[Show abstract][Hide abstract] ABSTRACT: The synthesis of a novel series of 1-carba-isoflavanones through the α-arylation of α-tetralones is described. Several of these compounds demonstrated potent activity and selectivity in-vitro against HCV replicon reporter cells. Compound 10 (LQB-314) exhibited the best profile being active and selective in both replicon reporter cells (IC50 1.8 μM, SI > 111 and IC50 4.3 μM, SI > 46 in Huh7/Rep-Feo1b and Huh7.5-FGR-JC1-Rluc2A, respectively). Compound 3 (LQB-307) was the more potent and selective for Huh7.5-FGR-JC1-Rluc2A replicon reporter cells (IC50 1.5 μM, SI > 101.4).
European Journal of Medicinal Chemistry 03/2015; 93. DOI:10.1016/j.ejmech.2015.01.057 · 3.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract Arachidonic acid is an unsaturated fatty acid liberated from phospholipids of cell membranes. NSAIDs are known as targets of cyclooxygenase enzyme (COX-1, COX-2 and COX-3) in arachidonic acid metabolism. This mechanism of COX-2 in carcinogenesis causes cancer. In addition, COX-2 plays a role in the early stages of hepatocarcinogenesis. Hepatitis C virus (HCV) infection is cause of liver cirrhosis and hepatocellular carcinoma (HCC). The aim of our study was to improve effective agents against HCV. A novel series of new etodolac 1,2,4-triazoles derivatives (4a-h) have been synthesized and investigated for their activity against HCV NS5B polymerase. Compound 4a was found to be the most active with IC50 value of 14.8 µM. In accordance with these results, compound 4a was screened for anti-cancer activity on liver cancer cell lines (Huh7, Mahlavu, HepG2, FOCUS). Compound 4a showed anti-cancer activity against Huh7 human hepatoma cell line with IC50 value of 4.29 µM. Therefore, compound 4a could be considered as a new anti-cancer and anti-HCV lead compound.
Journal of Enzyme Inhibition and Medicinal Chemistry 02/2015; 30(5):1-8. DOI:10.3109/14756366.2014.971780 · 2.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have previously identified the pyrazolobenzothiazine scaffold as a promising chemotype against hepatitis C virus (HCV) NS5B polymerase, a validated and promising anti-HCV target. Herein we describe the design, synthesis, enzymatic and cellular characterization of new pyrazolobenzothiazines as anti-HCV inhibitors. The binding site for a representative derivative was mapped to NS5B palm site I employing a mutant counter screen assay, thus validating our previous in silico predictions. Derivative 2b proved to be the best selective anti-HCV derivative within the new series, exhibiting IC50 value of 7.9 µM against NS5B polymerase and antiviral effect (EC50 = 8.1 µM, EC90 = 23.3 µM) coupled with the absence of any antimetabolic effect (CC50 >224 µM, SI >28) in a cell based HCV replicon system assay. Significantly, microscopic analysis showed that, unlike the parent compounds, derivative 2b did not show any significant cell morphological alterations. Furthermore, since most of the pyrazolobenzothiazines tested altered cell morphology, this undesired aspect was further investigated by exploring possible perturbation of lipid metabolism during compound treatment.
[Show abstract][Hide abstract] ABSTRACT: 1-Aroyl-3,5-dimethyl-1H-pyrazole derivatives (7-12) were synthesized from some hydrazides (1-6) with acetylacetone (2,4-pentanedione) by microwave irradiation. Their structures were elucidated by FT-IR and 1H-NMR spectral data and elemental analysis. Compound activities were evaluated against HCV NS5B and in cell based HCV reporters. Compound 8 was the most promising of this series in inhibiting intracellular NS5B activity and HCV RNA replication in reporter cells. The selected compounds 9, 10 and 12 by National Institue of Health were screened for their anticancer activity against 60 human tumor cell lines. Compound 9 (3-[(3,5-dimethyl-1H-pyrazol-1-yl)carbonyl]-2′,4′- difluorobiphenyl-4-ol) possessed significant activity against human immortalized myelogenous leukemia (K-562) exhibiting cell growth promotion 30.05%, with inhibition of 69.95% at 10-5M concentration. Compounds 3 and 9 were evaluated for cell viability and growth inhibition by K-562 cells of MTT assay, at different doses (10-6- 10-2M). Further, compound 9 exhibited anticancer activity against K-562 cells with IC50 value of 4 μM . Apoptosis levels of compound 9 were determined for three different concentrations (10-6, 10-5 and 10-3M) at two time points (24 and 48 h). Compound 9 induced apoptosis of K-562 cells, thus suggesting that compound 9 might be a potential chemopreventive agent for chronic myelogenous leukemia.
