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

Bergenin, isolated from the herb of Bergenia purpurascens (Hook. f. et Thoms.) Engl., has anti-inflammatory, antitussive, and wound healing activities. However, whether bergenin affects the activity of human liver cytochrome P450 (CYP) enzymes remains unclear.In this study, the inhibitory effects of bergenin (100 μM) 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).

The results showed that bergenin inhibited the activity of CYP3A4, 2E1 and 2C9, with IC₅₀ values of 14.39, 22.83 and 15.11 μM, 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 K_i values of 7.71, 11.39 and 8.89 μM, respectively. In addition, bergenin is a time-dependent inhibitor for CYP3A4 with K_inact/K_I value of 0.025/3.50 μM^-1 min^-1.

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.