tocopherol A collective name for a group of closely related lipids that contain a chroman-6-ol nucleus substituted at position 2 by a methyl group and by a saturated hydrocarbon chain consisting of three isoprenoid units. They are designated as α-, β-, γ-, and δ-tocopherol depending on the number and position of additional methyl substituents on the aromatic ring. Tocopherols occur in vegetable oils and vegetable oil products, almost exclusively with <i>R</i>,<i>R</i>,<i>R</i> configuration. Tocotrienols differ from tocopherols only in having three double bonds in the hydrocarbon chain. CHEBI:27013 tocol