Letters in Drug Design & Discovery 02/2014; 11(2):121-131. DOI:10.2174/15701808113109990069 · 0.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The hepatitis C virus (HCV) NS5B RNA dependent RNA polymerase (RdRP) is a crucial and unique component of the HCV RNA replication machinery and a validated target for drug discovery. Multiple crystal structures of NS5B inhibitor complexes have facilitated the identification of novel compound scaffolds through in silico analysis. With the goal of discovering new NS5B inhibitor leads, HCV NS5B crystal structures bound with inhibitors in the palm and thumb allosteric pockets in combination with ligands with known inhibitory potential were explored for a comparative pharmacophore analyses. The energy-based and 3D QSAR based pharmacophore models were validated using enrichment analysis and the six models thus developed were employed for high-throughput virtual screening and docking to identify non-peptidic leads. The hits derived at each stage were analyzed for diversity based on the six pharmacophore models, followed by molecular docking and filtering based on their interaction with NS5B amino acids in the binding pocket and 3D QSAR predictions. The resulting 10 hits displaying diverse scaffold were then screened employing biochemical and cell based NS5B and anti-HCV inhibition assays. Of these, two molecules H-5 and H-6 were the most promising exhibiting IC50 values of 28.8 µM and 47.3 µM against NS5B polymerase and anti-HCV inhibition of 96% and 86% at 50 µM, respectively. The identified leads comprising of benzimidazole (H-5) and pyridine (H-6) scaffolds thus constitute prototypical molecules for further optimization and development as NS5B inhibitors.
Journal of Chemical Information and Modeling 01/2014; 54(2). DOI:10.1021/ci400644r · 3.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A novel series of new flurbiprofen hydrazide derivatives 2-(2-fluorobiphenyl-4-yl)-N′-[(substituted phenyl/5-nitro-2-furyl)methylene]propanehydrazide (3a–k), 2-(2-fluorobiphenyl-4-yl)-N-(2-substituted-4-oxo-1,3-thiazolidine-3-yl)propanamide (4a–b, 4d–k), 2-[2-(2-fluorobiphenyl-4-yl) propanoyl]-N-substituted hydrazinecarbothioamide (5a–h) and 2-(2-fluorobiphenyl-4-yl)-N′-[(3-methyl-4-oxo-1,3-thiazolidin-2-ylidene]propanehydrazide (6a–b, 6e and 6g) has been synthesized in this study. All synthesized compounds were screened for antimicrobial activity against various bacterial and fungal strains. Additionally, compounds were evaluated for the ability to inhibit Hepatitis C virus NS5B polymerase. The most active 4-thiazolidinone compound was 4k (SGK119) with 67.0 % and thiosemicarbazide compound was 5d (SGK123) with 69.50 % inhibition at 200 μM against hepatitis C virus NS5B RNA polymerase. Anticancer activity of the selected compounds (3i, 3j, 3h, 4d, 4i and 6b) was determined at a single dose towards the full panel of 60 human cancer cell lines by the National Cancer Institute (NCI). 2-(2-Fluoro-4-biphenylyl)-N-[2-[4-(trifluoromethyl)phenyl]-4-oxo-1,3-thiazolidine-3-yl]propanamide 4d, containing thiazolidinone ring, demonstrated the most marked effect with 20.80 % growth percent on leukaemia cancer cell line SR at 10−5 M. The results demonstrated that none of the compounds tested have anticandidal and antifungal activities, but two of them (4a and 4i) showed antibacterial inhibition against Micrococcus luteus, and Staphylococcus cohnii and Staphylococcus aureus, respectively.
Medicinal Chemistry Research 12/2013; 22(12). DOI:10.1007/s00044-013-0550-3 · 1.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have previously reported that the 6-aminoquinolone chemotype is a privileged scaffold to obtain antibacterial and antiviral agents. Herein we describe the design, synthesis, enzymatic and cellular characterization of new 6-aminoquinolone derivatives as potent inhibitors of NS5B polymerase, an attractive and viable therapeutic target to develop safe anti-HCV agents. The 6-amino-7-[4-(2-pyridinyl)-1-piperazinyl] quinolone derivative 8 proved to be the best compound of this series, exhibiting IC50 value of 0.069 μM against NS5B polymerase and selective antiviral effect (EC50 = 3.03 µM, EC90 =13.5 μM) coupled with the absence of any cytostatic effect (CC50 >163 µM, SI >54) in a HCV subgenomic replicon system. These results clearly indicate that the 6-aminoquinolone scaffold is worthy of further investigation in the context of NS5B-targeted HCV drug discovery programs.
