科研之友
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摘要
ANIMAL and human studies have shown that the biological activity of vitamin E sources is dependent on their particular stereochemistry and chemical form (Ingold and others 1987, Ferslew and others 1993, Acuff and others 1994, Kiyose and others 1995). The two most common commercial sources of vitamin E are natural analogues (d- or RRR-a-tocopherol) and synthetic derivatives (dl- or all-rac-atocopherol) with their corresponding stabilised acetate esters. Usually, synthetic vitamin sources are, for the most part, equal in efficacy and structure to the natural source of that vitamin; however, this is not the case for vitamin E (Burton and others 1998). The source of vitamin E with the highest biological activity is natural a-tocopherol that has been isolated from seed oils. Synthetic vitamin E is made from petrochemicals. The difference between natural and synthetic vitamin E is their chemical structures. Natural vitamin E contains one isomer, RRR-a-tocopherol, which has eight different forms; these are alpha-, beta-, gamma- and 8-tocopherols and alpha-, gamma- and delta-tocotrienols. Many different tocopherol and tocotrienol derivatives have been synthesised, but these are most commonly based on racemic a-tocopherol, which contains equimolar amounts of eight stereoisomers, with only one being identical to the natural RRR-isomer. Synthetic vitamin E contains equimolar amounts of eight stereoisomers, of which one is identical to the natural RRR-isomer. The body preferentially transports and incorporates the natural isomer, thereby making the bioavailability of synthetic vitamin E less than that of natural vitamin E (Acuff and others 1994, Burton and others 1998).
- 出版日期2010-3-20
