Piperine is Anti-hyperlipidemic and Improves Endothelium-Dependent Vasorelaxation in Rats on a High Cholesterol Diet

Introduction. Piperine is a major ingredient of black pepper and long pepper, which are widely used as a spice and in Ayurvedic medicine. As an anti-hyperlipidemic, some reports show clear blood lipid reductions whilst others failed to show any effect. Therefore, we aimed to resolve this discrepancy and to show whether piperine could improve vascular endothelial function in cholesterol fed rats. Methods. Male Sprague-Dawley rats (180-250 g) were made hypercholesterolemic by daily intragastric gavage of emulsified cholesterol for 8 weeks and piperine was given 8 h after cholesterol as appropriate to prevent digestive/absorptive interactions. Animals were divided into 4 groups: (i) sham (control), (ii) cholesterol (HC), (iii) the cholesterol plus 40 mg/kg piperine (Pip40) and (iv) cholesterol plus 80 mg/kg piperine (Pip80). Serum total cholesterol (TC), triglycerides (TG) and high density lipoprotein (HDL) were measured at week 0 and week 8. At week 8, rats were killed and endothelium-dependent vasorelaxation induced by acetylcholine in isolated aortic rings. Results. Throughout the 8 week trial, treatment with piperine (40, 80 mg/kg) reduced body weight gain and food intake per day compared with control. The HC group exhibited elevation of both TC and TG. Piperine at 80 mg/kg but not low dose (40 mg/kg) partially reduced TC, while both doses effectively normalised the elevated TG. HDL was decreased in all animals including controls. Hypercholesterolemic and hypertriglyceridemic rats showed significant reduction of acetylcholine-induced vasorelaxation of isolated aortae and this was prevented by treatment with piperine. Conclusion. This study showed that piperine reduced body weight gain, lowered TC and fully normalised TG and endothelial-mediated vasorelaxation of aorta. Thus piperine could provide beneficial effects in weight control, anti-hyperlipidemia and counteracted the poor vascular endothelial function in hyperlipidemia. J Physiol Biomed Sci. 2012; 25(1): 27-30.