Antiviral activity of various 1-(2'-deoxy-β-D-lyxofuranosyl), 1-(2'-fluoro-β-D-xylofuranosyl), 1-(3'-fluoro-β-D-arabinofuranosyl), and 2'-fluoro-2',3'-didehydro-2',3'-dideoxyribose pyrimidine nucleoside analogues against duck hepatitis B virus (DHBV) and human hepatitis B virus (HBV) replication.

Despite the existence of successful vaccine and antiviral therapies, infection with hepatitis B virus (HBV) continues to be a major global cause of acute and chronic liver disease and high mortality. We synthesized and evaluated several lyxofuranosyl, 2'-fluoroxylofuranosyl, 3'-fluoroarabinofuranosyl, and 2'-fluoro-2',3'-didehydro-2',3'-dideoxyribose pyrimidine nucleoside analogues for antiviral activities against hepatitis B virus. Among the compounds examined, 1-(2-deoxy-β-d-lyxofuranosyl)thymine (23), 1-(2-deoxy-β-d-lyxofuranosyl)-5-trifluoromethyluracil (25), 1-(2-deoxy-2-fluoro-β-d-xylofuranosyl)uracil (38), 1-(2-deoxy-2-fluoro-β-d-xylofuranosyl)thymine (39), 2',3'-dideoxy-2',3'-didehydro-2'-fluorothymidine (48), and 2',3'-dideoxy-2',3'-didehydro-2'-fluoro-5-ethyluridine (49) were found to possess significant anti-HBV activity against DHBV in primary duck hepatocytes with EC(50) values of 4.1, 3.3, 40.6, 3.8, 0.2, and 39.0 μM, respectively. Compounds 23, 25, 39, 48, and 49 (EC(50) = 41.3, 33.7, 19.2, 2.0-4.1, and 39.0 μM, respectively) exhibited significant activity against wild-type human HBV in 2.2.15 cells. Intriguingly, 25, 39, 48, and 49 retained sensitivity against lamivudine-resistant HBV containing a single mutation (M204I) and 48 emerged as an effective inhibitor of drug-resistant HBV with an EC(50) of 4.1 μM. In contrast, 50% inhibition could not be achieved by lamivudine at 44 μM concentration in the drug-resistant strain. The compounds investigated did not show cytotoxicity to host cells up to the highest concentrations tested.