Effects of Protein-Free Diet Feeding or Starving on the Excretion Ratio of (N^1-Methyl-2-pyridone-5-carboxamide + N^1-Methyl-4-pyridone-3-carboxamide)/N^1-Methylnicotinamide(Food & Nutrition)

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We have reported that the excretion ratio of nicotinamide metabolites, [N^1-methyl-2-pyridone-5-carboxamide (2-Py)+N^1-methyl-4-pyridone-3-carboxamide(4-Py)]/N^1-methylnicotinamide (MNA), is used as an index of amino acid adequacy. In this experiment, effects of protein-free diet feeding or starving on this excretion ratio were investigated using rats. The experimental period was 10 days. The urinary excretion of MNA, which is a major metabolites of nicotinic acid and nicotinamide, greatly increased with days, however, the urinary excretion of the MNA metabolites, 2-Py and 4-Py, decreased when rats were fed with a protein-free diet for 10 days. Accordingly, the resulting excretion ratio of (2-Py+4-Py)/MNA in rats fed with the protein-free diet greatly decreased compared with that in rats fed with the 20% casein diet (control) (control vs. protein-free diet groups was 21.0±3.5 vs. 0.5±0.1 in urine samples on day 9-10). The urinary excretion of MNA did not increase when rats were starved for 10 days compared with that of the control. However, (2-Py+-4-Py)/MNA decreased to 3.6+0.5 in urine samples on day 9-10. This decrease in the excretion ratio was attributed to the decrease in the activity of 2-Py- and 4-Py-forming MNA oxidase. These results further strengthen our claim that (2-Py+4-Py)/MNA can be used as an index of amino acid adequacy.
社団法人日本農芸化学会の論文
1991-06-23