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α‐ and γ‐tocotrienols are metabolized to carboxyethyl‐hydroxychroman derivatives and excreted in human urine
Author(s) -
Lodge John K.,
Ridlington James,
Leonard Scott,
Vaule Heather,
Traber Maret G.
Publication year - 2001
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-001-0666-z
Subject(s) - urine , vitamin e , tocotrienol , chemistry , urinary system , tocopherol , ingestion , excretion , vitamin , endocrinology , medicine , chromatography , biochemistry , antioxidant
Limited information is available regarding metabolism of vitamin E forms, especially the tocotrienols. Carboxyethyl‐hydroxychromans (α‐and γ‐CEHC) are human urinary metabolites of α‐ and γ‐tocopherols, respectively. To evaluate whether tocotrienols are also metabolized and excreted as urinary CEHC, urine was monitored following tocotrienol supplementation. Complete (24 h) urine collections were obtained for 2 d prior to (baseline), the day of, and 2 d after human subjects ( n =6) ingested tocotrienol supplements. The subjects consumed 125 mg γ‐tocotrienyl acetate the first week, then the next week 500 mg; then 125 mg α‐tocotrienyl acetate was administered the third week, followed by 500 mg the fourth week. Urinary α‐ and γ‐CEHC were measured by high‐performance liquid chromatography with electrochemical detection. Urinary γ‐CEHC levels rose about four‐ to sixfold in response to the two doses of γ‐tocotrienol and then returned to baseline the following day. Significant ( P <0.0001) increases in urinary α‐CEHC were observed only following ingestion of 500 mg α‐tocotrienyl acetate. Typically, 1–2% of α‐tocotrienyl acetates or 4–6% of γ‐tocotrienyl acetates were recovered as their respective urinary CEHC metabolites. A γ‐CEHC excretion time course showed an increase in urinary γ‐CEHC at 6 h and a peak at 9 h following ingestion of 125 mg γ‐tocotrienyl acetate. In summary, tocotrienols, like tocopherols, are metabolized to CEHC; however, the quantities excreted in human urine are small in relation to dose size.