A new LC-MS assay for the quantitative analysis of vitamin K metabolites in human urine[S]

• Published in: Journal of lipid research Vol. 60; no. 4; pp. 892 - 899
• Main Authors: McDonald, Matthew G., Yeung, Catherine K., Teitelbaum, Aaron M., Johnson, Amanda L., Fujii, Shinya, Kagechika, Hiroyuki, Rettie, Allan E.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2019; The American Society for Biochemistry and Molecular Biology; Elsevier
• Subjects: Adult; beta-oxidation; Calibration; Chromatography, Liquid; Dietary Supplements; Healthy Volunteers; Humans; liquid chromatography-mass spectrometry; Male; menaquinone; Methods; Molecular Structure; omega-oxidation; phylloquinone; Tandem Mass Spectrometry; Vitamin K - administration & dosage; Vitamin K - metabolism; Vitamin K - urine; phylloquinone; omega-oxidation; beta-oxidation; liquid chromatography-mass spectrometry; menaquinone
• ISSN: 0022-2275; 1539-7262
• DOI: 10.1194/jlr.D087916

Vitamin K (VK), in both its phylloquinone and menaquinone forms, has been hypothesized to undergo ω- and β-oxidation on its hydrophobic side chain in order to generate the observed urinary metabolites, K acid I and K acid II, which are excreted primarily as glucuronide conjugates. Synthetic standards of K acid I, K acid II, and a putative intermediate metabolite, menaquinone (MK)1 ω-COOH, were used to develop and optimize a new atmospheric pressure negative chemical ionization LC-MS/MS assay for the quantitation of these compounds in urine from untreated individuals and subjects treated with a high dose VK supplement. VK catabolites were extracted from urine, deconjugated, and converted to their methyl ester derivatives using previously reported methodology. The assay showed a high degree of sensitivity, with limits of detection below 10–50 fmol of metabolite per milliliter of urine, as well as an inter-assay precision of 8–12%. Metabolite standards provided unambiguous evidence for MK1 ω-COOH as a new human urinary metabolite of VK. This assay provides a minimally invasive, highly sensitive, and specific alternative for monitoring VK status in humans.