buffer substances, such as phosphates, glycine, sorbic acid, potassium sorbate, partial glyceride mixtures of saturated vegetable fatty acids, water, salts or electrolytes such as protamine sulfate, disodium hydrogen phosphate, sodium chloride, zinc salts, colloidal silica, magnesium trisilicate, polyvinyl pyrrolidone, cellulose-based substances, and polyethylene glycol. Adjuvants for topical or gel base forms may be selected from the group consisting of sodium carboxymethylcellulose, polyacrylates, polyoxyethylene-polyoxypropylene-b-lock polymers, polyethylene glycol, and wood wax alcohols.
The compositions of the invention may also include other components or be subject to other treatments during preparation to enhance their bioavailability or to improve their tolerance in patients.
In another aspect, the present invention relates to a process for making a pharmaceutical composition comprising combining one or more of the “active” compounds flavivirus replication inhibitors described herein (e.g., compounds of Formulas (I)-(XXIII)) and a pharmaceutically acceptable carrier. The term “combining” includes all aspects of combining the components, including but not limited to dissolving, admixing, dispersing, embedding and encapsulating. The term “combining” encompasses partial mixing of the components and combining the components with additional components which would serve as a layer between components such that no or substantially no immediate contact between the active components is observed.
In another aspect, the present invention relates to a method of treatment, prevention, inhibition or amelioration of one or more diseases associated with flavivirus replication in a subject in need thereof comprising administering to the subject a therapeutically effective amount of a pharmaceutical composition comprising one or more of the “active” compounds flavivirus replication inhibitors described herein (e.g., compounds of Formulas (I)-(XXIII)) and a pharmaceutically acceptable carrier. treatment, prevention, inhibition or amelioration of one or more diseases associated with flavivirus replication including administering one or more such inhibitors or pharmaceutical compositions.
Any pharmaceutically acceptable dosage route, including parenteral, intravenous, intramuscular, intralesional or subcutaneous injection, may be used to administer the compositions of the invention. For example, the composition may be administered to the patient in any pharmaceutically acceptable dosage form including those which may be administered to a patient intravenously as bolus or by continued infusion over a period of hours, days, weeks or months, intramuscularly—including paravertebrally and periarticularly—subcutaneously, intracutaneously, intra-articularly, intrasynovially, intrathecally, intralesionally, periostally or by oral or topical routes. Preferably, the compositions of the invention are in the form of a unit dose and will usually be administered to the patient orally.
The pharmaceutical compositions comprising the compositions of the invention or derivatives or modifications thereof may also be administered to any animal, including, but not limited to, horses, cattle, monkeys, birds, dogs, cats, ferrets, rodents, squirrels, and rabbits to provide a protective immune response therein against a flavivirus, e.g., WNV, DENV, or any other known or emerging flavivirus, and/or to treat or limit the lateral passage of infection by a flavivirus to humans. For example, the pharmaceutical compositions comprising the compositions of the invention can be combined with animal feed stock and/or water provisions, dog food, cat food, bird food, or rodent food. One of skill in the art will understand this method of administration is sometimes referred to as “bait dropping,” in which the pharmaceutical composition is included within the food and/or water of the organism to be treated.
Screening Method
Ten micromolar concentrations of a selected compound were incubated with BHK 26.5 cells expressing luciferase whose activity is dependent upon WNV replicon replication (
Primary “hits” were validated as selective for WNV (as opposed to inhibitory of luciferase) in a second assay, in which compound was tested for the ability to reduce the amount of WNV RNA and protein production.
The mechanisms of action for these “hits” are being investigated. Whether the compounds are targeting a viral protein or a cellular process that is involved is not known. Inventors are developing virus resistance to the most potent “hits” in order to find out whether a viral protein in the WNV RNA replication complex is involved. Without being bound by a specific theory, based on the western blot data (
Although the “hits” clearly demonstrate ability to inhibit the WNV replication-dependent luciferase activity and reduce WNV viral protein accumulation and viral RNA levels in replicon cells, the compounds need to be re-synthesized and re-tested. If the re-synthesized compounds do not inhibit, some contaminating chemical or modified products in the compound library must exist. In that case, an analysis should be performed to determine the nature of this component. Compound 101-G7 was re-synthesized and its activity was confirmed as described below.
Several small molecules, in particular, nucleoside analogs have been reported to be active in controlling flavivirus infections (13), supporting the contention that antiviral drugs could be useful in combating the emerging public health threat produced by WNV infection. The high throughput screen “hits” identified by inventors clearly indicate the potential of developing such small molecule non-nucleoside inhibitors. These hits, though not as potent, can serve as the starting point for rational design of more potent WNV inhibitors. Furthermore, the “hits” can be useful research tools in dissecting the molecular mechanisms of the WNV replication and viral host interaction.
