Formation of α-tocopherol complexes with fatty acids. A hypothetical mechanism of stabilization of biomembranes by vitamin E

Abstract

The formation of α-tocopherol complexes with saturated and unsaturated fatty acids in ethanol has been demonstrated. The values of equilibrium constants for α-tocopherol interactions with fatty acids have been determined. These values do not depend in practice on the number of carbon atoms in saturated fatty acid molecules (from 7:0 to 24:0) and are equal to about 40–50 M −1. For unsaturated fatty acids the values of equilibrium constants are increased exponentially with an increase in the number of double bonds in the fatty acid molecule (1.25 · 10 4 M −1 for arachidonic acid). α-Tocopherol can form complexes with free fatty acids incorporated into phosphatidylcholine liposomes or into skeletal muscle sarcoplasmic reticulum membranes. The formation of α-tocopherol complexes with free fatty acids is regarded as a molecular mechanism of membrane stabilization by vitamin E against the damaging action of free fatty acids.