Urine 3-hydroxykynurenine is higher during the postovulatory phase than in the preovulatory phase indicating a higher vitamin B₆ requirement

Abstract

The relationship between l-tryptophan to nicotinamide metabolism and the menstrual cycle of Japanese women was investigated. Nine metabolism intermediates from urine samples collected during the preovulatory and postovulatory phases were measured. Only urine 3-hydroxykynurenine was higher in the postovulatory phase than in the preovulatory phase. This increase in 3-hydroxykynurenine suggests a decreased reaction of 3-hydroxykynurenine → 3-hydroxyanthranilic acid catalyzed by kynureninase, a vitamin B₆ enzyme.

Key words:

• menstrual cycle
• nicotinamide
• ovulatory phase
• tryptophan
• vitamin B₆

Funding

This study was part of the “Studies on the nutritional evaluation of amino acids and B-group vitamins” (Principal Investigator, Katsumi Shibata). Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science supported this study.

Notes

Abbreviations: ACMS, α-amino-β-carboxymuconate-ε-semialdehyde; ACMSD, α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase; AMS, α-aminomuconate-ε-semialdehyde; AnA, anthranilic acid; 3-HA, 3-hydroxyanthranilic acid; 3-HK, 3-hydroxykynurenine; HPLC, high-performance liquid chromatography; KA, kynurenic acid; MNA, N¹-methylnicotinamide; 2-Py, N¹-methyl-2-pyridone-5-carboxamide; 4-Py, N¹-methyl-4-pyridone-3-carboxamide; Nam, nicotinamide; Trp, tryptophan; XA, xanthurenic acid.