Synthesis and Anti-HCV Activity of Sugar-Modified Guanosine Analogues: Discovery of As an HCV NS5B Polymerase Inhibitor for the Treatment of Chronic Hepatitis C

Chronic hepatitis C (CHC) is a major liver disease caused by the hepatitis C virus. The current standard of care for CHC can achieve cure rates above 95%; however, the drugs in current use are administered for a period of 8-16 weeks. A combination of safe and effective drugs with a shorter treatment period is highly desirable. We report synthesis and biological evaluation of a series of 2',3'- and 2',4'-substituted guanosine nucleotide analogues. Their triphosphates exhibited potent inhibition of the HCV NS5B polymerase with IC as low as 0.13 μM. In the HCV replicon assay, the phosphoramidate prodrugs of these analogues demonstrated excellent activity with EC values as low as 5 nM. A lead compound showed high levels of the nucleoside 5'-triphosphate in vitro in primary human hepatocytes and in vivo in dog liver following oral administration.