Tryptophan metabolism in baboons: effect of riboflavin and pyridoxine deficiency.

Seven urinary metabolites of tryptophan-kynurenine pathway were measured in riboflavin-deficient, pyridoxine-deficient, pair-fed and natural diet baboons. The most significant changes in the pyridoxine-deficient baboons was a mean sevenfold increase in the excretion of xanthurenic acid and a threefold decrease in 3-hydroxy anthranilic acid. The riboflavin-deficient baboons showed a twelvefold increase in the excretion of anthranilic acid, and a tenfold decrease in 3-hydroxy kynurenine. Red blood-cell pyridine nucleotides decreased only in the pyridoxine-deficient baboons, while plasma 11-hydroxy corticosteroids increased only in the riboflavin-deficient baboons. These results are discussed in relation to enzymatic changes that may be expected during these deficiencies.