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Mechanisms of antioxidant interactions in oil-in water emulsions: The influence of their physical locations and environmental pH

Panya A., Kittipongpittaya K., Laguerre M., Bayrasy C., Lecomte J., Villeneuve P., McClements D.J., Decker E.A.. 2013. Inform, 24 (8) : p. 538-541.

A classic example of synergistic antioxidant interactions can be observed between [alpha]-tocopherol (vitamin E) and ascorbic acid (vitamin C) in cell membranes. This synergism is due to "antioxidant regeneration" via the recycling of a stronger (primary) antioxidant with a weaker (secondary) antioxidant. By this principle, the primary antioxidant ([alpha]-tocopherol) scavenges free radicals in the lipid phase and is then regenerated by the secondary antioxidant (ascorbic acid). From a thermodynamic point of view, the reaction is favorable because the reduction potential of ascorbic add is much lower than a-tocopherol, indicating that ascorbic acid prefers to give an electron to oxidized [alpha]-tocopherol. From a physical property viewpoint, this reaction is also favorable because a-tocopherol is in the membrane where it can inactivate lipid radicals and yet is also at the membrane interface where it can react with ascorbic acid.

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