[Show abstract][Hide abstract] ABSTRACT: Hepatitis C virus (HCV) NS5B polymerase is an important and attractive target for the development of anti-HCV drugs. Here we report on the design, synthesis and evaluation of twenty-four novel allosteric inhibitors bearing the 4-thiazolidinone scaffold as inhibitors of HCV NS5B polymerase. Eleven compounds tested were found to inhibit HCV NS5B with IC50 values ranging between 19.8 and 64.9 μM. Compound 24 was the most active of this series with an IC50 of 5.6 μM. A number of these derivatives further exhibited strong inhibition against HCV 1b and 2a genotypes in cell based antiviral assays. Molecular docking analysis predicted that the thiazolidinone derivatives bind to the NS5B thumb pocket-II (TP-II). Our results suggest that further optimization of the thiazolidinone scaffold may be possible to yield new derivatives with improved enzyme- and cell-based activity.
European Journal of Medicinal Chemistry 09/2013; 69C:931-941. DOI:10.1016/j.ejmech.2013.08.043 · 3.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hepatitis C virus (HCV) NS5B polymerase is a key target for anti-HCV therapeutics development. Herein, we report the synthesis and in vitro evaluation of anti-NS5B polymerase activity of a molecular hybrid of our previously reported lead compounds 1 (IC50=7.7μM) and 2 (IC50=10.6μM) as represented by hybrid compound 27 (IC50=6.7μM). We have explored the optimal substituents on the terminal phenyl ring of the 3-phenoxybenzylidene moiety in 27, by generating a set of six analogs. This resulted in the identification of compound 34 with an IC50 of 2.6μM. To probe the role of stereochemistry towards the observed biological activity, we synthesized and evaluated the d-isomers 41 (IC50=19.3μM) and 45 (IC50=5.4μM) as enantiomers of the l-isomers 27 and 34, respectively. The binding site of compounds 32 and 34 was mapped to palm pocket-I (PP-I) of NS5B. The docking models of 34 and 45 within the PP-I of NS5B were investigated to envisage the molecular mechanism of inhibition.
[Show abstract][Hide abstract] ABSTRACT: The NS5B RNA-dependent RNA polymerase is an attractive target for the development of novel and selective inhibitors of hepatitis C virus replication. To identify novel structural hits as anti-HCV agents, we performed structure-based virtual screening of our in-house library followed by rational drug design, organic synthesis, and biological testing. These studies led to the identification of pyrazolobenzothiazine scaffold as a suitable template for obtaining novel anti-HCV agents targeting the NS5B polymerase. The best compound of this series was the meta-fluoro-N-1-phenyl pyrazolobenzothiazine derivative 4a, which exhibited an EC50 = 3.6 μM, EC90 = 25.6 μM, and CC50 > 180 μM in the Huh 9-13 replicon system, thus providing a good starting point for further hit evolution.
[Show abstract][Hide abstract] ABSTRACT: A series of novel N-(3-substituted aryl/alkyl-4-oxo-1,3-thiazolidin-2-ylidene)-4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamides 2a-e were synthesized by the addition of ethyl a-bromoacetate and anhydrous sodium acetate in dry ethanol to N-(substituted aryl/alkylcarbamothioyl)-4-[5-(4-methylphenyl)-3-(trifluoro-methyl)-1H-pyrazol-1-yl]benzene sulfonamides 1a-e, which were synthesized by the reaction of alkyl/aryl isothiocyanates with celecoxib. The structures of the isolated products were determined by spectral methods and their anti-inflammatory, analgesic, antioxidant, anticancer and anti-HCV NS5B RNA-dependent RNA polymerase (RdRp) activities evaluated. The compounds were also tested for gastric toxicity and selected compound 1a was screened for its anticancer activity against 60 human tumor cell lines. These investigations revealed that compound 1a exhibited anti-inflammatory and analgesic activities and further did not cause tissue damage in liver, kidney, colon and brain compared to untreated controls or celecoxib. Compounds 1c and 1d displayed modest inhibition of HCV NS5B RdRp activity. In conclusion, N-(ethylcarbamothioyl)-4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide (1a) may have the potential to be developed into a therapeutic agent.
