gamma-Tocopherol biokinetics and transformation in humans.

gamma-Tocopherol biokinetics and transformation in humans. Research Abstract Details 

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gamma-Tocopherol biokinetics and transformation in humans. Abstract Text:

Francesco Galli,Rosalind Lee,Jeffrey Atkinson,Ardesio Floridi,Frank J Kelly,

BACKGROUND: The uptake and biotransformation of gamma-tocopherol (gamma-T) in humans is largely unknown. Using a stable isotope method we investigated these aspects of gamma-T biology in healthy volunteers and their response to gamma-T supplementation. METHODS: A single bolus of 100 mg of deuterium labeled gamma-T acetate (d(2)-gamma-TAC, 94% isotopic purity) was administered with a standard meal to 21 healthy subjects. Blood and urine (first morning void) were collected at baseline and a range of time points between 6 and 240 h post-supplemetation. The concentrations of d(2) and d(0)-gamma-T in plasma and its major metabolite 2,7,8-trimethyl-2-(b-carboxyethyl)-6-hydroxychroman (-gamma-CEHC) in plasma and urine were measured by GC-MS. In two subjects, the total urine volume was collected for 72 h post-supplementation. The effects of gamma-T supplementation on alpha-T concentrations in plasma and alpha-T and gamma-T metabolite formation were also assessed by HPLC or GC-MS analysis. RESULTS: At baseline, mean plasma alpha-T concentration was approximately 15 times higher than gamma-T (28.3 vs. 1.9 micromol/l). In contrast, plasma gamma-CEHC concentration (0.191 micromol/l) was 12 fold greater than alpha-CEHC (0.016 micromol/l) while in urine it was 3.5 fold lower (0.82 and 2.87 micromol, respectively) suggesting that the clearance of alpha-CEHC from plasma was more than 40 times that of gamma-CEHC. After d(2)-gamma-TAC administration, the d(2) forms of gamma-T and gamma-CEHC in plasma and urine increased, but with marked inter-individual variability, while the d(0) species were hardly affected. Mean total concentrations of gamma-T and gamma-CEHC in plasma and urine peaked, respectively, between 0-9, 6-12 and 9-24 h post-supplementation with increases over baseline levels of 6-14 fold. All these parameters returned to baseline by 72 h. Following challenge, the total urinary excretion of d(2)-gamma-T equivalents was approximately 7 mg. Baseline levels of gamma-T correlated positively with the post-supplementation rise of (d(0) + d(2)) - gamma - T and gamma-CEHC levels in plasma, but correlated negatively with urinary levels of (d(0) + d(2))-gamma-CEHC. Supplementation with 100 mg gamma-TAC had minimal influence on plasma concentrations of alpha-T and alpha-T-related metabolite formation and excretion. CONCLUSIONS: Ingestion of 100mg of gamma-TAC transiently increases plasma concentrations of gamma-T as it undergoes sustained catabolism to CEHC without markedly influencing the pre-existing plasma pool of gamma-T nor the concentration and metabolism of alpha-T. These pathways appear tightly regulated, most probably to keep high steady-state blood ratios alpha-T to gamma-T and gamma-CEHC to alpha-CEHC.

gamma-Tocopherol biokinetics and transformation in humans. Publishing Authors By Initials

F Galli,R Lee,J Atkinson,A Floridi,FJ Kelly,

For similar heterocyclic compounds: heterocyclic compounds, 2-ring: benzopyrans: vitamin e: tocopherols: gamma-tocopherol research abstracts see: heterocyclic compounds: heterocyclic compounds, 2-ring: benzopyrans: vitamin e: tocopherols: gamma-tocopherol research

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gamma-Tocopherol biokinetics and transformation in humans. Journal Published:

PUBLICATION TYPE: Research Support, Non-U.S. Gov

Journal: Free radical research

VOLUME: 37

Page Numbers: 1225-33

Journal Abbreviation: Free Radic. Res.

ISSN: 1071-5762

DAY: 19

MONTH: Nov

YEAR: 2003

gamma-Tocopherol biokinetics and transformation in humans. Information

Number of References:

LANGUAGE: eng

NlmUniqueID: 9423872

gamma-Tocopherol biokinetics and transformation in humans. Keywords Mesh Terms:

KEYWORDS: gamma-Tocopherol

MESH TERMS: urine

Chemical & Substance for Abstract: gamma-Tocopherol biokinetics and transformation in humans. Information

Substance Name: tocopherol acetate

Registry Number: 7695-91-2

Grant and Affiliation Information for gamma-Tocopherol biokinetics and transformation in humans.

AFFILIATION: Lung Biology, School of Health and Life Sciences, King's College, London, UK. f.galli@unipg.it

Country: England

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MEDLINETA: Free Radic Res

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