Constituents of Indonesian medicinal plant averrhoa bilimbi and Their Cytochrome P450 3A4 and 2D6 Inhibitory Activities

Abstract

As constituents of Averrhoa bilimbi leaves we identified three new compounds (1-3) together with 12 known ones (4-15); their inhibitory activities on cytochrome P450 3A4 (CYP3A4) and 2D6 (CYP2D6) were examined. Among the isolated compounds, the mixture of 1 and 2, and compounds 4 and 9 showed strong inhibition on CYP3A4, but mild or no inhibition on CYP2D6. These compounds revealed the characteristics of 1) time-and concentrationdependent inhibition, 2) requirement of NADPH for the inhibition, 3) no protection by nucleophiles, and 4) suppression of the inhibition by competitive inhibitor. Thus, they are suggested to be mechanism-based inactivators of CYP3A4 and CYP2D6. The kinetic parameters for the inactivation (kinact and KI) were 0.19 min-1 and 36.7 μM for the mixture of 1 and 2, 0.126 min-1 and 10.5 μM for 4, and 0.29 min-1 and 23.4 μM for 9.