In vitro inhibitory effects of bergenin on human liver cytochrome P450 enzymes

Context: Bergenin, isolated from the herb of Bergenia purpurascens (Hook. f. et Thoms.) Engl., has antiinflammatory, antitussive, and wound healing activities. However, whether bergenin affects the activity of human liver cytochrome P450 (CYP) enzymes remains unclear. Materials and methods: In this study, the inhibitory effects of bergenin (100 mu M) on the eight human liver CYP isoforms (i. e., 1A2, 3A4, 2A6, 2E1, 2D6, 2C9, 2C19 and 2C8) were investigated, enzyme kinetics and time-dependent inhibition studies were also performed in vitro using human liver microsomes (HLMs). Results: The results showed that bergenin inhibited the activity of CYP3A4, 2E1 and 2C9, with IC50 values of 14.39, 22.83 and 15.11 lM, respectively, but other CYP isoforms were not affected. Enzyme kinetic studies showed that bergenin was not only a non-competitive inhibitor of CYP3A4, but also a competitive inhibitor of CYP2E1 and 2C9, with Ki values of 7.71, 11.39 and 8.89 lM, respectively. In addition, bergenin is a time-dependent inhibitor for CYP3A4 with K-inact/K-I value of 0.025/3.50 mu M-1 min(-1). Discussion and conclusions: The in vitro studies of bergenin with CYP isoforms indicate that bergenin has the potential to cause pharmacokinetic drug interactions with other co-administered drugs metabolized by CYP3A4, 2E1 and 2C9. Further clinical studies are needed to evaluate the significance of this interaction.