Isolation of a trimer of alpha-tocopherol from mammalian liver.

Evidence is presented for the formation in mammalian liver of a trimeric metabolite of alpha-tocopherol. This compound has been shown to be identical to a trimer produced by oxidation of alpha-tocopherol with alkaline K(3)Fe(CN)(6). In addition, confirmation was obtained for the occurrence in vivo of a dimeric metabolite reported previously. These compounds, together with tocopheryl-p-quinone, are postulated to arise from reactions with lipid-free radicals or peroxides in the course of the antioxidant action of vitamin E.