Effects of Vitamin E and Volatile Oils on the Susceptibility of Low-Density Lipoprotein to Oxidative Modification

Antioxidant consumption has been reported to be inversely associated with the incidence of coronary artery disease. To clarify the possible role of vitamin E and volatile oils in the prevention of atherosclerosis, the effects of these compounds on the susceptibility of low-density lipoprotein (LDL) to oxidative modification were investigated. In this study, vitamin E and seven volatile oils “anethol, eugenol, geraniol, limonene, linalool, pulegone and thymol” were added to plasma and incubated at 37°C for 3 h. The LDL fraction was separated by ultracentrifugation and the oxidizability of LDL was estimated by measuring conjugated diene (CD), lipid peroxides and thiobarbituric acid-reactive substances (TBARS) after cupric sulfate solution was added. The data show that vitamin E, thymol and eugenol significantly and dose-dependently prolonged the lag time before initiation of oxidation reaction (P<0.01 by ANOVA). Also, vitamin E and thymol suppressed the formation of lipid peroxides and TBARS more markedly than other volatile oils. The ability to prolong lag time, suppression of lipid peroxides and TBARS formation was in the following order: vitamin E > thymol > eugenol > geraniol > linalool > limonene > anethol > pulegone. These data clearly show that LDL exposed to vitamin E and volatile oils in vitro reduces oxidizability therefore have favorable effects in ameliorating atherosclerosis