Effect of the Addition of Free Tryptophan to a 20% Casein Diet on the Ratio of N^1-Methyl-2-pyridone-5-carboxamide plus N^1-Methyl-4-pyridone-3-carboxamide to N^1-Methylnicotinamide Excretion(Food & Nutrition)

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The effect of the addition of 0.26% free tryptophan (Trp) to a 20% casein diet containing 6mg of nicotinic acid per 100g of diet on the ratio of N^1-methyl-2-pyridone-5-carboxamide (2-py) plus N^1-methyl-4-pyridone-3-carboxamide (4-py) to N^1-methylnicotinamide (MNA) excretion was investigated in rats. The urinary excretion of MNA, 2-py and 4-py, respectively, increased statistically significantly with the feeding of a 0.26% Trp (the same as the content of the 20% casein diet) supplemented 20% casein diet, although it did not increase with the feeding of a 40% casein diet, compared with in the case of the 20% casein diet [Agric. Biol. Chem., 52, 1765 (1988)]. So, the total urinary excretion of Nam and its metabolites was 1.8 times higher in the group fed the Trp supplemented diet than in the group fed the 20% casein diet. However, the ratio of 2-py plus 4-py to MNA excretion was much lower in the group fed the Trp supplemented diet than in the group fed the 20% casein diet (13.16±3.75→5.49±2.25). This decreased ratio was considered to be partially due to a decrease in the 4-py forming MNA oxidase, which decreased significantly with the feeding of the Trp supplemented diet. Furthermore, the metabolic fate of Trp was greatly affected by the form of Trp, free or bound.
社団法人日本農芸化学会の論文
1989-09-23