High Throughput Assay
To find the best condition for a high throughput assay, among the many variables, cell density, DMSO concentration, and the effect of freeze/thaw cycle of cells on the assay were considered. First, BHK 26.5 cells were seeded 24 hours before the assay at a density ranging from 1500 to 30,000 cells per well. As shown in
Minimal assay signal variation and consistent high signal to background ratio is key to the success of an HTS assay. Z', a statistical measurement of the distance between the standard deviations for the signal versus the noise of an assay was determined by treating multiple samples with mycophenolic acid (MPA), a known albeit nonspecific, WNV inhibitor. Briefly, 40 wells of a 96 well plate were treated with 2.5% MPA in 1% final DMSO, and 40 wells were treated with 1% DMSO only. After 24 hours, the luminescence was measured. The Z′ was calculated by the equation: 1−(3×SDDMSO+3×SDMPA)/MeanDMSO−MeanMPA). The Z′ is approximately 0.5, indicating that the assay is reasonably reliable. The assay consistently produced a noise to background ration of around 8 to 1.
The HTS strategy follows the flowchart outlined in
Eliminating Luciferase Enzyme Inhibitors
Although the initial HTS and the repeat assays have identified a number of compounds capable of reducing the luciferase activity produced in the WNV replicon BHK 26.5 cell line. It is conceivable that some of these inhibitors could have inhibited the luciferase enzyme itself rather than the WNV viral replication. To rule out this possibility, the identified compounds were tested in an in vitro luciferase enzyme assay by incubating the compounds with cell lysates prepared from the WNV replicon cell. Under such conditions, replication of WNV does not contribute to luciferase activity and inhibition of the luciferase enzyme can be identified.
IC50 Determination of the “Hit” Compounds
To quantify and rank the activity of the 23 remaining compound “hits”, a serial dilution of each compound was incubated with WNV replicon cells to determine the concentration that inhibits 50% of the luciferase readout (IC50s).
Confirmation of the WNV Inhibitor Compounds
Although it is reassuring that multiple tests have yielded similar positive results, the ability of the compounds to inhibit WNV replication was further assessed in secondary assays. In the western blot analysis shown in
To confirm that the compounds can indeed inhibit WNV RNA replication, the WNV RNA level in the replicon cells treated with compounds by Northern blot analysis. Several hit compounds, 18-B3, 275-F9, 275-D9, 52-F2 and MPA were selected to treat the BHK 26.5 cells at 10 μM.
Although the compounds selected from the WNV replicon screen were shown to reduce replicon protein and RNA synthesis, the data from the Western and Northern blots also showed that these compounds had limited potency indicating that they might require further improvement by chemical modification to become potent virus inhibitors. Several of these original compounds selected from the WNV replicon based screen were evaluated in an antiviral assay against WNV live virus.
Additional confirmation was obtained for the compound 101-G7. Specifically, inventors re-synthesized 101-G7 through conventional chemistry. This is to ascertain that the activity detected from the compound library is due to the specified chemical rather than some contaminating or breakdown products present in the library. After 101-G7 was synthesized, it was re-tested in the WNV replicon cells and in the WNV infection assay.
The toxicity of 101-G7 was also measured by MTT assay and CC50 was calculated. 40 μM is highest concentration used.
Cells and Media
The WNV sequence was an infectious strain derived from an immuncomprised patient. The cDNA and WNV replicon construction was described in Rossi et al. (15). The WNV replicon (
Chemical Library
The chemical library includes selected compounds from the collections of Asinex Inc. (Moscow, Russia), Chembridge Inc. (San Diego, Calif.) and Maybridge Inc. (Cornwall, UK). The compounds were selected by computational means for diversity, solubility and drug-like qualities, eliminating highly reactive groups and species known to exhibit non-specific biological effects, and exhibiting an average molecular weight of approximately 350 Daltons. The original compound library stock plates (“mother” plates) are comprised of wells containing compounds corresponding to 80 wells per 96 well plates, specifically columns 2 to 11, rows A-H. Each compound was dissolved in tissue-culture grade dimethylsulfoxide (DMSO) at an average concentration of 10 mM. Dilution (“daughter”) plates have been produced by replica-plating of the mother plates in DMSO to give an average concentration of 1 mM. Both mother and daughter plates were sealed with plastic film and stored at ±20° C.
Antiviral treatment of replicon-expressing cells and high throughput assay.
Replicon-harboring cells were plated 96-well plates at 10,000 cells per well in MEM plus 3% FBS. 24 hours after plating, compounds were added to the wells by a Robotic liquid handler (Biomek NX) to a final concentration of 10 μM and 1% DMSO. For each 96 well plate, A1 to A8 were left open, H1 to H4 contained 1% DMSO, H5-H8 contained Mycophenolic acid (Sigma-Aldrich, St. Louis, Mo.), which was included as positive controls. After 24 hours of treatment, the media were removed and the luciferase activity expressed in the replicon cells was quantified. When cyto-toxicity was measured, duplicate 96 well plates were plated with BHK 26.5 replicon cells. One plate was used for luciferase assay and one plate was used for measuring toxicity using MTT assay.
Luciferase Assay
Luciferase assay was performed by using the STEADY GLO reagent (Promega Corp. Madison, Wis.) according to the manufacturer's recommendation with slight modifications. Briefly, the culture media from the 96 wells were removed by dumping on paper towels.
100 μl of a 1:1 mixture of luciferase regent and culture media were added to the plate. After 5-minute incubation, the luminescence was read on a TOPCOUNT (PerkinElmer, Wellesley, Mass.).
