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.