Metabolism of 6''-O-Xylosyltectoridin and Tectoridin by Human Intestinal Bacteria and Their Hypoglycemic and in Vitro Cytotoxic Activities.

6"-O-Xylosyltectoridin and tectoridin isolated from the flowers of Pueraria thunbergiana (Leguminosae), are metabolized to tectorigenin by human intestinal bacteria. Although tectoridin is metabolized to tectorigenin by most intestinal bacteria, 6"-O-xylosyltectoridin is metabolized to tectorigenin via tectoridin by only a few intestinal bacteria, such as Bifidobacterium breve K-110 and Eubacterium A-44. The metabolite, tectorigenin, had more potent hypoglycemic activity as well as in vitro cytotoxic activity against tumor cell lines than 6"-O-xylosyltectoridin and tectoridin. These results suggest that 6"-O-xylosyltectoridin and tectoridin are prodrugs which can be transformed to the active agents by human intestinal bacteria.