Western Blot Analysis
Total cell lysates from replicon cells were harvested from replicon cells in 1×SDS sample buffer. The lysates were heated at 70° C. for 10 min in the presence of DTT before electrophoresis on a 10% Tris-glycine SDS polyacrylamide gel (Invitrogen) in 1× Tris-glycine buffer. The protein was transferred to PVDF (Invitrogen) membrane. Following the transfer, the membrane was rinsed once with TBS containing 0.5% Tween-20 (TBS-Tween) and blocked in TBS-Tween containing 5% non-fat milk for 1 h. After washing with PBS-Tween, the membrane was incubated with the primary WNV antibody (15) at 1:3000 dilutions for 1 h at 25° C. Prior to incubation with HRP conjugated-mouset IgG secondary antibody (Amersham, Life Science, Piscataway, N.J.) diluted 1:5000, the blot was washed in PBS-Tween. Following the secondary antibody incubation, the blot was washed again and treated with Super Signal Chemiluminescent Reagent (Pierce) according to the manufacturer's protocol and exposed to X-ray film. For controls, the blots were stripped and re-probed with an antibody to beta-actin (Chemicon), which was detected with a goat anti-mouse horseradish peroxidase conjugate.
MTT Assays
Compound toxicity was determined by MTT assay. For the MTT assay, the cell medium was removed and the monolayers were incubated with 100 μl/well of 0.5 mg/ml MTT for 6 h at 37° C. The MTT solution was then aspirated and 100 μl/well of the 10% SDS (in 0.01N HCl) was added, followed by spectrophotometric quantitation (570 nm) of the insoluble MIT reaction product.
Northern Blot Analysis
Total cellular RNA was extracted by using the RNEASY kit (Qiagen NV, Netherlands). Northern blot analysis was done according to the protocol of Gu et al. 2002 (8). Briefly, 5 μg total RNA was electrophoresed through a 1.0% agarose gel containing 2.2M formaldehyde, transferred to a nylon membrane and immobilized by UV cross-linking (Stratagene, La Jolla, Calif.). After pre-hybridization in 5 ml of QuickHyb (Amersham, Piscataway, N.J. GE Healthcare, Giles, UK), [2P] dCTP-labeled probe made by random primer labeling of a 2.7 kb NS5 DNA fragment and a human beta-actin DNA at 65° C. The membrane was washed twice in 2×SSC/0.1% SDS for 10 min at room temperature and twice in 0.1×SSC/0.1% SDS for 15 min at 68° C. Membranes were exposed to Molecular Imager FX phosphoimager (BioRad, Hercules, Calif.) and the radiographic signals were collected and quantitated.
WNV Yield Reduction Assay
To measure activity against live WNV, BHK cells were plated in 96-well plates at a concentration of 12,000 cells/well. One day later the cells were infected with WNV for 1 h at an MOI of 0.05. The cells were then washed once and re-fed with fresh DMEM containing dilutions of the test compound. Plates were then incubated at 37° C. for 48 h, the supernatant collected and the WNV produced titered. For virus titration, Vero cells were plated in 96-well plates at 8000 cells/well and incubated overnight. The Vero cell monolayer were then infected for 1 h with various dilutions of the WNV supernatant, overlaid with media containing 0.6% tragacanth (ICN, CA) and incubated at 37° C. for 48 h. The culture media was then aspirated; the plate was rinsed, air-dried, and fixed with 50 μl/well acetone/methanol (50:50). Viral foci were detected for enumeration by immunostaining as described previously (15).
Methods of Making Compounds of the Invention
The compounds of Table 3 are available from the collections of Asinex Inc. (Moscow, Russia), Chembridge Inc. (San Diego, Calif.) and Maybridge Inc. (Cornwall, UK).
The flavivirus replication inhibitors of the invention and derivatives thereof can be prepared by methods and techniques known in the art. As can be appreciated by those skilled in the art, modifications and different substitutions of various groups in the compounds of the invention can be performed by known methods and techniques as for example, described in Strategic Applications of Named Reactions in Organic Synthesis: Background and Detailed Mechanisms by Laszlo Kurti ((2005); Academic Press; ISBN: 0124297854), U.S. Application Publication 2006/0040958 to Guzi et al., WO92/18504, WO02/50079, WO95/35298, WO02/40485, EP94304104.6, EP0628559 (equivalent to U.S. Pat. Nos. 5,602,136, 5,602,137 and 5,571,813), U.S. Pat. No. 6,383,790, Chem. Pharm. Bull., (1999) 47 928, J. Med. Chem., (1977) 20, 296, J. Med. Chem., (1976) 19 517 and Chem. Pharm. Bull., (1962) 10 620, WO01/92282 to Sommadossi et al., U.S. Pat. No. 6,812,219 to LaColla, which are incorporated herein in their entireties.
“Alkyl” means an aliphatic hydrocarbon group which may be straight or branched and comprising about 1 to about 20 carbon atoms in the chain. Preferred alkyl groups contain about 1 to about 12 carbon atoms in the chain. More preferred alkyl groups contain about 1 to about 6 carbon atoms in the chain. Branched means that one or more lower alkyl groups such as methyl, ethyl or propyl, are attached to a linear alkyl chain. “Lower alkyl” means a group having about 1 to about 6 carbon atoms in the chain which may be straight or branched. “Alkyl” may be unsubstituted or optionally substituted by one or more substituents which may be the same or different, each substituent being independently selected from the group consisting of halo, alkyl, aryl, cycloalkyl, cyano, hydroxy, alkoxy, alkylthio, amino, —NH(alkyl), —NH(cycloalkyl), —N(alkyl)2, carboxy and —C(O)O-alkyl. Non-limiting examples of suitable alkyl groups include methyl, ethyl, n-propyl, isopropyl and t-butyl.
