A new vitamin E (alpha-tocomonoenol) from eggs of the Pacific salmon Oncorhynchus keta

A novel α-tocomonoenol [3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyl-12-tridecenyl)-2H-1-benzopyran-6-ol] having an unusual methylene unsaturation at the isoprenoid-chain terminus of α-tocopherol was isolated from the lipophilic fraction of chum salmon eggs. The structure of this marine-derived tocopherol (MDT) was established by spectral analyses. The peroxyl radical-trapping activities of MDT and α-tocopherol were compared in aqueous phosphatidylcholine liposomal suspension and in methanolic solution at 37 °C. The antioxidant activity of MDT was found to be identical to that of α-tocopherol under the experimental conditions of measurement.