Abstract
After tryptophan was administrated orally to riboflavin-deficient rats or to normal rats three types of riboflavin (free form, FMN and FAD) were injected subcutaneusly respectively and the urinary excretion of anthranilic acid, xanthurenic acid, N-methyl nicotinamide and kynurenine were investigated. In normal rats any appreciable difference was hardly found. While, in riboflavin-deficient rats that were fed tryptophan only, a considerable amount of anthranilic acid, xanthurenic acid, and of small amount of N-methylnicotinamide were observed in the urine, while kynurenine was not changed. When tryptophan and riboflavin were administrated, the following results were obtained. Urinary anthranilic acid was not changed by the injection of free type of riboflavin, decreased by FAD, considerably decreased by FMN. A decrease was observed in xanthurenic acid excretion with free riboflavin and FAD, while FMN was unchanged. N-methylnicotinamide was increased by free riboflavin and FAD, and remarkably increased by FMN. Kynurenine was not changed.
