Tocopherol Content in Edible Plant Oils

Tocol-related compounds, tocopherols and tocotrienols, are important bioactive constituents of vegetable oils. They belong to the family of vitamin E active substances. The term “vitamin E” usually refers to a group of compounds occurring naturally in plants, all deriving from 6-chromanol with a 2-phytyl substituent. Tocopherols are vitamin E compounds with a saturated phytyl chain, while tocotrienols have three double bonds at the positions 3’, 7’, and 11’ of the alkyl side chain. The α-, β-, γ-, δ-tocopherols and tocotrienols are differentiated in function of the number and location of methyl substituents in the chroman ring (Figure 1). Vitamin E is the major lipophilic antioxidant, which is an efficient scavenger of alkoxyl and peroxyl radicals [Wang & Quinn, 1999]. It protects membranes against photoinhibition and other photooxidative stresses in plants. A major physiological role of tocopherols is to prevent lipid peroxidation during seed dormancy, germination and early seedling development [Sattler et al., 2004]. Tocopherols protect humans from the oxidative stress mediated by active oxygen and nitrogen species. The protective role of vitamin E against atherosclerosis, cardiovascular diseases, cataracts, neural tube defects and cancer has been the subject of extensive studies [Azzi & Stocker, 2000]. The important role of vitamin E compounds in food production and commercialization is preventing lipids and lipid-containing foodstuffs from oxidation during storage, thus extending their stability and shelf life. Tocopherols and tocotrienols occur in plants in variable amounts, and their biological and antioxidative activity varies between individual compounds [Saldeen & Saldeen, 2005]. Vegetable oils provide the best source of vitamin E. The strucTOCOPHEROL CONTENT IN EDIBLE PLANT OILS