Autoxidation rates of 5‐olefinic monoenoic and denoic fatty acids from sea urchin lipids and meadoefoam oils

Abstract

AbstractAutoxidation rates of the 5‐olefinic monoenoic and dienoic fatty acids from sea urchin lipids and meadow‐foam oils were compared with those of normal monoenoic and dienoic fatty acids by gas‐liquid Chromatographic determination of the unoxidized fatty acid methyl esters remaining through the autoxidation period. The fatty acids are classified into five groups shown below according to the oxidation rate of their methyl esters: I 5‐olefinic monoenoic acids (c5‐18:l, c5‐20:l and c5‐22:1), II normal monoenoic acids (c9‐18:l, cll‐18:l, c9‐20:1, cl3‐20:l and cl3‐22:l), III 5‐olefinic dienoic acids (c5,cll‐20:2, c5,cl3‐20:2 and c5,cl3‐22:2), IV 7‐olefinic dienoic acids (c7,cl3‐22:2 and c7,cl5‐22:2) and V normal dienoic acids (c6,c9‐18:2, c9,cl2‐18:2 and cll,cl4‐20:2). The oxidation rates of these groups increased during autoxidation in order from I to V. These results show that the 5‐olefinic monoenoic and dienoic acids are more stable to autoxidation than the normal monoenoic and dienoic acids, respectively. The higher stabilities of the 5‐olefinic monoenoic and dienoic acids in organisms are shown from these results.