Fig. 2.

Inhibitory effects of selected flavonolignans on (S)-warfarin 7-hydroxylation activity in human liver microsomes. Human liver microsomes (0.1 mg/ml) were incubated with (S)-warfarin (4 μM) and flavonolignan (1, 10, or 100 μM; hatched, solid, and checkered bars, respectively) for 30 min. Reactions were initiated by the addition of NADPH (1 mM). (S)-Warfarin 7-hydroxylation activity in the presence of vehicle control (0.75% methanol, v/v) was 5.8 ± 0.1 pmol/min/mg microsomal protein. Bars and error bars denote means and S.D., respectively, of triplicate incubations. *, p < 0.05 versus flavonolignan at 10 μM; #, p < 0.05 versus flavonolignan at 1 μM (two-way ANOVA, followed by Tukey's test).