Description
Molecules having vitamin E antioxidant activity include four tocopherols (α, β, δ, and γ) and four tocotrienols (α, β, δ, and γ).
1 α-
Tocopherol is the major lipid soluble antioxidant
in vivo and protects against lipid peroxidation.
2 α-
CEHC is the major urinary metabolite of α-
tocopherol following vitamin E supplementation.
3 The concentration of α-
CEHC in human serum is in the range of 5-
10 pmol/ml but increases significantly up to 200 pmol/ml upon supplementation with RRR-
α-
tocopherol. About one-
third of the α-
CEHC circulating in the blood is present as a glucuronide conjugate.
4 α-
CEHC was only excreted when a threshold concentration of 7-
9 μmol α-
tocopherol/g total lipid in plasma was exceeded. Therefore, excretion of α-
CEHC may be considered to be a marker of optimum vitamin E intake.
5
References
1. Kamal-Eldin, A., and Appelqvist, L.-?.
The chemistry and antioxidant properties of tocopherols and tocotrienols Lipids 31(7),671-701(1996).
2. Burton, G.W., Joyce, A., and Ingold, K.U.
Is vitamin E the only lipid-soluble, chain-breaking antioxidant in human blood plasma and erythrocyte membranes? Arch. Biochem. Biophys. 221(1),281-290(1983).
3. Traber, M.G., Elsner, A., and Brigelius-Flohé, R.
Synthetic as compared with natural vitamin E is preferentially excreted as α-CEHC in human urine: Studies using deuterated α-tocopheryl acetates FEBS Lett. 437,145-148(1998).
4. Stahl, W.S., Graf, P., Brigelius-Flohé, R., et al.
Quantification of the α- and γ-tocopherol metabolites 2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman and 2,7,8-trimethyl-2-(2'-carboxyethyl)-6-hydroxychroman in human serum Anal. Biochem. 275,254-259(1999).
5. Schultz, M., Leist, M., Petrzika, M., et al.
Novel urinary metabolite of α-tocopherol, 2,5,7,8-tetramethyl-2(2'-carboxyethyl)-6-hydroxychroman, as an indicator of an adequate vitamin E supply Am. J. Clin. Nutr. 62(6),1527S-1534S(1995).