Influence of the gastrointestinal microflora and efflux transporters on the absorption of scutellarin and scutellarein

Scutellarin (SG) and its aglycone Scutellarein (S) are flavonoids of therapeutic cardiocerebrovascular disease. SG was hydrolyzed by bacterial enzyme into S which was absorbed in the intestine. The aim of this study was to determine the effects of the microflora in the intestinal lumen and the efflux transporter of intestinal epithelial cells on the absorption process of SG and S. After oral administration of antibiotics in Sprague-Dawley rats the reduced bacterial enzyme formation significantly hinders the absorption of SG whereas scarcely that of S. The absorption study in situ single-pass intestinal perfusion revealed that S could be absorbed throughout the intestine of rats. The effective intestinal permeability of S in the jejunum was much lower than in the other sections of the GI tract. The efflux transporter promoted SG secretion into lumen from enterocytes which hindered the absorption of both SG and S into the bloodstream. The efflux transporter protein inhibitor (verapamil probenecid and reserpine) remarkably enhanced the absorption of S and the bioconversion of S into SG in both the rat intestine and Caco-2-monolayer models.