Study note
BiochemistryMicronutrients: Vitamins & Minerals

Vitamin E: membrane functions, vitamer families, and potency

THE CONTEXT
Vitamin E comprises tocopherols and tocotrienols with differing biological potencies; no unequivocal unique metabolic function has been established.

Membrane and signaling functions

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Vitamin E acts as a lipid-soluble antioxidant in cell membranes, where synthetic antioxidants can provide many of its functions.
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It helps maintain cell membrane fluidity and has a relatively poorly defined role in cell signaling.

Families and biological potency

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Vitamin E is the generic descriptor for the tocopherol and tocotrienol families.
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D-α-Tocopherol is the most active vitamer. Intake is usually expressed as milligrams of D-α-tocopherol equivalents.
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Synthetic DL-α-tocopherol does not have the same biological potency as the naturally occurring compound.

Substitution patterns

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In α-tocopherol and α-tocotrienol, R1, R2, and R3 are methyl groups.
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In β-vitamers, R2 is hydrogen; in γ-vitamers, R1 is hydrogen; in δ-vitamers, both R1 and R2 are hydrogen.
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