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

<jats:p><jats:italic>Abstract</jats:italic>—Antioxidants that prevent LDL from oxidation may reduce atherosclerosis.<jats:italic>Salvia miltiorrhiza</jats:italic>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<jats:italic>S miltiorrhiza</jats:italic>(SM). Both SM and probucol feeding reduced plasma cholesterol. LDLs from the SM-treated group were more resistant to Cu<jats:sup>2+</jats:sup>-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) (<jats:italic>P</jats:italic><.005). Endothelial damage, determined at week 6, was reduced by 53% in the SM group (<jats:italic>P</jats:italic><.01). SM treatment reduced the atherosclerotic area in the abdominal aorta by 56% (<jats:italic>P</jats:italic><.005) and cholesterol deposition in the thoracic aorta by 50% (<jats:italic>P</jats:italic><.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.</jats:p>