“Alkenyl” means an aliphatic hydrocarbon group containing at least one carbon-carbon double bond and which may be straight or branched and comprising about 2 to about 15 carbon atoms in the chain. Preferred alkenyl groups have about 2 to about 12 carbon atoms in the chain; and more preferably about 2 to about 6 carbon atoms in the chain. Branched means that one or more lower alkyl groups such as methyl, ethyl or propyl, are attached to a linear alkenyl chain. “Lower alkenyl” means about 2 to about 6 carbon atoms in the chain which may be straight or branched. “Alkenyl” may be unsubstituted or optionally substituted by one or more substituents which may be the same or different, each substituent being independently selected from the group consisting of halo, alkyl. aryl, cycloalkyl, cyano, alkoxy and S(alkyl). Non-limiting examples of suitable alkenyl groups include ethenyl, propenyl, n-butenyl, 3-methylbut-2-enyl, n-pentenyl, octenyl and decenyl.
“Alkylene” means a difunctional group obtained by removal of a hydrogen atom from an alkyl group that is defined above. Non-limiting examples of alkylene include methylene, ethylene and propylene.
“Alkynyl” means an aliphatic hydrocarbon group containing at least one carbon-carbon triple bond and which may be straight or branched and comprising about 2 to about 15 carbon atoms in the chain. Preferred alkynyl groups have about 2 to about 12 carbon atoms in the chain; and more preferably about 2 to about 4 carbon atoms in the chain. Branched means that one or more lower alkyl groups such as methyl, ethyl or propyl, are attached to a linear alkynyl chain. “Lower alkynyl” means about 2 to about 6 carbon atoms in the chain which may be straight or branched. Non-limiting examples of suitable alkynyl groups include ethynyl, propynyl, 2-butynyl and 3-methylbutynyl. “Alkynyl” may be unsubstituted or optionally substituted by one or more substituents which may be the same or different, each substituent being independently selected from the group consisting of alkyl, aryl and cycloalkyl.
“Aryl” means an aromatic monocyclic or multicyclic ring system comprising about 6 to about 14 carbon atoms, preferably about 6 to about 10 carbon atoms. The aryl group can be optionally substituted with one or more “ring system substituents” which may be the same or different, and are as defined herein. Non-limiting examples of suitable aryl groups include phenyl and naphthyl.
“Heteroaryl” means an aromatic monocyclic or multicyclic ring system comprising about 5 to about 14 ring atoms, preferably about 5 to about 10 ring atoms, in which one or more of the ring atoms is an element other than carbon, for example nitrogen, oxygen or sulfur, alone or in combination. Preferred heteroaryls contain about 5 to about 6 ring atoms. The “heteroaryl” can be optionally substituted by one or more “ring system substituents” which may be the same or different, and are as defined herein. The prefix aza, oxa or thia before the heteroaryl root name means that at least a nitrogen, oxygen or sulfur atom respectively, is present as a ring atom. A nitrogen atom of a heteroaryl can be optionally oxidized to the corresponding N-oxide. Non-limiting examples of suitable heteroaryls include pyridyl, pyrazinyl, furanyl, thienyl, pyrimidinyl, pyridone (including N-substituted pyridones), isoxazolyl, isothiazolyl, oxazolyl, thiazolyl, pyrazolyl, furazanyl, pyrrolyl, pyrazolyl, triazolyl, 1,2,4-thiadiazolyl, pyrazinyl, pyridazinyl, quinoxalinyl, phthalazinyl, oxindolyl, imidazo[1,2-a]pyridinyl, imidazo[2,1-b]thiazolyl, benzofurazanyl, indolyl, azaindolyl, benzimidazolyl, benzothienyl, quinolinyl, imidazolyl, thienopyridyl, quinazolinyl, thienopyrimidyl, pyrrolopyridyl, imidazopyridyl, isoquinolinyl, benzoazaindolyl, 1,2,4-triazinyl, benzothiazolyl and the like. The term “heteroaryl” also refers to partially saturated heteroaryl moieties such as, for example, tetrahydroisoquinolyl, tetrahydroquinolyl and the like.
“Aralkyl” or “arylalkyl” means an aryl-alkyl-group in which the aryl and alkyl are as previously described. Preferred aralkyls comprise a lower alkyl group. Non-limiting examples of suitable aralkyl groups include benzyl, 2-phenethyl and naphthalenylmethyl. The bond to the parent moiety is through the alkyl.
“Alkylaryl” means an alkyl-aryl-group in which the alkyl and aryl are as previously described. Preferred alkylaryls comprise a lower alkyl group. Non-limiting example of a suitable alkylaryl group is tolyl. The bond to the parent moiety is through the aryl.
