Tocopherol metabolites 2, 5, 7, 8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman (α-CEHC) and 2, 7, 8-trimethyl-2-(2'-carboxyethyl)-6-hydroxychroman (γ-CEHC) in human serum after a single dose of natural vitamin E

Radosavac, Dragan; Gräf, Peter; Polidori, Maria Cristina; Sies, Helmut; Stahl, Wilhelm

doi:10.1007/s00394-002-0365-3

Cited by 30 publications

(19 citation statements)

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“…When urinary ␣ -CEHC was initially suggested as a biomarker of adequate vitamin E status, the methodology at that time was not suffi ciently sensitive to detect low urinary levels of ␣ -CEHC excreted during times of vitamin E intake only from diet, although plasma ␣ -CEHC increases were reported with supplemental vitamin E intake ( 109,161 ). Refi nements in methodology have shown that low levels of ␣ -CEHC are continuously excreted in urine and do increase with higher ␣ -tocopherol intake (162)(163)(164).…”

Section: Cehc As a Biomarker Of Vitamin E Statusmentioning

confidence: 99%

Mechanisms for the prevention of vitamin E excess

Traber

2013

Journal of Lipid Research

116

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Section: Cehc As a Biomarker Of Vitamin E Statusmentioning

confidence: 99%

Mechanisms for the prevention of vitamin E excess

Traber

2013

Journal of Lipid Research

116

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“…Although use of g-tocopherol as a supplement has attracted attention, its metabolism in humans is not clearly understood. Radosavac et al (2002) investigated the plasma levels of tocopherols and CEHCs after ingestion of a single dose of vitamin E (306 mg of RRR-a-tocopherol and 1.77 mg of g-tocopherol) and found a significant increase in serum a-tocopherol and a-CEHC levels. Although the g-tocopherol level decreased in their study, an increase in its metabolite g-CEHC was observed (Radosavac et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

“…Radosavac et al (2002) investigated the plasma levels of tocopherols and CEHCs after ingestion of a single dose of vitamin E (306 mg of RRR-a-tocopherol and 1.77 mg of g-tocopherol) and found a significant increase in serum a-tocopherol and a-CEHC levels. Although the g-tocopherol level decreased in their study, an increase in its metabolite g-CEHC was observed (Radosavac et al, 2002). We previously investigated the serum and urine levels of a-and g-CEHC in humans, and reported the elevation of both a-and g-CEHC after high-dose a-tocopherol administration.…”

Section: Introductionmentioning

confidence: 99%

The effect of γ-tocopherol administration on α-tocopherol levels and metabolism in humans

et al. 2005

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Background: The bioavailability of g-tocopherol and metabolites of vitamin E after g-tocopherol administration is not well understood. We investigated the effect of g-tocopherol administration on the levels and metabolism of a-and g-tocopherol in healthy volunteers. Methods: We measured two metabolites of vitamin E (2,5,7,8-tetramethyl-2-(2 0 -carboxyethyl)-6-hydroxychroman (a-CEHC) and 2,7,8-trimethyl-2-(2 0 -carboxyethyl)-6-hydroxychroman (g-CEHC)) in plasma and urine by high-performance liquid chromatography with electrochemical detection (HPLC-ECD) during administration of g-tocopherol. Two groups of volunteers were enrolled. The g-tocopherol group received two g-tocopherol capsules (each containing 186.4 mg of g-tocopherol and 5 mg of a-tocopherol) for 28 days, while the control group received d-a-tocopherol at 5 mg/day, which was the same dose as that given to the g-tocopherol group. Blood and urine samples were obtained on days 0, 14, 28, 35, 42, and 56 after the initiation of g-tocopherol administration. Results: The plasma g-tocopherol concentration increased markedly during administration of g-tocopherol and the plasma g-CEHC concentration increased along with that of g-tocopherol. The plasma a-tocopherol concentration decreased significantly during g-tocopherol administration. The plasma concentration of a-CEHC decreased significantly and urinary excretion of a-CEHC tended to increase in the g-tocopherol group. Urinary sodium secretion was significantly increased at 1 week after the cessation of g-tocopherol administration, but there was no significant difference of urine volume between the two groups. Conclusion: Metabolism of a-tocopherol is accelerated and the plasma a-tocopherol concentration is decreased during g-tocopherol administration.

