Membrane stabilizing effect of vitamin E: existence of a hydrogen bond between alpha-tocopherol and phospholipids in bilayer liposomes.

In order to elucidate the existence of a hydrogen bond between alpha-tocopherol and phospholipids in bilayer liposomes, the effects of the presence or absence of alpha-tocopherol or its acetate on either the permeability of liposomes to chromate ions or the fluidity of liposomes composed of the different kinds of lecithin [egg yolk phosphatidylcholine (EPC), 1-oleoyl-2-palmitoylphosphatidylcholine (OPPC), or 1-O-oleyl-2-O-palmitoylphosphatidylcholine (OPPCE)] were examined. From the results obtained, it was concluded that the hydroxyl group of alpha-tocopherol is hydrogen bonded to the carbonyl group of a fatty acid ester in the phospholipids of bilayer liposomes in order to retain alpha-tocopherol molecule in the space close to the surface of membranes formed by the unsaturated fatty acid moiety of phospholipids.