Oxidation and anti-oxidation of conjugated trienoic fatty acid methyl ester

Although conjugated fatty acids are paid much attention to their interesting physiological properties such as anticancer, anti-arteriosclerosis, anti-hypertension activities, loss in body fat etc, there is few information on their oxidation behaviors. In the present work, the oxidation behavior of conjugated linolenic acid methyl ester (CLN-Me) was compared with corresponding non-conjugated α-linolenic acid methyl ester (LN-Me) under the various oxidation conditions and the antioxidative activities of some radical scavenging antioxidants, such as tocopherol (Toc), sesamol (SE), propylgallate (PG) and epigallocatechin gallate (EGCG), for CLN-Me were evaluated. Under the oxidation tests at 5, 30 and 150℃, the oxidation behaviors of CLN-Me were shown to be different from those of LN-Me. The CLN-Me was considered to form not only hydroperoxides that is main products of LN-Me but also cyclic peroxides at primary oxidation stage. In thermal oxidation at 150℃, polymerization reaction might be prior to decomposition reaction, owing to form a large quantity of more polymerized products in CLN-Me. The productions of peroxides, decomposition compounds and polymeric compounds from CLN-Me by oxidation were able to be prevented by the addition of Toc, SE, PG and EGCG, and EGCG showed the strongest antioxidant effect for CLN-Me as same as for LN-Me based on the highest radical scavenging ability among these antioxidants