Lipid degradation products capable of reacting with amino acid - Identification of 4-hydroxy-2-hexenal, 9-formyl methyl-8-nonenoate, and 10-formyl methyl-9-decenoate from autoxidized methyl linolenate.

Gel chromatography of autoxidized methyl linolenate on Bio-Beads S-X3 gave a degradation product fraction which was discolored by shaking with 0.5M Gly at 45°C for 90 min. IR spectra obtained before and after the discoloration reaction, showed that the absorptions at 5.96 μ due to C=O of conjugated carbonyl, 6.13 μ due to conjugated C=C and 10.3 μ due to trans C=C were remarkably reduced by the discoloration reaction. After conversion of carbonyl group into dimethylhydrazone and of hydroxyl group into TMS ether, the degradation products were analyzed by GLC and GC-MS. Some of conjugated carbonyls that decreased after the discoloration reaction were identified as 4-hydroxy-2-hexenal, 9-formyl methyl-8-nonenoate and 10-formyl methyl-9-decenoate.