Influence of cholesterol on the kinetics of lipid autoxidation and on the antioxidative properties of alpha-tocopherol and quercetin

摘要

The autoxidation kinetics of triacylglycerols of sunflower oil (TGSO) in the presence of 10% cholesterol (Chol) at 80,90 and 100 deg C has been studied.The process was followed by monitoring the peroxide value and the formation of conjugated dienes.Cholesterol has been found to exhibit a prooxidative effect.During the oxidation of the mixture (TGSO/Chol),cholesterol peroxides were not registered.It is supposed that the initial amount of cholesterol peroxides formed decomposes to free radicals and that these radicals accelerate TGSO oxidation.A kinetic analysis of the antioxidative behavior of a-tocopherol and quercetin (2.9 x 10~(-4)-17.8 x 10~(-4) M) in both TGSO and TGSO/Chol at 100 deg C was performed.It was found that the effectiveness,strength,and activity of a-tocopherol are greater in TGSO/Chol than in TGSO,while these parameters for quercetin are practically the same in both lipid systems.The differences in the mechanism of action of alpha-tocopherol and quercetin are discussed.