Effects of excess nicotinamide administration on the urinary excretion of nicotinamide N-oxide and nicotinuric acid by rats.
We investigated a useful chemical index for an excessive nicotinamide intake and how this excessive nicotinamide intake affects the tryptophan-nicotinamide metabolism in rats. Weaning rats were fed on a tryptophan-limited and nicotinic acid-free diet containing no, 0.003%, 0.1%, 0.2%, or 0.3% nicotinamide for 21 days. Urine samples were collected on the last day and analyzed the intermediates and metabolites on the tryptophan-nicotinamide pathway. Nicotinamide N-oxide, nicotinic acid and nicotinuric acid, metabolites of nicotinamide, were detected when nicotinamide at more than 0.1% had been taken. An intake of nicotinamide of more than 0.1% increased the urinary excretion of quinolinic acid, an intermediate on the pathway. Nicotinamide N-oxide and nicotinuric acid increased with increasing dietary concentration of nicotinamide. These results show that the measurements of nicotinamide N-oxide and nicotinuric acid in urine would be useful indices for an excessive nicotinamide intake.
Fukuwatari
Tsutomu
T
Laboratory of Food Science and Nutrition, Department of Life Style Studies, School of Human Cultures, The University of Shiga Prefecture, Hikone, Shiga, Japan. fukkie@shc.usp.ac.jp
Wada
Hideko
H
Sasaki
Ryuzo
R
Shibata
Katsumi
K
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009243:NAD / Q000097:blood / Q000378:metabolism; D009249:NADP / Q000097:blood / Q000378:metabolism; D009536:Niacinamide / Q000008:administration & dosage* / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics / Q000652:urine*; D009539:Nicotinic Acids / Q000652:urine*; D011237:Predictive Value of Tests; D017378:Quinolinic Acid / Q000652:urine; D051381:Rats; D017208:Rats, Wistar; D014364:Tryptophan / Q000378:metabolism; D014886:Weaning; D015430:Weight Gain / Q000187:drug effects
D009539:Nicotinic Acids; D009243:NAD; D009536:Niacinamide; D009249:NADP; C037645:nicotinamide N-oxide; C002477:nicotinuric acid; D014364:Tryptophan; D017378:Quinolinic Acid