“Cycloalkyl” means a non-aromatic mono- or multicyclic ring system comprising about 3 to about 10 carbon atoms, preferably about 5 to about 10 carbon atoms. Preferred cycloalkyl rings contain about 5 to about 7 ring atoms. The cycloalkyl can be optionally substituted with one or more “ring system substituents” which may be the same or different, and are as defined above. Non-limiting examples of suitable monocyclic cycloalkyls include cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl and the like. Non-limiting examples of suitable multicyclic cycloalkyls include 1-decalinyl, norbornyl, adamantyl and the like.
“Cycloalkylalkyl” means a cycloalkyl moiety as defined above linked via an alkyl moiety (defined above) to a parent core. Non-limiting examples of suitable cycloalkylalkyls include cyclohexylmethyl, adamantylmethyl and the like.
“Cycloalkenyl” means a non-aromatic mono or multicyclic ring system comprising about 3 to about 10 carbon atoms, preferably about 5 to about 10 carbon atoms which contains at least one carbon-carbon double bond. Preferred cycloalkenyl rings contain about 5 to about 7 ring atoms. The cycloalkenyl can be optionally substituted with one or more “ring system substituents” which may be the same or different, and are as defined above. Non-limiting examples of suitable monocyclic cycloalkenyls include cyclopentenyl, cyclohexenyl, cyclohepta-1,3-dienyl, and the like. Non-limiting example of a suitable multicyclic cycloalkenyl is norbornylenyl.
“Cycloalkenylalkyl” means a cycloalkenyl moiety as defined above linked via an alkyl moiety (defined above) to a parent core. Non-limiting examples of suitable cycloalkenylalkyls include cyclopentenylmethyl, cyclohexenylmethyl and the like.
“Halogen” means fluorine, chlorine, bromine, or iodine. Preferred are fluorine, chlorine and bromine.
“Ring system substituent” means a substituent attached to an aromatic or non-aromatic ring system which, for example, replaces an available hydrogen group on the ring system. Ring system substituents may be the same or different, each being independently selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, heteroaryl, aralkyl, alkylaryl, heteroaralkyl, heteroarylalkenyl, heteroarylalkynyl, alkylheteroaryl, hydroxy, hydroxyalkyl, alkoxy, aryloxy, aralkoxy, acyl, aroyl, halo, nitro, cyano, carboxy, alkoxycarbonyl, aryloxycarbonyl, aralkoxycarbonyl, alkylsulfonyl, arylsulfonyl, heteroarylsulfonyl, alkylthio, arylthio, heteroarylthio, aralkylthio, heteroaralkylthio, cycloalkyl, heterocyclyl, and others as described in U.S. Application Publication 2006/0040958 to Guzi et al.
“Heteroarylalkyl” means a heteroaryl moiety as defined above linked via an alkyl moiety (defined above) to a parent core. Non-limiting examples of suitable heteroaryls include 2-pyridinylmethyl, quinolinylmethyl and the like.
“Heterocyclyl” means a non-aromatic saturated monocyclic or multicyclic ring system comprising about 3 to about 10 ring atoms, preferably about 5 to about 10 ring atoms, in which one or more of the atoms in the ring system is an element other than carbon, for example nitrogen, oxygen or sulfur, alone or in combination. There are no adjacent oxygen and/or sulfur atoms present in the ring system. Preferred heterocyclyls contain about 5 to about 6 ring atoms. The prefix aza, oxa or thia before the heterocyclyl root name means that at least a nitrogen, oxygen or sulfur atom respectively is present as a ring atom. Any —NH in a heterocyclyl ring may exist protected such as, for example, as an —N(Boc), —N(CBz), —N(Tos) group and the like; such protections are also considered part of this invention. The heterocyclyl can be optionally substituted by one or more “ring system substituents” which may be the same or different, and are as defined herein. The nitrogen or sulfur atom of the heterocyclyl can be optionally oxidized to the corresponding N-oxide, S-oxide or S,S-dioxide. Non-limiting examples of suitable monocyclic heterocyclyl rings include piperidyl, pyrrolidinyl, piperazinyl, morpholinyl, thiomorpholinyl, thiazolidinyl, 1,4-dioxanyl, tetrahydrofuranyl, tetrahydrothiophenyl, lactam, lactone, and the like.
“Heterocyclylalkyl” means a heterocyclyl moiety as defined above linked via an alkyl moiety (defined above) to a parent core. Non-limiting examples of suitable heterocyclylalkyls include piperidinylmethyl, piperazinylmethyl and the like.
“Heterocyclenyl” means a non-aromatic monocyclic or multicyclic ring system comprising about 3 to about 10 ring atoms, preferably about 5 to about 10 ring atoms, in which one or more of the atoms in the ring system is an element other than carbon, for example nitrogen, oxygen or sulfur atom, alone or in combination, and which contains at least one carbon-carbon double bond or carbon-nitrogen double bond. There are no adjacent oxygen and/or sulfur atoms present in the ring system. Preferred heterocyclenyl rings contain about 5 to about 6 ring atoms. The prefix aza, oxa or thia before the heterocyclenyl root name means that at least a nitrogen, oxygen or sulfur atom respectively is present as a ring atom. The heterocyclenyl can be optionally substituted by one or more ring system substituents, wherein “ring system substituent” is as defined above. The nitrogen or sulfur atom of the heterocyclenyl can be optionally oxidized to the corresponding N-oxide, S-oxide or S,S-dioxide. Non-limiting examples of suitable heterocyclenyl groups include 1,2,3,4-tetrahydropyridine, 1,2-dihydropyridyl, 1,4-dihydropyridyl, 1,2,3,6-tetrahydropyridine, 1,4,5,6-tetrahydropyrimidine, 2-pyrrolinyl, 2-imidazolinyl, 2-pyrazolinyl, dihydroimidazole, dihydrooxazole, dihydrooxadiazole, dihydrothiazole, 3,4-dihydro-2H-pyran, dihydrofuranyl, fluorodihydrofuranyl, 7-oxabicyclo[2.2.1]heptenyl, dihydrothiophenyl, dihydrothiopyranyl, and the like.
