[Effect of alpha- and gamma-tocopherol as well as cholesterol on lipid peroxidation]

For a period of 15 weeks growing rats were fed low fat diets containing equimolar doses of alpha- and gamma-tocopherol (180 and 174 ppm) as well as mixtures of alpha- and gamma-tocopherol (3:1; 1:1; 1:3) without cholesterol or with 1% cholesterol. The influence of these supplements on lipid peroxidation and tocopherol retention in the liver were investigated. The tocopherol status was estimated by measuring the activities of creatine kinase and transaminases (GOT, GPT) in plasma as well as by in vitro hemolysis of erythrocytes. The in vitro hemolysis rate was only lowered by alpha-tocopherol and the mixtures of alpha- and gamma-tocopherol. In response to lipid peroxidation in the liver, alpha-tocopherol was the more efficient antioxidant, whereas gamma-tocopherol was more efficient in the diet. Cholesterol had a lowering effect on lipid peroxidation in vitro and in vivo; cholesterol in combination with alpha-tocopherol had a stabilizing effect on the erythrocyte membrane. Moreover, there was a positive effect of cholesterol on tocopherol retention in the liver. The biological activity of gamma-tocopherol in relation to alpha-tocopherol was calculated according to the test criterium; it ranged from 22 to 100%.