Effects of Vitamin B6 Deficiency on the Conversion Ratio of Tryptophan to Niacin

• Published in: Bioscience, biotechnology, and biochemistry Vol. 59; no. 11; pp. 2060 - 2063
• Main Authors: Shibata, Katsumi, Mushiage, Masako, Kondo, Takako, Hayakawa, Takashi, Tsuge, Haruhito
• Format: Journal Article
• Language: English
• Published: Tokyo Taylor & Francis 1995; Japan Society for Bioscience Biotechnology and Agrochemistry; Oxford University Press
• Subjects: Animals; Biological and medical sciences; Biotechnology; Diet; Feeding Behavior; Fundamental and applied biological sciences. Psychology; Kynurenic Acid - urine; Metabolisms and neurohumoral controls; Niacin - biosynthesis; Niacinamide - metabolism; Niacinamide - urine; Nitrogen metabolism. Proteins. Glycoproteins. Nucleic acids. Collagen; Rats; Rats, Wistar; Tryptophan - metabolism; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vitamin B 6 Deficiency - metabolism; Vitamin B 6 Deficiency - urine; Weight Gain; Xanthurenates - urine; In vivo; Vertebrata; Mammalia; Deficient diet; Rat; Rodentia; Vitamin; Tryptophan; Vitamin deficiency; Pyridoxine; Metabolism
• ISSN: 0916-8451; 1347-6947
• DOI: 10.1271/bbb.59.2060

To investigate how vitamin B 6 (B 6 ) deficiency affects the whole metabolism of tryptophan-niacin, rats were fed for 19 days with each of the following four kinds of diets; a complete 20% casein diet (control diet), the control diet without B 6 , the control diet without nicotinic acid, and the control diet without nicotinic acid and B 6 , and the urinary excretion of such tryptophan metabolites as kynurenic acid, xanthurenic acid, nicotinamide, N 1 -methylnicotinamide, N 1 -methyl-2-pyridone-5-carboxamide, and N 1 -methyl-4-pyridone3- carboxamide each and the enzyme activities involved in tryptophan-niacin pathway were measured. The urinary excretion of kynurenic acid decreased while that of xanthurenic acid increased drastically in the two B 6 -deficient groups, when compared with the B 6 -containing groups. These results indicate that the rats fed with the B 6 -free diets were in the vitamin-deficient state. The conversion ratio was calculated from the ratio of the urinary excretion of sum of nicotinamide, N 1 -methylnicotinamide, N 1 -methyl-2-pyridone-5carboxamide, and N 1 -methyl-4-pyridone-3-carboxamide, to the Trp intake. The ratio was statistically lower in the B 6 -free diet than in the B 6 -containing diet under the niacin-free conditions.