Relative bioactivity of dietary RRR- and all-rac-alpha-tocopheryl acetates in swine assessed with deuterium-labeled vitamin E.
This study evaluated the relative bioactivities of natural and synthetic stereoisomers of alpha-tocopherol in swine. Deuterium-labeled vitamin E (150 mg each of d3-RRR- [natural] and d6-all-rac- [synthetic] alpha-tocopheryl acetates) was administered orally to adult female pigs (n = 3) with the morning feed. Blood samples were obtained at 0, 3, 6, 9, 12, 36, 48, and 72 h after the dose. The time of maximum plasma d3-alpha-tocopherol concentration (0.486 microg/mL) occurred at 12 h, and d6-alpha-tocopherol peaked earlier (at 9 h) and at a lower (P < 0.05) concentration (0.288 microg/mL). The d3-/d6-alpha-tocopherol ratio increased from 1.35 (SD = 0.73) at 3 h after dosing to 2.0 (SD = 0.14) at 72 h (P = 0.03). The plasma disappearance rates of d3- and d6-alpha-tocopherols (post-maximum concentrations) were similar and were estimated to be 0.013 microg/mL per hour. In summary, swine discriminated between RRR- and all-rac-alpha-tocopherols, which resulted in an approximately twofold higher plasma alpha-tocopherol concentration arising from the RRR-form. This 2:1 ratio of RRR- to all-rac- is higher than the currently accepted USP definition of RRR-:all-rac- of 1.36:1.00.
Lauridsen
C
C
Department of Animal Nutrition and Physiology, Research Centre Foulum, Tjele, Denmark. charlotte.lauridsen@agrsci.dk
Engel
H
H
Craig
A M
AM
Traber
M G
MG
D000284:Administration, Oral; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000493:pharmacokinetics*; D001682:Biological Availability; D003903:Deuterium; D005260:Female; D013237:Stereoisomerism; D013552:Swine / Q000378:metabolism*; D024505:Tocopherols; D014810:Vitamin E / Q000378:metabolism*; D024502:alpha-Tocopherol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics*
D000975:Antioxidants; D014810:Vitamin E; D003903:Deuterium; D024502:alpha-Tocopherol; D024505:Tocopherols