“Heterocyclenylalkyl” means a heterocyclenyl moiety as defined above linked via an alkyl moiety (defined above) to a parent core.
It should be noted that in hetero-atom containing ring systems of this invention, there are no hydroxyl groups on carbon atoms adjacent to a N, O or S, as well as there are no N or S groups on carbon adjacent to another heteroatom. Thus, for example, in the ring: there is no —OH attached directly to carbons marked 2 and 5.
It should also be noted that tautomeric forms such as, for example, the moieties: are considered equivalent in certain embodiments of this invention.
“Alkynylalkyl” means an alkynyl-alkyl-group in which the alkynyl and alkyl are as previously described. Preferred alkynylalkyls contain a lower alkynyl and a lower alkyl group. The bond to the parent moiety is through the alkyl. Non-limiting examples of suitable alkynylalkyl groups include propargylmethyl.
“Heteroaralkyl” means a heteroaryl-alkyl-group in which the heteroaryl and alkyl are as previously described. Preferred heteroaralkyls contain a lower alkyl group. Non-limiting examples of suitable aralkyl groups include pyridylmethyl, and quinolin-3-ylmethyl. The bond to the parent moiety is through the alkyl.
“Hydroxyalkyl” means a HO-alkyl-group in which alkyl is as previously defined. Preferred hydroxyalkyls contain lower alkyl. Non-limiting examples of suitable hydroxyalkyl groups include hydroxymethyl and 2-hydroxyethyl.
“Acyl” means an H—C(O)—, alkyl-C(O)— or cycloalkyl-C(O)—, group in which the various groups are as previously described. The bond to the parent moiety is through the carbonyl. Preferred acyls contain a lower alkyl. Non-limiting examples of suitable acyl groups include formyl, acetyl and propanoyl.
“Aroyl” means an aryl-C(O)— group in which the aryl group is as previously described. The bond to the parent moiety is through the carbonyl. Non-limiting examples of suitable groups include benzoyl and 1-naphthoyl.
“Alkoxy” means an alkyl-O— group in which the alkyl group is as previously described. Non-limiting examples of suitable alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy and n-butoxy. The bond to the parent moiety is through the ether oxygen.
“Aryloxy” means an aryl-O— group in which the aryl group is as previously described. Non-limiting examples of suitable aryloxy groups include phenoxy and naphthoxy. The bond to the parent moiety is through the ether oxygen.
“Aralkyloxy” means an aralkyl-O— group in which the aralkyl group is as previously described. Non-limiting examples of suitable aralkyloxy groups include benzyloxy and 1- or 2-naphthalenemethoxy. The bond to the parent moiety is through the ether oxygen.
“Alkylthio” means an alkyl-S— group in which the alkyl group is as previously described. Non-limiting examples of suitable alkylthio groups include methylthio and ethylthio. The bond to the parent moiety is through the sulfur.
“Arylthio” means an aryl-S— group in which the aryl group is as previously described. Non-limiting examples of suitable arylthio groups include phenylthio and naphthylthio. The bond to the parent moiety is through the sulfur.
“Aralkylthio” means an aralkyl-S— group in which the aralkyl group is as previously described. Non-limiting example of a suitable aralkylthio group is benzylthio. The bond to the parent moiety is through the sulfur.
“Alkoxycarbonyl” means an alkyl-O— group. Non-limiting examples of suitable alkoxycarbonyl groups include methoxycarbonyl and ethoxycarbonyl. The bond to the parent moiety is through the carbonyl.
“Aryloxycarbonyl” means an aryl-O—C(O)— group. Non-limiting examples of suitable aryloxycarbonyl groups include phenoxycarbonyl and naphthoxycarbonyl. The bond to the parent moiety is through the carbonyl.
“Aralkoxycarbonyl” means an aralkyl-O—C(O)— group. Non-limiting example of a suitable aralkoxycarbonyl group is benzyloxycarbonyl. The bond to the parent moiety is through the carbonyl.
“Alkylsulfonyl” means an alkyl-S(O2)— group. Preferred groups are those in which the alkyl group is lower alkyl. The bond to the parent moiety is through the sulfonyl.
“Arylsulfonyl” means an aryl-S(O2)— group. The bond to the parent moiety is through the sulfonyl.
The term “substituted” means that one or more hydrogens on the designated atom is replaced with a selection from the indicated group, provided that the designated atom's normal valency under the existing circumstances is not exceeded, and that the substitution results in a stable compound. Combinations of substituents and/or variables are permissible only if such combinations result in stable compounds. By “stable compound” or “stable structure” is meant a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture, and formulation into an efficacious therapeutic agent.
