Intestinal Absorption and Metabolism of Epimedium Flavonoids in Osteoporosis Rats

Herbal Epimdii is a traditional Chinese medicine used to treat osteoporosis. Its main pharmacological ingredients are flavonoids. In a previous study conducted in healthy animals, we showed that epimedium flavonoids could be hydrolyzed into secondary glycosides or aglycon by intestinal flora or enzymes, thereby enhancing their absorption and anti-osteoporosis activity. To study the medicine in the pathological state, epimedium flavonoids were incubated with intestinal mucosa and feces in vitro and intestinal perfusion in situ to explore the differences in absorption and metabolism between sham and osteoporosis rats. For osteoporosis rats, the hydrolysis rates of icariin, epimedin A, epimedin B, and epimedin C incubated with intestinal flora for 1 h reduced by 0.19, 0.26, 0.19, and 0.14, respectively, compared to that in sham rats. The hydrolysis rates of icariin, epimedin A, epimedin B, and epimedin C incubated with duodenal enzymes for 1 h reduced by 0.21, 0.24, 0.080, and 0.31, and with jejunum enzymes by 0.13, 0.090, 0.070, and 0.47, respectively, compared to the sham group. Additionally, the apparent permeability coefficient and elimination percentage of the four epimedium flavonoids in the duodenum, jejunum, ileum, and colon decreased by 29%~44%, 32%~50%, 40%~56%, and 27%~53% compared to that in sham rats, respectively. The main metabolites of the four epimedium flavonoids were the same for the two groups after intestinal perfusion, or flora and enzyme incubation. In conclusion, the amount and activity of intestinal flora and enzyme changed in ovariectomized rats, which affected the intestinal absorption and hydrolysis of epimedium flavonoids whose structures contain 7-glucose.