ANTIOXIDATIVE ACTIVITY OF LYSINE 13-HYDROPEROXY-9(Z),11(E)-OCTADECADIENOIC ACID REACTION-PRODUCTS/

The antioxidative activity of the reaction products formed in the reac tion between 13-hydroperoxy-9(Z),11(E)-octadecadienoic acid (13-LOOH) and L-lysine was evaluated to determine if the reaction of lipid hydro peroxides with amino acids produces compounds that are able to protect lipids against oxidation. A reaction mixture of 13-LOOH and lysine wa s incubated for 8 days at 37 degrees C and, then, fractionated chromat ographically by using silica cartridges. The four fractions obtained i n this way were added at two levels of concentration (100 and 200 ppm) to soybean oil, which was oxidized under air in the dark at 60 degree s C. Oil peroxidation was evaluated by using the thiobarbituric acid-r eactive substances (TBARS) assay. The less polar fraction obtained, wh ich was eluted with 2-propanol, did not decrease TBARS production in t he soybean oil. However, the other three fractions were able to signif icantly (P < 0.05) reduce TBARS production, suggesting that the reacti on of lipid hydroperoxides with amino acids produces compounds with an tioxidative properties. These reactions may contribute to a decrease o f the lipid peroxidation process in foods containing proteins.