Design, Synthesis, and Antiviral Activity of 2‘-Deoxy-2‘-fluoro-2‘-C-methylcytidine, a Potent Inhibitor of Hepatitis C Virus Replication

Abstract

The pyrimidine nucleoside beta-d-2'-deoxy-2'-fluoro-2'-C-methylcytidine (1) was designed as a hepatitis C virus RNA-dependent RNA polymerase (HCV RdRp) inhibitor. The title compound was obtained by a DAST fluorination of N(4)-benzoyl-1-(2-methyl-3,5-di-O-benzoyl-beta-d-arabinofuranosyl]cytosine to provide N(4)-benzoyl-1-[2-fluoro-2-methyl-3,5-di-O-benzoyl-beta-d-ribofuranosyl]cytosine. The protected 2'-C-methylcytidine was obtained as a byproduct from the DAST fluorination and allowed for the preparation of two biologically active compounds from a common precursor. Compound 1 and 2'-C-methylcytidine were assayed in a subgenomic HCV replicon assay system and found to be potent and selective inhibitors of HCV replication. Compound 1 shows increased inhibitory activity in the HCV replicon assay compared to 2'-C-methylcytidine and low cellular toxicity.

2′-Deoxy-4′-azido Nucleoside Analogs Are Highly Potent Inhibitors of Hepatitis C Virus Replication Despite the Lack of 2′-α-Hydroxyl Groups

“…2Ј-␣-Fluorocytidine was also assessed as an inhibitor of HCV replication but was a potent inhibitor of cell proliferation in the HCV replicon system (7,37). The addition of a 2Ј-␤-methyl substituent resulted in the discovery of PSI-6130 (2Ј-␣-fluoro-2Ј-␤-methylcytidine), a potent inhibitor of HCV replication (38). Interestingly, PSI-6130 showed high selectivity against the closely related positive strand RNA virus bovine viral diarrhea virus, whereas the 2Ј-␣-hydroxy analog 2Ј-C-methylcytidine (NM107) inhibited both HCV and bovine viral diarrhea virus replication in cell culture (38).…”

“…The addition of a 2Ј-␤-methyl substituent resulted in the discovery of PSI-6130 (2Ј-␣-fluoro-2Ј-␤-methylcytidine), a potent inhibitor of HCV replication (38). Interestingly, PSI-6130 showed high selectivity against the closely related positive strand RNA virus bovine viral diarrhea virus, whereas the 2Ј-␣-hydroxy analog 2Ј-C-methylcytidine (NM107) inhibited both HCV and bovine viral diarrhea virus replication in cell culture (38). Fluoro-nucleosides may therefore provide considerable hydrogen bond acceptor functionality in the RNA polymerase active site (34), although such substitutions may also function by facilitating the formation of an RNA-like 3Ј-endo conformation in the RNA polymerase active site (39) or by accelerating the chemical reaction through electronic stabilization of the nucleophilic substitution reaction in the polymerase active site (40).…”

Characterization of the Metabolic Activation of Hepatitis C Virus Nucleoside Inhibitor β-d-2′-Deoxy-2′-fluoro-2′-C-methylcytidine (PSI-6130) and Identification of a Novel Active 5′-Triphosphate Species

“…(PSI-6130) was provided by Pharmasset, Inc. (18). A stock solution of 10 mM PSI-6130 was prepared in Dulbecco's phosphatebuffered saline and stored at Ϫ20°C.…”

Ralf Bartenschlager, Charles Rice, and Michael Sofia are honored with the 2016 Lasker~DeBakey Clinical Medical Research Award

“…It also had other characteristics that made it interesting to pursue, including the fact that the molecule was specific for HCV versus other viruses, it was able to inhibit the polymerases generated from multiple HCV genotypes, and had potential to have a high barrier to resistance." This molecule (PSI-6130) targets the HCV NS5B RNA polymerase (Figure 2) and thereby prevents elongation of the viral RNA genome (35). This molecule is part of a class of drugs known as direct acting antivirals, which target the virus as opposed to boosting the host immune response; thus, these drugs should have fewer adverse side effects.…”