Protection by vitamin E, selenium, and beta-carotene against oxidative damage in rat liver slices and homogenate.

Male Sprague-Dawley (SD) rats were fed a vitamin E and selenium deficient diet and diets supplemented with vitamin E, selenium, beta-carotene, and a combination of the three. Tissue slices and homogenate of liver were incubated at 37 degrees C with and without the presence of prooxidants. The effect of vitamin E, selenium, beta-carotene, and the combination of the three antioxidants on the oxidative damage to rat liver tissue was studied by measuring the production of oxidized heme proteins in both tissue slices and homogenate during spontaneous and prooxidant-induced oxidation. The diet with the combination of all three antioxidants showed a strong protective effect against oxidative damage to heme proteins in contrast to the antioxidant-deficient diet. In general, diets with vitamin E, selenium, and beta-carotene were less effective than the combination of all three antioxidants. The protective effect of antioxidants on the heme protein oxidation was correlated with their inhibitory effect on lipid peroxidation measured as the production of thiobarbituric acid-reactive substance (TBARS). The protection of antioxidants on heme proteins was also dependent on the type of oxidation inducer. Possible mechanisms of antioxidants against oxidation in liver tissues are discussed.