1. Chemical and physical properties of vitamin E
Domina Petric, MD

2. Essential features of the chemical structure are:
Side-chain derivative of a methylated 6-chromanol nucleus (3,4-dihydro-2H-1-benzopyran-6-ol).
Side chain consists of three isoprenoid units joined head to tail.
Free hydroxyl or ester linkage on C-6 of the chromanol nucleus.
11/15/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

3. Chemical structures of the vitamin E group:
Tocopherols
Tocotrienols
11/15/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

4. Vitamin E nomenclature
Vitamin E is the generic descriptor for all tocol and tocotrienol derivatives that exhibit qualitatively the biological activity of α-tocopherol.
These compounds are isoprenoid side- chain derivatives of 6-chromanol.
11/15/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

5. Vitamin E nomenclature
The term tocol is the trivial designation for the derivative with a side chain consisting of three fully saturated isopentyl units.
Tocopherol denotes generically the mono-, di- and trimethyl tocols regardless of biological activity.
Tocotrienol is the trivial designation of the 6-chromanol derivative with a similar side chain containing three double bonds.
11/15/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

6. Vitamin E nomenclature
Because the tocopherol side chain contains two chiral center carbons (C-4′, C-8′) in addition to the one at the point of its attachment to the nucleus (C-2), eight stereoisomers are possible.
Only one stereoisomer occurs naturally: the R, 9R, R form.
11/15/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

7. Chemical and physical properties
The tocopherols are light yellow oils at room temperature.
They are insoluble in water but are readily soluble in nonpolar solvents.
Tocopherols are good quenchers of free radicals and thus serve as antioxidants.
11/15/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

8. Chemical and physical properties
Tocopherols are easily oxidized and can be destroyed by peroxides, ozone and permanganate in a process catalyzed by light, and accelerated by polyunsaturated fatty acids and metal salts.
They are very resistant to acids and (only under anaerobic conditions) to bases.
11/15/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

9. Chemical and physical properties
Tocopheryl esters, by virtue of the blocking of the C-6 hydroxyl group, are very stable in air and are the forms of choice as food/feed supplements.
Because tocopherol is liberated by the saponification of its esters, extraction and isolation of vitamin E call for the use of protective antioxidants (propyl gallate, ascorbic acid), metal chelators, inert gas environments and subdued light.
11/15/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

10. Chemical and physical properties
The UV absorption spectra of tocopherols and their acetates in ethanol have maxima of 280–300 nm (α-tocopherol, 292 nm).
11/15/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

11. Vitamin E biopotency The most biopotent is the trimethylated (α) form.
11/15/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

12. Literature
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc
11/15/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc