Showing papers by "Mitsuo Namiki published in 1982"

Isolation and identification of an antioxidant product from the reaction mixture of dehydroascorbic acid with tryptophan.

Abstract: Several substances with antioxidant activity were isolated from the mixture of dehydroascorbic acid and tryptophan when reacted together in ethanol. One of the main antioxidant products was obtained in crystalline form from an n-butanol extract of the reaction mixture by means of Sephadex column chromatography followed by HPLC with a reversed phase column. 1H- and 13C-NMR of the product and its acetate showed its structure as a condensate of dehydroascorbic acid and tryptophan with each single molecule involving a C-spiro structure. By a POV test the activity of this substance was about two-thirds of that of BHA on a molar basis, and the activity of the reaction mixture is greatly attributable to this substance.