Vitamin E

What is vitamin E?

Vitamin E is a group of fat-soluble vitamers of which different tocopherols and tocotrienols are part, both with forms named α-, β-, γ-, and δ-, according to their common chromane ring chemical structure.

The IUPAC systematic name for α-tocopherol is (2R)-2,5,7,8-tetramethyl-2-[(4R,8R)-4,8,12-trimethyltridecyl]-3,4-dihydrochromen-6-ol. For α-tocotrienol the name is ((2R)-2,5,7,8-tetramethyl-2-[(3E,7E)-4,8,12-trimethyltrideca-3,7,11-trienyl]-3,4-dihydrochromen-6-ol

Chemical structure

All vitamin E vitamers have a chromane ring, which features a hydroxyl group that can donate a hydrogen atom to reduce free radicals and a hydrophobic side chain that allows penetration into biological membranes. The structure of α-tocopherol is shown below.

alpha-tocopherol GVJHHUAWPYXKBD-IEOSBIPESA-N
α-Tocopherol GVJHHUAWPYXKBD-IEOSBIPESA-N
3D structure

The α-tocotrienol differs from α-tocopherol in that it has three double bonds in the side chain as shown in the figure.

alpha-tocotrienol RZFHLOLOLGZPDCHJ-XZXLULOTSA-N
α-Tocotrienol RZFHLOLGZPDCHJ-XZXLULOTSA-N

The nomenclature of α-, β-, γ-, etc for tocopherols and tocotrienols, is used depending on the number and position of the substituents, in the chromane skeleton. The following figure shows the different chromane structures and their numbering.

alpha- beta- chrome numbering

The α-tocopherols and α-tocotrienols have two methyl groups at positions 5 and 7 of the chromane ring. The β- compounds have only one methyl at position 5, and the γ- compounds have only one methyl at position 7. The δ- compounds have no methyl groups at positions 5 and 7.

chromo gamma - delta - chroma gamma - delta numbering

Functions

Vitamin E is a fat-soluble vitamin that has strong antioxidant properties. One of its main tasks is to prevent oxidation, a chemical reaction that can cause illness, disease and other harmful effects. Vitamin E also plays an important role in maintaining the proper functioning of muscles and nerves, aids in the formation of red blood cells, and helps in the utilization of vitamin K.

Vitamin E is a relevant factor in the prevention of heart problems by helping to stop the oxidation of cholesterol in the arteries. It protects against certain types of cancer, relieves fibrocystic breast disease and premenstrual syndrome, and helps maintain metabolic control in diabetes.

Food sources

Avocados, whole grains, dark green leafy vegetables, poultry, eggs, seafood, seeds, nuts, wheat germ, asparagus and various oils (sunflower, almond, wheat germ and hazelnut).

Most people do not get enough vitamin E from their diets.

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