Effect of Adding Branched-chain Amino Acids to a Nicotinic Acid-free, Low-protein Diet on the Conversion Ratio of Tryptophan to Nicotinamide in Rats

Abstract

The effects of adding branched-chain amino acids to a nicotinic acid-free, low-protein diet on the conversion of tryptophan to nicotinamide were investigated in rats. The conversion ratio [urinary excretion of nicotinamide and its metabolites (pmol/day) x 100/ tryptophan intake during urine collection (pmol/day)] was significantly lower in the groups fed with the 3% Leu-, Val-, or lIe-added diet than in the group fed with the control diet. Namely, the inhibition of this conversion was observed not only by the addition of Leu, but also by the addition of Valor lIe. The addition of lIe and/or Val to the Leu-added diet did not antagonize the Leu effect.

Effects of Excess Nicotinamide Administration on the Urinary Excretion of NicotinamideN-Oxide and Nicotinuric Acid by Rats

“…1). Numerous factors such as pregnancy, 7) nutrition, [8][9][10][11][12][13][14][15] hormones, [16][17][18][19][20] chemicals, [21][22][23][24][25][26] and experimental models of diseases [27][28][29] affect this conversion from tryptophan to nicotinamide. However, little is known about the association between the nicotinamide intake and tryptophan-nicotinamide pathway.…”

The Urinary Excretory Ratio of Nicotinamide Catabolites Was Associated with the Conversion Ratio of Tryptophan to Nicotinamide in Growing Rats Fed a Niacin-Free 20% Casein Diet

“…[11][12][13][14][15] Krehl et al 16) found that Trp could completely counteract the growth retardation caused by corn grits diet in rats. The conversion ratio of Trp to Nam is not constant: It is affected by age, 5) various nutritional factors, 10,[17][18][19][20][21][22][23][24][25] hormones, [26][27][28] and chemicals. [29][30][31] Therefore, it is important in preventing a pellagra outbreak to know the conversion ratio of Trp to Nam under the conditions, but it is not possible to know this in case of emergency and conflict.…”

“…Shibata and co-workers 10,[17][18][19][20][21][22]33) found that the urinary excretory ratio of (2-Py + 4-Py)/MNA primarily reflected protein nutritional status, not Nam nutritional status, because the excretory ratio was decreased by the administration of an extremely large amount of Nam 34) and MNA 35) in rats. In addition, Shibata et al 36) reported that the administration of 150 mg/d of Nam did not affect the excretory ratio in humans.…”

Increased Conversion of Tryptophan to Nicotinamide in Rats by Dietary Valproate

“…[3][4][5][6][7] Finding factors affecting the conversion of Trp to Nam is therefore very important for preventing outbreaks of pellagra. The conversion of Trp to Nam is not constant: it is affected by age, 8) various nutritional factors, 1,[9][10][11][12][13][14][15][16][17] hormones, [18][19][20] and chemicals. [21][22][23][24][25][26][27][28][29][30] Shin et al 31) have reported that the administration to rats of peroxisome proliferators increased the liver NAD concentration by inhibiting liver -amino--carboxymuconate-"-semialdehyde decarboxylase (ACMSD).…”