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The synthesis of new 2,6-disubstituted purine 2',3'-dideoxy-2',3'-difluoro-D-arabino nucleosides is reported. Their ability to block HIV and HCV replication along with their cytotoxicity toward Huh-7 cells, human lymphocyte, CEM and Vero cells was also assessed. Among them, β-2,6-diaminopurine nucleoside 25 and guanosine derivative 27 demonstrate potent anti-HIV-1 activity (EC50 = 0.56 and 0.65 µm; EC90 = 4.2 and 3.1 µm) while displaying only moderate cytotoxicity in primary human lymphocytes. [ABSTRACT FROM AUTHOR]

9-(2',3'-Dideoxy-2',3'-difluoro-β-D-arabinofuranosyl)adenine (20), 2-chloro-9-(2',3'-dideoxy-2,3-difluoro-β-D-arabinofuranosyl)adenine (22), as well as their respective α-anomers 21 and 23, were synthesized by the nucleobase anion glycosylation of intermediate 5-O-benzoyl-2,3-dideoxy-2,3-difluoro-α-D-arabinofuranosyl bromide (13) starting from methyl 5-O-benzyl-3-deoxy-3-fluoro-α-D-ribofuranoside (3) and methyl 5-O-benzoyl-α-D-xylofuranoside (10). These compounds were evaluated as potential inhibitors of HIV-1 and hepatitis C virus in human PBM and Huh-7 Replicon cells, respectively. The adenosine analog 20 demonstrated potent activity against HIV-1 in primary human lymphocytes with no apparent cytotoxicity. Conformation of pentofuranose ring of nucleoside 20 in solution was studied by PSEUROT calculations. [ABSTRACT FROM AUTHOR]

We recently discovered a novel compound, identified as N 3 ,5′-cyclo-4-(β-d-ribofuranosyl)- vic -triazolo[4,5- b ]pyridinin-5-one, with anti-hepatitis C virus (HCV) activity in vitro. The structure was confirmed by chemical synthesis from 2-hydroxy-5-nitropyridine. It showed anti-HCV activity with EC 50 =19.7 µM in replicon cells. Its 3′-deoxy sugar analogue was also synthesized, but was inactive against HCV in vitro. [ABSTRACT FROM AUTHOR]

The design and synthesis of new non-symmetrical NS5A inhibitors with sulfur containing amino acids is reported along with their ability to block HCV replication in an HCV 1b replicon system. These compounds display EC 50 values in the picomolar range with a large therapeutic index (>10 6 ). Moreover, cellular pharmacology studies show that our preferred compounds intracellularly deliver three potent NS5A inhibitors. [ABSTRACT FROM AUTHOR]

Abstract: Herein, we report the synthesis and structure–activity relationship studies of new analogs of boceprevir 1 and telaprevir 2. Introduction of azetidine and spiroazetidines as a P2 substituent that replaced the pyrrolidine moiety of 1 and 2 led to the discovery of a potent hepatitis C protease inhibitor 37c (EC50 =0.8μM). [Copyright &y& Elsevier]

Abstract: The synthesis of new ribo and 2′-β-C-methyl ribo Janus type nucleosides J-AA, J-AG and J-AU is reported along with their ability to block HCV and HIV replication. Their toxicity was also assessed in Huh7, human lymphocytes, CEM and Vero cells. [Copyright &y& Elsevier]

Abstract: Based on the symmetrical bidentate structure of the NS5A inhibitor BMS-790052, a series of new monodentate molecules were designed. The synthesis of 36 new non-dimeric NS5A inhibitors is reported along with their ability to block HCV replication in an HCV 1b replicon system. Among them compound 5a showed picomolar range activity along with an excellent selectivity index (SI > 90,000). [Copyright &y& Elsevier]

Abstract: Judicious modifications to the structure of the previously reported HCV NS5A inhibitor 1, resulted in more potent anti-HCV compounds with similar and in some cases improved toxicity profiles. The synthesis of 19 new NS5A inhibitors is reported along with their ability to block HCV replication in an HCV 1b replicon system. For the most potent compounds chemical stability, stability in liver microsomes and inhibition of relevant CYP450 enzymes is also presented. [Copyright &y& Elsevier]

Abstract: NS5A inhibitors are a new class of direct-acting antiviral agents which display very potent anti-HCV activity in vitro and in humans. Rationally designed modifications to the central biphenyl linkage of a known NS5A series led to selection of several compounds that were synthesized and evaluated in a HCV genotype 1b replicon. The straight triphenyl linked compound 11a showed similar anti-HCV activity to the clinical compound BMS-790052 and a superior cytotoxicity profile in three different cell lines, with an EC50 value of 26pM and a therapeutic index of over four million in an HCV replicon assay. This triphenyl analog warrants further preclinical evaluation as an anti-HCV agent. [Copyright &y& Elsevier]

Abstract: Thirty novel α- and β-d-2′-deoxy-2′-fluoro-2′-C-methyl-7-deazapurine nucleoside analogs were synthesized and evaluated for in vitro antiviral activity. Several α- and β-7-deazapurine nucleoside analogs exhibited modest anti-HCV activity and cytotoxicity. Four synthesized 7-deazapurine nucleoside phosphoramidate prodrugs (18–21) showed no anti-HCV activity, whereas the nucleoside triphosphates (22–24) demonstrated potent inhibitory effects against both wild-type and S282T mutant HCV polymerases. Cellular pharmacology studies in Huh-7 cells revealed that the 5′-triphosphates were not formed at significant levels from either the nucleoside or the phosphoramidate prodrugs, indicating that insufficient phosphorylation was responsible for the lack of anti-HCV activity. Evaluation of anti-HIV-1 activity revealed that an unusual α-form of 7-carbomethoxyvinyl substituted nucleoside (10) had good anti-HIV-1 activity (EC50 =0.71±0.25μM; EC90 =9.5±3.3μM) with no observed cytotoxicity up to 100μM in four different cell lines. [Copyright &y& Elsevier]

Abstract: Based on the anti-hepatitis C activity of 2′-C-methyl-adenosine and 2′-C-methyl-guanosine, a series of new modified purine 2′-C-methyl nucleosides was prepared as potential anti-hepatitis C virus agents. Herein, we report the synthesis of both 6-modified and 2-modified purine 2′-C-methyl-nucleosides along with their anti-HCV replication activity and cytotoxicity in different cells. [Copyright &y& Elsevier]

Abstract: Based on the promising drug resistance profile and potent anti-HIV activity of β-d-3′-azido-2′,3′-dideoxyguanosine, a series of purine modified nucleosides were synthesized by a chemical transglycosylation reaction and evaluated for their antiviral activity, cytotoxicity, and intracellular metabolism. Among the synthesized compounds, several show potent and selective anti-HIV activity in primary lymphocytes. [Copyright &y& Elsevier]