Effect of black pepper and piperine on bile secretion and composition in rats.

The influence of black pepper (Piper nigrum L.) and its active principle, piperine on the secretion and composition of bile was investigated in the rat. They were administered by gavage (black pepper at 250 or 500 mg and piperine at 12.5 or 25 mg/kg body wt.) or fed in the diet for 4 weeks (black pepper at 0.2 and 0.4%, piperine at 0.01 and 0.02%). The lower dose by gavage of black pepper caused an increase in bile solids while with other treatments bile secretion or dry matter in bile was not changed. Dietary feeding of black pepper caused an increase in bile flow with a concomitant decrease in bile solids -- a hydrocholagoguic effect. Cholesterol and bile acid output were not affected by black pepper or piperine at either level irrespective of the mode of administration; in contrast, the secretion of uronic acids in bile was enhanced by both levels of pepper as also of piperine indicating possible excretion of some of the components of black pepper or of piperine as glucuronides.