The term “optionally substituted” means optional substitution with the specified groups, radicals or moieties.
When a functional group in a compound is termed “protected”, this means that the group is in modified form to preclude undesired side reactions at the protected site when the compound is subjected to a reaction. Suitable protecting groups will be recognized by those with ordinary skill in the art as well as by reference to standard textbooks such as, for example, T. W. Greene et al, Protective Groups in organic Synthesis (1991), Wiley, New York.
Prodrugs and solvates of the compounds of the invention are also contemplated herein. A discussion of prodrugs is provided in T. Higuchi and V. Stella, Pro-drugs as Novel Delivery Systems (1987) 14 of the A.C.S. Symposium Series, and in Bioreversible Carriers in Drug Design, (1987) Edward B. Roche, ed., American Pharmaceutical Association and Pergamon Press. The term “prodrug” means a compound (e.g, a drug precursor) that is transformed in vivo to yield a compound of Formulas (I)-(XXIII) or a pharmaceutically acceptable salt, hydrate or solvate of the compound. The transformation may occur by various mechanisms (e.g., by metabolic or chemical processes), such as, for example, through hydrolysis in blood. A discussion of the use of prodrugs is provided by U.S. Application Publication 2006/0040958 to Guzi et al. referencing T. Higuchi and W. Stella, “Pro-drugs as Novel Delivery Systems,” Vol. 14 of the A.C.S. Symposium Series, and in Bioreversible Carriers in Drug Design, ed. Edward B. Roche, American Pharmaceutical Association and Pergamon Press, 1987.
“Effective amount” or “therapeutically effective amount” is meant to describe an amount of compound or a composition of the present invention effective in inhibiting the above-noted diseases and thus producing the desired therapeutic, ameliorative, inhibitory or preventative effect.
The compounds of Formulas (I)-(XXIII) can form salts which are also within the scope of this invention. Reference to a compound of Formulas (I)-(XXIII) herein is understood to include reference to salts thereof, unless otherwise indicated. The term “salt(s)”, as employed herein, denotes acidic salts formed with inorganic and/or organic acids, as well as basic salts formed with inorganic and/or organic bases. In addition, when a compound of Formulas (I)-(XXIII) contains both a basic moiety, such as, but not limited to a pyridine or imidazole, and an acidic moiety, such as, but not limited to a carboxylic acid, zwitterions (“inner salts”) may be formed and are included within the term “salt(s)” as used herein. Pharmaceutically acceptable (i.e., non-toxic, physiologically acceptable) salts are preferred, although other salts are also useful. Salts of the compounds of Formulas (I)-(XXIII) may be formed, for example, by reacting a compound of Formulas (I)-(XXIII) with an amount of acid or base, such as an equivalent amount, in a medium such as one in which the salt precipitates or in an aqueous medium followed by lyophilization.
Exemplary acid addition salts include acetates, ascorbates, benzoates, benzenesulfonates, bisulfates, borates, butyrates, citrates, camphorates, camphorsulfonates, fumarates, hydrochlorides, hydrobromides, hydroiodides, lactates, maleates, methanesulfonates, naphthalenesulfonates, nitrates, oxalates, phosphates, propionates, salicylates, succinates, sulfates, tartarates, thiocyanates, toluenesulfonates (also known as tosylates,) and the like. Additionally, acids which are generally considered suitable for the formation of pharmaceutically useful salts from basic pharmaceutical compounds are discussed, for example, by P. Stahl et al, Camille G. (eds.) Handbook of Pharmaceutical Salts. Properties, Selection and Use. (2002) Zurich: Wiley-VCH; S. Berge et al, Journal of Pharmaceutical Sciences (1977) 66(1) 1-19; P. Gould, International J. of Pharmaceutics (1986) 33 201-217; Anderson et al, The Practice of Medicinal Chemistry (1996), Academic Press, New York; and in The Orange Book (Food & Drug Administration, Washington, D.C. on their website). These disclosures are incorporated herein by reference thereto.
Exemplary basic salts include ammonium salts, alkali metal salts such as sodium, lithium, and potassium salts, alkaline earth metal salts such as calcium and magnesium salts, salts with organic bases (for example, organic amines) such as dicyclohexylamines, t-butyl amines, and salts with amino acids such as arginine, lysine and the like. Basic nitrogen-containing groups may be quaternized with agents such as lower alkyl halides (e.g. methyl, ethyl, and butyl chlorides, bromides and iodides), dialkyl sulfates (e.g. dimethyl, diethyl, and dibutyl sulfates), long chain halides (e.g. decyl, lauryl, and stearyl chlorides, bromides and iodides), aralkyl halides (e.g. benzyl and phenethyl bromides), and others.
All such acid salts and base salts are intended to be pharmaceutically acceptable salts within the scope of the invention and all acid and base salts are considered equivalent to the free forms of the corresponding compounds for purposes of the invention.
