INFLUENCE OF VITAMIN-E ON PHOSPHATIDYLETHANOLAMINE LIPID POLYMORPHISM

The effect of vitamin E, in its major form α-tocopherol and its synthetic analog α-tocopheryl acetate, on phosphatidylethanolamine lipid polymorphism has been studied by mean of differential scanning calorimetry and 31P-nuclear magnetic resonance techniques. From the interaction of these tocopherols with dielaidoylphosphatidylethanolamine it is concluded that both molecules promote the formation of the hexagonal HII phase at temperatures lower than those of the pure phospholipid. When the tocopherols were incorporated in the saturated dimiristoylphosphatidylethanolamine, which has been shown not to undergo bilayer to hexagonal HII phase transition, up to 90°C, they induce the phospholipid to partially organize in hexagonal HII phase. From our experiments it is shown that α-tocopherol is more effective than its analog in promoting HII phase in these systems. It is also shown that, while α-tocopheryl acetate does not significantly perturb the gel to liquid-crystalline phase transition of dimirystoylphosphatidylethanolamine, α-tocopherol does so and more than one peak appears in the calorimetric profile, indicating that lateral phase separations are taking place. © 1990.