Autoxidation of tissue lipids. II. Monocarbonyl compounds formed by the autoxidation of methyl eicosapentaenoate, methyl docosahexaenoate, and cod-liver oil.

Fatty acid analysis of autoxidized cod-liver oil with a peroxide value of 192 showed significant degradation of only eicosapentaenoic, docosapentaenoic, and docosahexaenoic acids of the linolenate family. Purified, mildly autoxidized cod-liver oil with a peroxide value of 28, methyl eicosapentaenoate, and methyl docosahexaenoate produced carbonyl patterns in agreement with the accepted mechanism for olefinic autoxidation. In all cases the major products were propanal andn-pent-2-enal as predicted, andn-hex-2-enal andn-hept-2-enal as reported in the literature for linolenate. In addition, the same cod-liver oil, which had been heated to 188C in vacuum for 1 hr to decompose completely the hydroperoxides before carbonyl analysis, showed the presence ofn-hepta-2,4-dienal as predicted.