Effects of licorice extracts on the pharmacokinetics of brucine in rats and its possible mechanism.

The detoxification effects of licorice are believed to be related to its pharmacokinetic (PK) interference. This paper aimed to evaluate the effects of licorice water extracts (LWE) on the pharmacokinetics of brucine. Rats were administered brucine and/or LWE. The pharmacokinetic behavior of brucine and bioactive components of licorice were quantified by HPLC-MS/MS. P-glycoprotein (P-gp) inhibitor verapamil, real time PCR, vesicular transport assay and everted gut sacs were employed to investigate its possible mechanism. We found LWE reduced the Cmax and AUC of oral brucine in a dose-dependent way. In contrast, the AUC values of intraperitoneal brucine showed no significant difference between LWE treated and untreated rats, which indicating the intestinal absorption of brucine was influenced by LWE. We found that high dose of LWE activated the transport activity of P-gp in vesicular transport assay, while the mRNA level of P-gp in the intestinal was not affected by licorice. Moreover, high dose of LWE decreased the intestinal absorption of brucine in the everted gut sacs model, which could over turned by verapamil. These results suggested that a single high dose of LWE could impair the intestine absorption of brucine, and its potential mechanism may be mediated by P-gp in intestine.