In this study, we investigated the effects of treatment with Gingko biloba leaf extract (GLE) on intestinal transporter expression and gut microbiota composition in mice and the correlation between intestinal transporter expression and gut microbiota composition in mice. When GLE was orally administered to mice, intestinal BCRP expression was significantly suppressed. Pharmacokinetic studies showed that the maximum plasma concentration and area under the curve values of sulfasalazine were increased more than twice by treatment with GLE compared with those in the control group. GLE treatment significantly decreased the populations of Proteobacteria and Deferribacteres at the phylum level. Correlation analysis showed that BCRP expression was positively or negatively correlated with the composition of gut bacteria. In Caco-2 cells, GLE treatment did not affect BCRP expression, but treatment with the lysates of GLE-treated mouse feces significantly suppressed BCRP expression. These findings demonstrate that the suppression of intestinal BCRP expression following GLE treatment may occur through modulation of the gut microbiota composition. Thus, the present study suggests that modulation of gut microbiota composition may cause drug transporter-mediated herb–drug interactions.

Modulation of gut microbiota composition by Ginkgo biloba leaf extracts treatment may cause drug transporter-mediated herb–drug interactions.