The Fate of Folic Acid and Related Compounds in the Rat


The physiological disposition and metabolism of : folates was studied by purification, characterisation and specific radioactivity determinations of compounds derived from oral doses of labelled folates. At doses of 22 and 320ug of pteroyl-L-glutamic acid/ kg, 50 and 25% respectively was absorbed, With doses of 320ug of [214-C]pteroyl-L-glutamic acid/kg, radioactivity was detected in the peripheral circulation 10 minutes after administration. Pteroyl-L-glutemic acid was absorbed without metabolism and was present in systemic blood for up to 4 hours after administration. With doses of pteroyl-L-glutamic acid from 3.1 to 56ug/kg approximately 6% of the dose was excreted in 24 hours; whilst at 320ug/kg 30% was excreted mainly in the 2 to 4 hour period. Three urinary folates were isolated. One sf the major metabolites was 5-methyltetrahydro-pteroylglutamic acid. The others were unidentified but were not pteroylglutamic acid, 7,8-dihydro-, 5,6,7,8-tetrahydro-, 5- or 10-formyltetrahydro-, 5,10~methylidyne-tetrahydro-, 5,formimidoyltetrahydro-, 5,10-methylene-tetrahydro-, 5-methyltetrahydro-pteroylglutamic acid, nor any decomposition products of these compounds formed during isolation. Labelled unconjugated pteridines were absent. Six hours after administration of pteroyl-L-glutamic acid, more than seven labelled compounds were isolated from liver homogenates. Extractions performed up to 10 days after administration or after prior starvation only conjugates, 5-methyltetrahydro~pteroylglutamate was the major monoglutamate and represented 10% of the total hepatic folates. The physiological disposition of the natural diastereoisomer of 5-methyltetrahydro-pteroylglutamate was similar to that of pteroylglutamate. At a dose of 84u¢/keg, 80% of the urinary folates was 5-methyltetrahydropteroylglutamate, but at lower doses a greater proportion was present as metabolites. The major unidentified metabolite excreted after pteroylglutamic acid administration showed a similar absorption and excretion pattern to 5-methyltetrahydropteroylglutamic acid and was metabolised to 5-methyltetrahydro-pteroylgiutamate. The results are discussed with reference to the nutritional, metabolic and clinical importance of folates in previous work.

Divisions: College of Engineering & Physical Sciences > School of Infrastructure and Sustainable Engineering > Chemical Engineering & Applied Chemistry
Additional Information: Copyright © Dransfield, 1972. E. Dransfield asserts their moral right to be identified as the author of this thesis. This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without appropriate permission or acknowledgement. If you have discovered material in Aston Publications Explorer which is unlawful e.g. breaches copyright, (either yours or that of a third party) or any other law, including but not limited to those relating to patent, trademark, confidentiality, data protection, obscenity, defamation, libel, then please read our Takedown Policy and contact the service immediately.
Institution: Aston University
Uncontrolled Keywords: folic acid,related compounds,rat
Last Modified: 08 Dec 2023 08:01
Date Deposited: 13 Jan 2011 11:34
Completed Date: 1972
Authors: Dransfield, Eric

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