Lower plasma α-carboxyethyl-hydroxychroman after deuterium-labeled α-tocopherol supplementation suggests decreased vitamin E metabolism in smokers
| Autor: | Jun Li, Scott W Leonard, Richard S. Bruno, Tammy M Bray, Maret G. Traber |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Adult
medicine.medical_specialty Antioxidant Metabolite medicine.medical_treatment alpha-Tocopherol Medicine (miscellaneous) Alpha (ethology) medicine.disease_cause Antioxidants chemistry.chemical_compound Internal medicine Blood plasma medicine Humans Tocopherol Chromans Nutrition and Dietetics Vitamin E Smoking food and beverages Stereoisomerism Metabolism Oxidative Stress Endocrinology chemistry Oxidative stress |
| Zdroj: | The American Journal of Clinical Nutrition. 81:1052-1059 |
| ISSN: | 0002-9165 |
| DOI: | 10.1093/ajcn/81.5.1052 |
| Popis: | BACKGROUND Cigarette smoking increases the fractional disappearance rates of alpha-tocopherol and is associated with increased oxidative stress, but its effects on alpha-tocopherol metabolism are unknown. OBJECTIVE We hypothesized that smokers would have less alpha-tocopherol available and consequently lower plasma alpha-carboxyethyl-hydroxychroman (alpha-CEHC), the alpha-tocopherol metabolite produced by a cytochrome P450-mediated process. DESIGN Smokers and nonsmokers (n = 10 per group) were supplemented with deuterium-labeled alpha-tocopheryl acetates (75 mg each d3-RRR-alpha-tocopheryl and d6-all-rac-alpha-tocopheryl acetate) from day -6 to day -1, and plasma tocopherols and CEHCs were measured (day -6 through day 17). RESULTS After 6 d of supplementation, plasma d3- and d6-alpha-tocopherol concentrations did not differ significantly between groups. Plasma d3- and d6-alpha-CEHCs were detectable only from day -5 to day 5. Before supplementation, unlabeled alpha- and gamma-CEHCs were approximately 60% and 40% lower, respectively, in smokers than in nonsmokers (P < or = 0.05). In addition, d0-, d3-, and d6-alpha-CEHC areas under the curves were approximately 50% lower in smokers (P < 0.05), and smokers had lower maximal d3-alpha-CEHC (P = 0.004) and d6-alpha-CEHC (P = 0.0006) concentrations. Notably, 2.9-4.7 times as much alpha-CEHC was produced from all-rac-alpha-tocopherol than from RRR-alpha-tocopherol. During supplementation, smokers had about one-half (P < 0.05) the plasma total, d6-, or d3-alpha-CEHC concentrations that nonsmokers did given similar alpha-tocopherol concentrations. CONCLUSIONS Smoking did not increase alpha-tocopherol disappearance through P450-mediated tocopherol metabolism. Therefore, the mechanism of increased alpha-tocopherol disappearance in smokers likely operates through oxidation pathways, which is consistent with alpha-tocopherol's antioxidant function. Consequently, evaluating the molecular mechanism or mechanisms responsible for tocopherol metabolism under conditions of oxidative stress and the mechanisms that regulate alpha-tocopherol status is warranted. |
| Databáze: | OpenAIRE |
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