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“…To evaluate in vivo metabolism of tocopherols, metabolite concentrations have been measured in human urine (5,(7)(8)(9)(10)(11)(12)(13), human plasma (5,(13)(14)(15)(16)(17)(18)(19), and rat bile (20,21). Recently, CEHCs have been reported to have potential health benefits (22)(23)(24)(25) as well as antioxidant functions (26,27).…”

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Quantitation of rat liver vitamin E metabolites by LC-MS during high-dose vitamin E administration

Leonard

Gumpricht

Devereaux

et al. 2005

Journal of Lipid Research

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Vitamin E is a term encompassing a group of lipid-soluble, chain-breaking antioxidants that include ␣ -, ␤ -, ␥ -, and ␦ -tocopherol and the corresponding tocotrienols (1). Vitamin E differs from other fat-soluble vitamins in that it is not accumulated in the liver to toxic levels during times of excess intake (1). A high rate of vitamin E metabolism and/or excretion may be important in preventing adverse effects (2), but this hypothesis has not yet been tested. Tocopherols and tocotrienols are not only excreted directly but can be metabolized in the liver by hepatocytes (3-5); other tissues involved in vitamin E metabolism have not been specifically identified.␣ -and ␥ -tocopherols are converted to their respective carboxyethyl hydroxychroman (CEHC) derivatives, ␣ -CEHC [2,5,7,8-tetramethyl-2-(2 Ј -carboxyethyl)-6-hydroxychroman] and ␥ -CEHC [2,7,8-trimethyl-2-(2 Ј -carboxyethyl)-6-hydroxychroman] ( Fig. 1 ). The specific steps involved in vitamin E metabolism have been identified in vitro using HepG2 cells. These steps initially involve -oxidation by cytochrome P450 enzymes followed by ␤ -oxidative degradation (3, 4, 6).To evaluate in vivo metabolism of tocopherols, metabolite concentrations have been measured in human urine (5, 7-13), human plasma (5,(13)(14)(15)(16)(17)(18)(19), and rat bile (20,21). Recently, CEHCs have been reported to have potential health benefits (22-25) as well as antioxidant functions (26,27). These latter functions are questionable because of the extremely low CEHC concentrations in human plasma (14,15,18,22). There have also been discussions of the use of metabolite concentrations found in urine and plasma as indicators of vitamin E status (7,8,14,28,29), but, as this area is still fairly new and evolving, there is no clear evidence to support the use of metabolites as vitamin E status indicators.To our knowledge, there are no reports on tissue metabolite concentrations. Based on tissue culture studies of metabolite formation by hepatocytes (3-5), it is likely that CEHCs are produced in the liver. Therefore, we have deAbbreviations: CEHC, carboxyethyl hydroxychroman; LC-MS, liquid chromatography-mass spectrometry; MDR1, multidrug resistance protein-1; m/z , mass-to-charge ratio; SXR, steroid and xenobiotic receptor; UGT1A1, UDP-glucuronosyltransferase-1A1.

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Tocopherol metabolites 2, 5, 7, 8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman (α-CEHC) and 2, 7, 8-trimethyl-2-(2'-carboxyethyl)-6-hydroxychroman (γ-CEHC) in human serum after a single dose of natural vitamin E

Abstract: alpha-CEHC levels increase after administration of a single dose of natural vitamin E in humans. The appearance of the metabolite in blood parallels that of the parent compound. The gamma-tocopherol analog appears to be metabolized more efficiently than alpha-tocopherol.

Cited by 30 publications

References 6 publications

Mechanisms for the prevention of vitamin E excess

Mechanisms for the prevention of vitamin E excess

The effect of γ-tocopherol administration on α-tocopherol levels and metabolism in humans

Quantitation of rat liver vitamin E metabolites by LC-MS during high-dose vitamin E administration

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