In vitro evidence for bakuchiol's influence towards drug metabolism through inhibition of UDP-glucuronosyltransferase (UGT) 2B7

Background: Inhibition of drug-metabolizing enzymes (DMEs) has been regarded as one of the most important reason for clinical drug-drug interaction.

Aim: The aim of the present study is to evaluate the inhibition of bakuchiol towards UDP-glucuronosyltransferase (UGT) 2B isoforms.

Methods: In vitro recombinant UGT2B-catalyzed 4-methylumbelliferone glucuronidation was used as the probe reaction. Dixon plot and Lineweaver-Burk plot were employed to determine the inhibition kinetic type, and nonlinear regression of data was utilized to calculate the inhibition kinetic parameter (Ki). In vitro-in vivo extrapolation (IVIVE) was carried out to predict in vivo inhibition magnitude.

Results: Among the tested UGT2B isoforms, UGT2B7 was inhibited by the strongest intensity. The noncompetitive inhibition was demonstrated by the results obtained from Dixon plot and Lineweaver-Burk plot. The Ki value was calculated to be 10.7 µM. In combination with the reported concentration after an intravenous administration of bakuchiol (15 mg/kg) in rats, the high risk of in vivo inhibition of bakuchiol towards UGT2B7-catalyzed metabolism of drugs was indicated.

Conclusion: All these results provide an important information for the risk evaluation of the clinical utilization of bakuchiol.