Inhibitory Effect of Root on the Cytochrome P450 3A Enzyme in vitro and in vivo.

PURPOSE

The aim of the present study was to investigate the interactions of the main components of root (ie, p-coumaric acid, acacetin, apigenin, buddleoside and Diosmetin-7-O-β-D-glucopyranoside) with cytochrome P450 3A enzyme activity both in vitro and in vivo.

METHODS

In vitro inhibition of drugs was assessed by incubating rat liver microsomes (RLMs) with a typical P450 3A enzyme substrate, midazolam, to determine their 50% inhibitory concentration (IC50) values. For the in vivo study, healthy male Sprague Dawley rats were consecutively administered acacetin or apigenin for 7 days at the dosage of 5 mg/kg after being randomly divided into 3 groups: Group A (control group), Group B (acacetin group) and Group C (apigenin group).

RESULTS

Among the five main components of root, only acacetin and apigenin showed inhibitory effects on the cytochrome P450 3A enzyme in vitro. The IC50 values of acacetin and apigenin were 58.46 μM and 8.20 μM, respectively. Additionally, the in vivo analysis results revealed that acacetin and apigenin could systemically inhibit midazolam metabolism in rats. The T, AUC and C of midazolam in group B and group C were significantly increased (<0.05), accompanied by a significant decrease in V and CL (<0.05).

CONCLUSION

Acacetin and apigenin could inhibit the activity of the cytochrome P450 3A enzyme in vitro and in vivo, indicating that herbal drug interactions might occur when taking root and midazolam synchronously.