Effects of friedelin on the intestinal permeability and bioavailability of apigenin.

Abstract

Although apigenin possesses diverse pharmacological activities, its utilization as a bioactive substance is limited by poor oral bioavailability. The aim of this study was to improve the bioavailability of apigenin by co-administration of friedelin. To achieve this, the intestinal permeability of apigenin in the absence or presence of friedelin was investigated in both Caco-2 cells and single-pass rat intestinal perfusion models. The apparent permeability coefficients (Papp) of apigenin in the presence of friedelin were substantially increased by 1.63- and 1.60-fold in Caco-2 cells and single-pass rat intestinal perfusion models, respectively. Such increases in the Papp indicated that friedelin could significantly enhance the absorption of apigenin into the body. The increased bioavailability of apigenin in rats following the oral administration of apigenin 50mg/kg body weight with friedelin 50mg/kg body weight was further confirmed by increases in the peak concentration of apigenin (Cmax), elimination half-life (T1/2) and area under the plasma concentration-time curve (AUC). Friedelin suppressed ATPase activity of P-glycoprotein (P-gp) indicated that the improved bioavailability of apigenin may be ascribed to P-gp inhibition by the co-administered friedelin.