Discovery of 5-alkyl-2-pyrazol-oxazolidin-4-one derivatives as novel hepatitis B virus capsid assembly modulators.

The "magic methyl effect" strategy was used to design a series of 5-alkyl-2-pyrazol-oxazolidin-4-one derivatives as novel hepatitis B virus (HBV) capsid assembly modulators. Most of these compounds exhibited potent HBV inhibitory activities with low cytotoxicities in HepG2.2.15 cells. The most promising compounds 9d and 10b had single-digit nanomolar IC 50 values with a high selectivity index. Compared with the lead compound (3.0%), they caused 15% and 18% decreases in HBe antigen secretion at 1.0 μM, respectively. In addition, compounds 9d and 10b possessed good pharmacokinetic profiles with oral bioavailability values of 56.1% and 48.9%, respectively. These results indicated that the two compounds were potential therapeutic agents for HBV infection.