Conjugated Carbonyl Compounds with a Hydroxycyclopentanone Ring Formed During Autoxidation of Methyl Docosahexaenoate

Abstract

Conjugated carbonyls with a hydroxycyclopentanone ring were purified from autoxidized methyl docosahexaenoate by gel chromatography on Sephadex LH-20, silicic acid chromatography on Si-10 and HPLC on Resolve Silica. After reduction with NaBH₄ or NaBD₄ and subsequent trimethylsilylation, GC-MS analysis was carried out and carbonyl peaks were monitored by reconstructed ion chromatography using characteristic ions (m/z 167, 191 and 217). From mass spectral analysis of the each peak, two new types of carbonyls, methyl 3- [2- (2-formylvinyl) -3-hydroxy-5-oxocyclope ntyl] propionate and methyl 6- [2- (2-formylvinyl) -3-hydroxy-5-oxocyclopentyl] -4-hexenoate were identified.