Evaluation of acacetin inhibition potential against cytochrome P450 in vitro and in vivo.

Acacetin is a natural flavonoid that is widely distributed in plants and possesses numerous pharmacological activities. The aim of the present study was to investigate the effects of acacetin on the activities of the cytochrome P450 family members CYP1A2, CYP2B1, CYP2C11, CYP2D1, CYP2E1, and CYP3A2 in rat liver microsomes in vitro and rats in vivo to evaluate potential herb-drug interactions by using a cocktail approach. Phenacetin, bupropion, tolbutamide, dextromethorphan, chlorzoxazone, and midazolam were chosen as the probe substrates. An ultra-performance liquid chromatography-tandem mass spectrometry method was developed for the simultaneous detection of the probe substrates and their metabolites. In vitro, the mode of acacetin inhibition of CYP2B1, CYP2C11, and CYP2E1 was competitive, while mixed inhibition was observed for CYP1A2 and CYP3A2. The Ki values in this study were less than 8.32 μM. In vivo, the mixed probe substrates were administered by gavage after daily intraperitoneal injection with 50 mg/kg acacetin or saline for 2 weeks. The main pharmacokinetic parameters, area under the plasma concentration-time curve (AUC), plasma clearance (CL), and maximum plasma concentration (Cmax) of the probe substrates were significantly different in the experimental group than in the control group. Overall, the in vitro and in vivo results indicated that acacetin would be at high risk to cause toxicity and drug interactions via cytochrome P450 inhibition.