Association of one‐carbon and tryptophan metabolites with vitamin B‐6 concentrations in oral contraceptive users (827.7)

Abstract

Vitamin B‐6 in the form of pyridoxal 5’‐phosphate (PLP) serves as a coenzyme in 1C metabolism and tryptophan (trp) catabolism. In 1C metabolism, PLP acts a coenzyme for serine hydroxymethyltransferase and glycine decarboxylase (glycine‐cleavage system) involved in the provision of 1C units, as well as for the transsulfuration enzymes, cystathionine β‐synthase and cystathionine γ‐lyase. In trp catabolism, PLP is a cofactor for kynureninase and kynurenine aminotransferase. Associations between plasma PLP and changes in metabolites involved in these pathways have previously been reported. We investigated the associations between plasma PLP with 1C and trp metabolites in 165 oral contraceptive users (20‐40 y) from Gainesville, Florida. Plasma concentrations of PLP, homocysteine, cysteine, cysteinylglycine and glutathione were measured by HPLC. Plasma concentrations of other major 1C and trp metabolites were measured by LC‐MS/MS. Associations of PLP concentrations (14.4‐189 nmol/l) with 1C metabolite concentrations were explored by Pearson’s product‐moment correlation. Preliminary data showed a weak negative association of PLP with homocysteine, a moderate negative association of PLP with glutathione (P < 0.05), and a weak positive association of PLP with cysteine and cysteinylglycine concentrations, separately (P < 0.05).Grant Funding Source: Supported by NIH Grant DK072398 and NIH CTSA grant 1UL1RR029890.