Reduction of oxidative stress and atherosclerosis in hyperlipidemic rabbits by Dioscorea rhizome

Hyperlipidemia may induce oxidative stress, which is important in the pathogenesis of atherosclerosis. Dioscorea rhizome (DR) is the powdered form of yams, and possesses antioxidant and hypolipidemic function. We therefore investigated the antioxidative and antiatherogenic effects of DR on hyperlipidemic rabbits. The control group was fed chow containing 0.5% cholesterol and 10% corn oil. The probucol and DR groups were fed the same diet as the control group but with the addition of 100 mg probucol/kg chow and 200 mg DR/kg chow, respectively. Total cholesterol and triacylglycerol plasma levels, RBC hemolysis T50, lucigenin chemiluminescence, and luminol chemiluminescence increased in the control group compared with the normal group, and decreased in the probucol and DR groups compared with the control group. The activity of antioxidant enzymes superoxide dismutase and catalase was significantly higher in the probucol and DR group than in the control group. The level of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in liver DNA was lower in the probucol and DR group than in the control group. Eighty percent of the intimal surface of the thoracic aorta was covered with atherosclerotic lesions in the control group but only 40% of the surface was covered in the DR group. These results suggest that supplementation with DR reduces oxidative stress and attenuates atherosclerosis in hyperlipidemic rabbits.