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The metabolism of high intakes of tryptophan, nicotinamide and nicotinic acid in the rat

McCreanor, GM; Bender, DA; (1986) The metabolism of high intakes of tryptophan, nicotinamide and nicotinic acid in the rat. British Journal of Nutrition , 56 (3) 577 - 586. 10.1079/BJN19860138. Green open access

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Abstract

1. The metabolic fate of high dietary intakes of nicotinamide, nicotinic acid and tryptophan, and of acute doses of nicotinamide and nicotinic acid, has been studied in the rat. A new high-pressure liquid chromatography method for measurement of the principal urinary metabolites of niacin is described. 2. Administration to rats of a single oral dose of nicotinamide or nicotinic acid (up to 100 mg/kg body-weight), or maintenance for 3 weeks on diets providing 150 mg nicotinamide or nicotinic acid/kg diet, resulted in only a small increase in the liver content of nicotinamide nucleotide coenzymes (NAD and NADP). The quantitative metabolism of nicotinamide and nicotinic acid differed, suggesting that intestinal bacterial deamidation is not the major fate of nicotinamide. 3. A high dietary intake of tryptophan (5.9 g/kg diet) led to a considerable increase in liver NAD(P) and also in urinary excretion of niacin metabolites. The results suggest that, as indicated by enzyme kinetic studies (Bender et al. 1982), the utilization of nicotinamide and nicotinic acid for nucleotide synthesis is limited, while there is little or no limitation of NAD(P) synthesis from the tryptophan metabolite quinolinic acid.

Type: Article
Title: The metabolism of high intakes of tryptophan, nicotinamide and nicotinic acid in the rat
Open access status: An open access version is available from UCL Discovery
DOI: 10.1079/BJN19860138
Publisher version: http://dx.doi.org/10.1079/BJN19860138
Language: English
Additional information: © 1986 Cambridge University Press
Keywords: Animals, Chromatography, High Pressure Liquid, Male, Niacin, metabolism, pharmacokinetics, Niacinamide, Rats, Inbred Strains, Tryptophan, urine, analysis
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Structural and Molecular Biology
URI: https://discovery.ucl.ac.uk/id/eprint/137500
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