Objective: To study the absorption and metabolism of five flavonoids of Herba Epimedii (icariin, epimedin A, epi-medin B, epimedin C and baohuoside I) in rat intestine.
Method: Using the rat intestinal perfusion model, the contents of the five flavonoids in perfusates were measured by HPLC and the permeability coefficients in different intestines were calculated.
Result: The permeabilities of five flavonoids in duodenum, jejunum, ileum, colon according to the sequence were as: icariin: 6.365, 5.349, 1.004, 0.601, epimedinA: 4.120, 3.397, 0.401, 0.257, epimedin B: 3.645, 3.135, 0.990 7, 0.434, epimedin C: 3.114, 2.882, 0.688, 0.470, baohuoside I: 2.324, 2.398, 1.529, 1.045, respectively. The analysis of the perfusates showed that icariin, epimedin A, epimedin B, epimedin C could be hydrolyzed in intestine. Icariin had two hydrolytic metabolites, whereas epimedin A, B, C only had one hydrolytic metabolite, respectively.
Conclusion: The results indicated that the absorption of all the five flavonoids was significantly different in different intestinal segments, and the permeability in ileum and colon was significantly lower than that of the duodenum and jejunum. The metabolites of icariin, epimedin A, epimedin B, epimedin C were related with their structures and enzymes in intestine, and the metabolites were more in duodenum, jejunum, whereas were less in ileum and colon.