ANTIOXIDATIVE ACTIVITIES OF ALGAL EXTRACTS, SYNERGISTIC EFFECT WITH VITAMIN-E

The antioxidant effect of seven species of marine algae on the preservation of sunflower oil were investigated by storage experiments at 75°. Laminaria digitata (Kombu) and Himanthalia elongata were the most effective in extending the induction period. Extracts of these two seaweeds were then compared with vitamin E and BHT as regards to their antioxidative activities, by kinetic studies in a model system. The thermal initiated oxidation of methyl linoleate was performed at 60° in heptanol, with or without antioxidants. When they reached 1 % of the substrate, seaweed extracts exhibited antioxidant activities by extending the induction period but they were not actually effective. Effects of the addition of algal extracts together with vitamin E on the preservation of methyl linoleate, sunflower oil or mixed ethyl eicosapentaenoate and docosahexaenoate were investigated at 60° by the same kinetic studies. Algal extracts synergistically enhance the antioxidant effect of vitamin E when the latter is present at a level higher than 1 × 10-4 M. On mechanistic grounds, the understanding of this synergism is outlined. Seaweed extracts should find applications in the cosmetic and food industries without any further purification. © 1990.