Tocopherol metabolites 2, 5, 7, 8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman (alpha-CEHC) and 2, 7, 8-trimethyl-2-(2'-carboxyethyl)-6-hydroxychroman (gamma-CEHC) in human serum after a single dose of natural vitamin E.
BACKGROUND
alpha- and gamma-Tocopherol are vitamin E compounds in human blood and tissues. alpha-CEHC (2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman) and gamma-CEHC (2,7,8-trimethyl-2-(2'-carboxyethyl)-6-hydroxychroman) have been identified as water-soluble metabolites which are excreted with the urine in humans.


OBJECTIVE
To assess over-time changes of serum levels of alpha- and gamma-CEHC in humans after a single dose of vitamin E from a natural source.


METHODS
Twenty-one healthy subjects ingested a single dose of vitamin E (306 mg of RRR-alpha-tocopherol and 1.77 mg of gamma-tocopherol). Blood was collected before (baseline) and 2, 6, 12, 24, 35, 50, and 74 h after ingestion. Serum was separated and levels of alpha- and gamma-tocopherol and alpha- and gamma-CEHC were determined by HPLC.


RESULTS
After vitamin E ingestion, a statistically significant increase was observed for alpha-tocopherol and alpha-CEHC. Maximum serum levels for both compounds were measured 12 h after application (33.3 +/- 11.1 micromol alpha-toco-pherol /L and 42.4 +/- 18.3 nmol alpha-CEHC /L); baseline values were reached again after 72 h. While gamma-tocopherol levels decreased during the study period, an increase in the metabolite gamma-CEHC was observed. The optical isomer formed in the metabolism of RRR-alpha-tocopherol was assigned as S-alpha-CEHC.


CONCLUSIONS
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.
Radosavac
Dragan
D
Institute of Physiological Chemistry I, Heinrich-Heine University, P. O. Box 101007, 40001 Düsseldorf, Germany.
Graf
Peter
P
Polidori
M Cristina
MC
Sies
Helmut
H
Stahl
Wilhelm
W
D000328:Adult; D001682:Biological Availability; D002839:Chromans / Q000097:blood*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D007536:Isomerism; D008297:Male; D011422:Propionates / Q000097:blood*; D024505:Tocopherols / Q000097:blood* / Q000378:metabolism; D014810:Vitamin E / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D024502:alpha-Tocopherol / Q000097:blood / Q000378:metabolism; D024504:gamma-Tocopherol / Q000097:blood / Q000378:metabolism
D002839:Chromans; D011422:Propionates; D014810:Vitamin E; C107690:2,7,8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman; C084852:2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman; D024504:gamma-Tocopherol; D024502:alpha-Tocopherol; D024505:Tocopherols