[Show abstract][Hide abstract] ABSTRACT: Hepatitis C virus (HCV) NS5B polymerase is a key target for the development of anti-HCV drugs. Here we report on the identification of novel allosteric inhibitors of HCV NS5B through a combination of structure-based virtual screening and in vitro NS5B inhibition assays. One hundred and sixty thousand compounds from the Otava database were virtually screened against the thiazolone inhibitor binding site on NS5B (thumb pocket-2, TP-2), resulting in a sequential down-sizing of the library by 2.7 orders of magnitude to yield 59 NS5B non-nucleoside inhibitor (NNI) candidates. In vitro evaluation of the NS5B inhibitory activity of the 59 selected compounds resulted in a 14% hit rate, yielding 8 novel structural scaffolds. Of these, compound 1 bearing a 4-hydrazinoquinazoline scaffold was the most active (IC(50) = 16.0 μM). The binding site of all 8 NNIs was mapped to TP-2 of NS5B as inferred by a decrease in their inhibition potency against the M423T NS5B mutant, employed as a screen for TP-2 site binders. At 100 μM concentration, none of the eight compounds exhibited any cytotoxicity, and all except compound 8 exhibited between 40 and 60% inhibition of intracellular NS5B polymerase activity in BHK-NS5B-FRLuc reporter cells. These inhibitor scaffolds will form the basis for future optimization and development of more potent NS5B inhibitors.
European Journal of Medicinal Chemistry 09/2012; 58C:258-264. DOI:10.1016/j.ejmech.2012.09.010 · 3.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hepatitis C virus (HCV) NS5B polymerase is pivotal for replicating the viral RNA genome and is therefore an important target for therapeutic intervention of HCV infection. Starting from our lead compound (2-(5-(2,4-dichlorobenzylidene)-4-oxo-2-thioxothiazolidin-3-yl)-3-phenylpropanoic acid, IC50 = 10.6 µM), we have carried out extensive SAR around the C-5-benzylidene substituent leading to the identification of (2-(5-(3-phenoxybenzylidene)-4-oxo-2-thioxothiazolidin-3-yl)-3-phenylpropanoic acid) with an IC50 value of 7.7 µM. Further SAR optimization will be based on identification of optimal substituents at the phenoxy ring. The synthesis, biological evaluation and SAR of these derivatives will be discussed.
244th American Chemical Society National Meeting and Exposition, Philadelphia, PA; 08/2012
[Show abstract][Hide abstract] ABSTRACT: Structure-based studies led to the identification of a constrained derivative of S-trityl-l-cysteine (STLC) scaffold as a candidate inhibitor of hepatitis C virus (HCV) NS5B polymerase. A panel of STLC derivatives were synthesized and investigated for their activity against HCV NS5B. Three STLC derivatives, 9, F-3070, and F-3065, were identified as modest HCV NS5B inhibitors with IC(50) values between 22.3 and 39.7 μM. F-3070 and F-3065 displayed potent inhibition of intracellular NS5B activity in the BHK-NS5B-FRLuc reporter and also inhibited HCV RNA replication in the Huh7/Rep-Feo1b reporter system. Binding mode investigations suggested that the STLC scaffold can be used to develop new NS5B inhibitors by further chemical modification at one of the trityl phenyl group.
European Journal of Medicinal Chemistry 03/2012; 49:191-9. DOI:10.1016/j.ejmech.2012.01.010 · 3.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hepatitis C virus (HCV) NS5B polymerase is a key target for anti-HCV therapeutics development. Here we report the synthesis and biological evaluation of a new series of α,γ-diketo acids (DKAs) as NS5B polymerase inhibitors. We initiated structure-activity relationship (SAR) optimization around the furan moiety of compound 1a [IC(50) = 21.8 μM] to achieve more active NS5B inhibitors. This yielded compound 3a [IC(50) = 8.2 μM] bearing the 5-bromobenzofuran-2-yl moiety, the first promising lead compound of the series. Varying the furan moiety with thiophene, thiazole and indazole moieties resulted in compound 11a [IC(50) = 7.5 μM] bearing 3-methylthiophen-2-yl moiety. Finally replacement of the thiophene ring with a bioisosteric phenyl ring further improved the inhibitory activity as seen in compounds 21a [IC(50) = 5.2 μM] and 24a [IC(50) = 2.4 μM]. Binding mode of compound 24a using glide docking within the active site of NS5B polymerase will form the basis for future SAR optimization.
European Journal of Medicinal Chemistry 08/2011; 46(10):5138-45. DOI:10.1016/j.ejmech.2011.08.028 · 3.45 Impact Factor