Increase of Vitamin E Content in LDL and Reduction of Atherosclerosis in Cholesterol-Fed Rabbits by a Water-Soluble Antioxidant-Rich Fraction of Salvia miltiorrhiza

Abstract

Abstract —Antioxidants that prevent LDL from oxidation may reduce atherosclerosis. Salvia miltiorrhiza Bunge is a Chinese herb widely used for the treatment of atherosclerosis-related disorders. Salvianolic acid B (Sal B), a water-soluble polyphenolic antioxidant isolated from the roots of this plant, was found to scavenge 1,1-diphenyl-2-picrylhydrazyl radicals and inhibit LDL oxidation more effectively than probucol. In order to evaluate the antiatherogenic potential, New Zealand White rabbits were fed for 12 weeks a normal diet, a high cholesterol diet, a high cholesterol diet containing 1% probucol, or a high cholesterol diet containing a 5% water-soluble extract of S miltiorrhiza (SM). Both SM and probucol feeding reduced plasma cholesterol. LDLs from the SM-treated group were more resistant to Cu 2+ -induced oxidation and contained more vitamin E (21.7±2.1 nmol/μmol LDL cholesterol) than did LDLs from the high cholesterol diet group (9.6±1.8 nmol/μmol LDL cholesterol) ( P <.005). Endothelial damage, determined at week 6, was reduced by 53% in the SM group ( P <.01). SM treatment reduced the atherosclerotic area in the abdominal aorta by 56% ( P <.005) and cholesterol deposition in the thoracic aorta by 50% ( P <.005). The severity of atherosclerosis in the SM group was significantly reduced after adjustment by using cholesterol exposure as an index of the cholesterol-lowering effect. This study concludes that the reduction of atherosclerosis by SM relies not only on its cholesterol-lowering effect but more heavily on its antioxidant potential to prevent endothelial damage and inhibit LDL oxidative modification in hypercholesterolemic animals.