Difference of Antioxidative Effect Between Vitamin E and Selenium

To study antioxidative effects of vitamin E and selenium, two experiments were conducted. Experiment I: To study effects of vitamin E and/or selenium deficiency on malondialdehyde (MDA) levels in tissues and on oxidation of erythrocyte of rat fed with natural deficient diet. Experiment II: To study effects of vitamin E and/or selenium deficiency on MDA levels and free radicals levels in tissues, and on fluidity of erythrocyte membrane of rat fed with semisynthetic diet. It was found that MDA levels in tissues of vitamin E deficient groups were higher than that of selenium deficient groups in both experiments. In contrast to MDA level, free radicals levels detected by ESR in tissues of vitamin E deficient groups were lower than that of selenium deficient groups. Results of oxidation of erythrocyte with oxidants in vitro showed that vitamin E protected against hemolysis of erythrocyte induced by ascorbic acid, whilst selenium protected against oxidation of haemoglobin by superoxide anion. Effects of vitamin E and selenium deficiency on fluidity of erythrocyte membrane estimated by ESR and expressed as rotational correlation time (rc) were also different: vitamin E deficiency increased rc, when fluidity was estimated by labelling with 5-doxy stearic acid or 16-doxy stearic acid. Selenium deficiency increased rc, when fluidity was estimated by labelling with 3-maleimido proxy and 3-(3-maleimidopropyl-carbamyl) proxy. It means that vitamin E deficiency caused decrease of fluidity of erythrocyte membrane due to damage to lipid of membrane and selenium deficiency caused decrease of fluidity of erythrocyte membrane due to damage to -SH group in membrane protein. These results demonstrated that antioxidant action of vitamin E and selenium are different: (1) vitamin E acts on the biomembrane, and selenium acts in the form of Se-dependent glutathione peroxidase (GPX) in cytoplasm; (2) vitamin E prevents lipid peroxidation more effectively than selenium, whereas selenium prevents free radicals production more effectively than vitamin E; (3) vitamin E protects lipid of membrane and selenium protects -SH group in membrane protein against oxidation.