Bioavailability of finger millet (Eleusine coracana) phenolic compounds in rat as influenced by coadministered piperine.

Effect of co-administered piperine on the bioavailability of finger millet (FM) phenolic compounds was investigated in rats. FM phenolic extract was orally administered (100 mg kg−1) to rats along with or without piperine (20 mg kg−1). Blood, liver, intestine, kidney, and brain were analyzed for the absorbed phenolics at varying time intervals and their urinary excretion was monitored. Phenolic concentration in plasma was maximal at 8 h after oral administration of FM polyphenols (13 µg mL−1), salicylic acid being the predominant compound. Area under the curve (AUC) for phenolic concentration in plasma significantly increased (166 μg h mL−1 from 113) with piperine co-administration. Phenolic acids ̶ gentisic, sinapic, and ferulic acids were prominent in plasma when administered along with piperine. Phenolic concentration in liver, kidney, small intestine, and brain increased with piperine co-administration. Maximum appearance of phenolics in plasma, small intestine and kidney following the oral administration was advanced with piperine co-administration. FM-derived phenolics were found in brain at all time intervals, their concentration being higher when co-administered with piperine. Urinary phenolics excretion was higher when co-administered with piperine presumably because of higher absorption. Thus, piperine co-administration significantly increased absorption of orally administered FM phenolics and their retention in the body.