Antioxidant effect of the reaction mixture of dehydroascorbic acid with tryptophan.

Abstract

Antioxidant activities as measured by the peroxide value, and the thiobarbituric acid or oxygen uptake methods were observed on a reaction mixture of dehydroascorbic acid with tryptophan. This was stronger than any of the activities of similar amino-carbonyl reaction mixtures tested and was comparable to BHA. The strongest activity was developed when an equimolar mixture of the reactants in 95% ethanol were heated for 30 min in a boiling water bath. In the antioxidant action, the presence of α-tocopherol acted synergistically. When the mixture was fractionated by TLC on a cellulose plate a brown colored fraction proved strongly effective by the POV method. Another fraction, effective in the oxygen uptake method but not in the POV method, was found mainly consisting of ascorbic acid. Other fractions which were identified before and related to the free radical formation were all inactive.