An Effect of Selenium and Cystine on Lipide Peroxidation in Tissues Deficient in Vitamin E

Abstract

TWO vitamin E deficiency syndromes in the chick are preventable by nutrients other than α-tocopherol. Exudative diathesis does not occur when the deficient diet contains trace amounts of selenium. With diets simultaneously low in tocopherol and sulphur amino-acids, muscular dystrophy occurs which can be prevented by cystine, methionine, or vitamin E; trace amounts of selenium (<0.5 p.p.m.) are ineffective. The mechanism by which selenium and sulphur amino-acids replace vitamin E is unknown. Since the only established biochemical action of tocopherol is that of an antioxidant, it appeared that possibly these other nutrients may in some way affect peroxidation of unsaturated fatty acids. Thiobarbituric acid has been shown to be a sensitive reagent for determining the extent of peroxidation in autoxidizing tissues^1,2. Using this test as described by Tappel and Zalkin², we have found that dietary selenium and cystine significantly reduce peroxidation in certain tissues of vitamin E-deficient chicks.