Tocotrienol stmcture

Vitamin E was first described ia 1922 and the name was originally applied to a material found ia vegetable oils. This material was found to be essential for fertility ia tats. It was not until the early 1980s that symptoms of vitamin E deficiency ia humans were recognized. Early work on the natural distribution, isolation, and identification can be attributed to Evans, Butt, and Emerson (University of California) and MattiU and Olcott (University of Iowa). Subsequentiy a group of substances (Eig. 1), which fall iato either the family of tocopherols or tocotrienols, were found to act like vitamin E (1 4). The stmcture of a-tocopherol was determined by degradation studies ia 1938 (5). 

The term vitamin E refers to two groups of compoxmds, the tocopherols and the tocotrienols. The stmctuies of these compoimds appear in Figure 9.90. All forms of the vitamin contain two parts, a "head" and a "tail." The head consists of an aromatic ring stmcture, called chroman or chromanol, and is the site of antioxidant action. The tail of tocopherols is a phytyl group, while the tail of tocotrienols is a polyisoprenoid group. The tail of vitamin E serves to anchor the vitamin in lipid membranes, in the lipids of adipose tissue, and in the lipid surface and core of the lipoproteins. 

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