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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.

The chain-breaking (peroxyl radical-trapping) antioxidant activity of plasma obtained from several patients with a very severe vitamin E deficiency has been measured. The total chain-breaking antioxidant activity in lipid extracts has been shown to be approximately equal to the concentration of vitamin E. For whole plasma there is no significant difference in the concentrations of water-soluble, chain-breaking antioxidants between the E-deficient patients and healthy adults. It is concluded that even in cases of very severe vitamin E deficiency the requirement for this vitamin is not met by some other exogenous or endogenous antioxidant.