Pharmaceutically acceptable esters of the present compounds include the following groups: (1) carboxylic acid esters obtained by esterification of the hydroxy groups, in which the non-carbonyl moiety of the carboxylic acid portion of the ester grouping is selected from straight or branched chain alkyl (for example, acetyl, n-propyl, t-butyl, or n-butyl), alkoxyalkyl (for example, methoxymethyl), aralkyl (for example, benzyl), aryloxyalkyl (for example, phenoxymethyl), aryl (for example, phenyl optionally substituted with, for example, halogen, C.sub.1-4alkyl, or C.sub.1-4alkoxy or amino); (2) sulfonate esters, such as alkyl- or aralkylsulfonyl (for example, methanesulfonyl); (3) amino acid esters (for example, L-valyl or L-isoleucyl); (4) phosphonate esters and (5) mono-, di- or triphosphate esters. The phosphate esters may be further esterified by, for example, a Cl20 alcohol or reactive derivative thereof, or by a 2,3-di (C6-24)acyl glycerol.
Compounds of F Formulas (I)-(XXIII) and salts, solvates, esters and prodrugs thereof, may exist in their tautomeric form (for example, as an amide or imino ether). All such tautomeric forms are contemplated herein as part of the present invention.
The compounds of Formulas (I)-(XXIII) may contain asymmetric or chiral centers, and, therefore, exist in different stereoisomeric forms. It is intended that all stereoisomeric forms of the compounds of Formulas (I)-(XXIII) as well as mixtures thereof, including racemic mixtures, form part of the present invention. In addition, the present invention embraces all geometric and positional isomers. For example, if a compound of Formulas (I)-(XXIII) incorporates a double bond or a fused ring, both the cis- and trans-forms, as well as mixtures, are embraced within the scope of the invention.
Diastereomeric mixtures can be separated into their individual diastereomers on the basis of their physical chemical differences by methods well known to those skilled in the art, such as, for example, by chromatography and/or fractional crystallization. Enantiomers can be separated by converting the enantiomeric mixture into a diastereomeric mixture by reaction with an appropriate optically active compound (e.g., chiral auxiliary such as achiral alcohol or Mosher's acid chloride), separating the diastereomers and converting (e.g., hydrolyzing) the individual diastereomers to the corresponding pure enantiomers. Also, some of the compounds of Formula (I), Formula (II), and Formula (III) may be atropisomers (e.g., substituted biaryls) and are considered as part of this invention. Enantiomers can also be separated, e.g., by use of chiral HPLC column.
It is also possible that the compounds of Formulas (I)-(XXIII) may exist in different tautomeric forms, and all such forms are embraced within the scope of the invention. Also, for example, all keto-enol and imine-enamine forms of the compounds are included in the invention.
All stereoisomers (for example, geometric isomers, optical isomers and the like) of the present compounds (including those of the salts, solvates, esters and prodrugs of the compounds as well as the salts, solvates and esters of the prodrugs), such as those which may exist due to asymmetric carbons on various substituents, including enantiomeric forms (which may exist even in the absence of asymmetric carbons), rotameric forms, atropisomers, and diastereomeric forms, are contemplated within the scope of this invention, as are positional isomers (such as, for example, 4-pyridyl and 3-pyridyl). (For example, if a compound of Formula (I), Formula (II), and Formula (III) incorporates a double bond or a fused ring, both the cis- and trans-forms, as well as mixtures, are embraced within the scope of the invention. Also, for example, all keto-enol and imine-enamine forms of the compounds are included in the invention.) Individual stereoisomers of the compounds of the invention may, for example, be substantially free of other isomers, or may be admixed, for example, as racemates or with all other, or other selected, stereoisomers. The chiral centers of the present invention can have the S or R configuration as defined by the IUPAC 1974 Recommendations.
The use of the terms “salt”, “solvate”, “ester”, “prodrug” and the like, is intended to equally apply to the salt, solvate, ester and prodrug of enantiomers, stereoisomers, rotamers, tautomers, positional isomers, racemates or prodrugs of the inventive compounds.
To ensure that the desired modified compounds have inhibiting abilities, these compounds will be tested as described herein. A variation in the inhibiting abilities is also contemplated.
Various modified compounds based on the compounds of Formulas (I)-(XXIII), will then be further tested to confirm the anti-WNV activity. Desired compounds would have anti-WNV activity with 50% inhibitory concentration (IC50) less than 5 μM and 50% cytotoxic concentration (CC 50) at greater than 50 μM in accordance with the live WNV virus assay as described below.
The compounds of the invention can be used as the starting point for further modification to make more potent compounds through structure activity relationship (SAR) studies. The structure of selected compounds can be modified through chemical synthesis. The compound derivatives will then be tested in WNV replicon cells. Changes than can increase the potency of the compound will be determined as important and can be further refined. Through such process more active compounds can be obtained. When a reasonably potent compound, for example, IC50 below 1 μM or low enough to be able to administer to animals is obtained, it can be evaluated in animal models for their activity against West Nile virus and other flavivirus infections including Dengue, yellow fever virus. These compounds can also be tested against other members of the flaviviridae family, e.g., Hepatitis C virus. Potentially, these compounds can be developed into small molecule antiviral therapeutics against many viruses in the flaviviridae family and possibly other viruses.
The compound can be further tested in a mouse model for WNV infection. There are available animal models that have been proven for this purpose (18).
While the invention has been described in detail and with reference to specific examples thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US06/25433 | 6/30/2006 | WO | 00 | 12/21/2007 |
| Number | Date | Country | |
|---|---|---|---|
| 60695770 | Jun 2005 | US |
