Synthesis and biological evaluation of Ribo 7-N/O/S pyrimidine 9-deaza C-nucleoside analogs as new antiviral agents for inhibiting HCV RNA-dependent RNA polymerases

Hepatitis C infection is caused by the bloodborne pathogen hepatitis C virus (HCV) and can lead to serious liver diseases and, ultimately, death if the treatment is ineffective. This work reports the synthesis and preclinical evaluation of 7 novel 9-O/N/S pyrimidine nucleosides, including compound 12, the triphosphate of known compound 7b. The nucleosides are 9-deaza modifications of adenosine and guanosine with beta-2 '-C-methyl substituent on the ribose. Within this series of compounds, a 9-deaza furopyrimidine analog of adenosine, compound 7b, showed high anti-HCV activity in vitro, good stability, low toxicity, and low genotoxicity when administrated in low doses, and an adequate pharmacokinetics profile. An improved synthesis of compound 7b compared to a previous study is also reported. Compound 12 was synthesized as a control to verify phosphorylation of 7b occurred in vivo.