Harrington, DJ;
Soper, R;
Edwards, C;
Savidge, GF;
Hodges, SJ;
Shearer, MJ;
(2005)
Determination of the urinary aglycone metabolites of vitamin K by HPLC with redox-mode electrochemical detection.
The Journal of Lipid Research
, 46
(5)
pp. 1053-1060.
10.1194/jlr.D400033-JLR200.
![[thumbnail of Vit_K_metabs_JLR_2005.pdf]](https://discovery.ucl.ac.uk/style/images/fileicons/application_pdf.png) Preview |
PDF
Vit_K_metabs_JLR_2005.pdf Download (455kB) |
Abstract
We describe a method for the determination of the two major urinary metabolites of vitamin K as the methyl esters of their agyclone structures, 2-methyl-3-(3-3-carboxymethylpropyl)-1,4-naphthoquinone (5C-side-chain metabolite) and 2-methyl-3-(5-carboxy-3-methyl-2-pentenyl)-1,4-naphthoquinone (7C-side-chain metabolite), by HPLC with electrochemical detection (ECD) in the redox mode. Urinary salts were removed by reversed-phase (C18) solid phase extraction (SPE) and the predominately conjugated vitamin K metabolites hydrolysed with methanolic HCl. The resultant carboxylic acid aglycones were quantitatively methylated with diazomethane and fractionated by normal-phase (silica) SPE. Final analysis was by reversed-phase (C18) HPLC with a methanol-aqueous mobile phase. Metabolites were detected by amperometric, oxidative ECD of their quinol forms, which were generated by post-column coulometric reduction at an upstream electrode. The assay gave excellent linearity (r2 typically = 0.999) and high sensitivity with an on-column detection limit of <3.5 fmol (<1pg). The inter-assay precision was typically 10%. Metabolite recovery was compared to that of an internal standard (2-methyl-3-(7'-carboxy-heptyl)-1,4-naphthoquinone), added to urine samples just before analysis. Using this methodology we confirmed that the 5C- and 7C-metabolite were major catabolites of both phylloquinone (vitamin K1) and menaquinones (vitamin K2) in humans. We propose that the measurement of urinary vitamin K metabolite excretion is a candidate non-invasive marker of total vitamin K status.
| Type: | Article |
|---|---|
| Title: | Determination of the urinary aglycone metabolites of vitamin K by HPLC with redox-mode electrochemical detection |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1194/jlr.D400033-JLR200 |
| Additional information: | Imported via OAI, 9:29:00 10th May 2005 |
| UCL classification: | UCL |
| URI: | https://discovery.ucl.ac.uk/id/eprint/348 |
Loading...
Loading...Loading...Loading...Archive Staff Only
 |
View Item |
