A new method for the analysis of urinary vitamin E metabolites and the tentative identification of a novel group of compounds.
There is currently interest in measuring urinary metabolites of vitamin E. It has been suggested that alpha-to-copheronolactone (alphaTL), with an oxidized chroman ring, may be an indicator of in vivo oxidative stress and 2,5,7,8-tetramethyl-2(2'-carboxyethyl)-6-hydroxychroman (alpha-CEHC), with a shortened side chain but intact hydroxychroman ring, may provide a measure of adequate or excess vitamin E status. To date, methods in the literature have tended to concentrate on the estimation of single metabolites. We describe the establishment and validation of a relatively simple and reproducible method to extract and quantitate a range of vitamin E metabolites using 0.5 ml of human urine. The vitamin E metabolites were extracted from urine using solid phase extraction cartridges, deconjugated enzymatically, and analyzed using gas chromatography-mass spectrometry. Using this method we have identified alphaTL and the CEHC metabolites derived from alpha-, delta-, and gamma-tocopherol. In addition we have tentatively identified a novel group of vitamin E metabolites, which are related to the CEHCs but have three extra carbons in the side chain. The possibility of the artifactual oxidation of alpha-CEHC to alphaTL during the assay procedure is also discussed.
Pope
S A
SA
Biochemistry, Endocrinology and Metabolism Unit, Institute of Child Health, University College London, United Kingdom.
Clayton
P T
PT
Muller
D P
DP
D000818:Animals; D002839:Chromans / Q000652:urine; D003903:Deuterium; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008722:Methods; D018384:Oxidative Stress; D011422:Propionates / Q000652:urine; D051381:Rats; D015203:Reproducibility of Results; D014810:Vitamin E / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism / Q000652:urine*
D002839:Chromans; D011422:Propionates; D014810:Vitamin E; C034599:tocopheronolactone; C084852:2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman; D003903:Deuterium