Antiatherosclerotic effects of dietary supplementations of garlic and turmeric: Restoration of endothelial function in rats

Protections of endothelial integrity by elimination of certain risk have proven to be effective in maintaining hernostasis and in slowing the progress of the cardiovascular disease. Indigenous drugs are the natural source of protection against these disorders, which can be used more effectively by the knowledge of their active ingredients as well as by their mechanism of action. Most prominent among these drugs are garlic, [Alium sativum L., Family: Liliaceae, Bulbs] and turmeric [Curcuma longa L., Family: Zingiberaceae, Rhizomes]; commonly used Indian traditional spices. In the present study, we examined the atheroscleroprotective potential of diet supplementation of garlic and turmeric by measuring serum lipid profile, changes in cardiovascular parameters i.e. arterial blood pressure, electrocardiogram and heart rate. We further tried to elucidate the mechanism of restoration of endothelial function and the role of endothelium-derived factors mainly, nitric oxide (NO) and cycloxygenase derived contracting factors. A notable restoration of arterial blood pressure was seen in animals on garlic and turmeric supplemented diet. Animals on supplemented diet showed a significantly enhanced vasorelaxant response to adenosine, acetylcholine, isoproterenol and contractile effect of 5-hyderoxytryptamine was significantly attenuated. Inhibition of these responses by L-NMMA was smaller in tissues from herbal treated animals. Incubation of tissues with L-arginine (10-5 M) resulted in a significant reversal of L-NMMA induced inhibition of endothelium-mediated relaxation, which appeared to be pronounced in rings from animals supplemented with herbs as compared to hypercholesterolemic animals. Addition of indomethacin (10(-5) M) augmented the relaxation in all the groups of animals. The present study demonstrated that garlic and turmeric are potent vasorelaxants as well as reduce the atherogenic properties of cholesterol. Whether combination of these vasodilators in cardiovascular disorders with increased peripheral vascular resistance remains to be determined. (c) 2005 Published by Elsevier Inc.