Comparative Metabolism of the Eight Main Bioactive Ingredients of Gegen Qinlian Decoction by the Intestinal Flora of Diarrhoeal and Healthy Piglets.

Diarrhoeal diseases alter the composition of intestinal flora, thereby affecting the efficacy of herbal medicinal formulations. Gegen Qinlian decoction (GQD), a Chinese traditional herbal formulation, is widely used to treat infectious diarrhoea. However, little is known about the microbial disposition of GQD in the diarrhoeal state. In this study, the comparative metabolism of components of GQD by diarrhoeal and normal intestinal flora was investigated in vitro. UPLC-MS/MS was performed for simultaneous analysis of eight ingredients of GQD in bacterial solution. The type, activities, and sources of microbial enzymes were also investigated. Microbial metabolism of daidzin, genistin and liquiritin (metabolized by beta-glucosidase); baicalin, wogonoside and glycyrrhizin (metabolized by beta-glucuronidase); and berberine and coptisine (metabolized via nitroreductase) was faster in the diarrhoeal group than in the normal group. Moreover, the activities of these enzymes in the diarrhoeal group were higher than those in the normal group. This difference might be associated with the increase in Escherichia spp. Thus, a change in the metabolism of components by diarrhoeal intestinal flora is associated with a preponderance of Escherichia spp., which might improve the efficacy of GQD. These findings have implications for understanding the action mechanism of GQD for diarrhoea treatment in terms of the microbial milieu.