Production of aliphatic aldehydes on peroxidation of various types of lipids

IN vitro peroxidation by air, or xanthine-xanthine oxidase (xanthine-XOD) was performed to estimate the production of aliphatic aldehydes from free polyunsaturated fatty acids (PUFA), triglycerides, phospholipids and rat liver microsomes and mitochondria. The aldehyde contents in peroxidized lipids were determined by liquid chromatography and fluorescence detection. In both peroxidation, pentanal, (E)-4-hydroxy-2-nonenal (4-HN), and hexanal were produced from omega-6 PUFA rich lipids and propanal was markedly enhanced by increasing the degree of fatty acid unsaturation. The ratios of 4-HN to hexanal production in xanthine-XOD peroxidation of the omega-6 PUFA rich lipids, and rat liver microsomes and mitochondria were much higher than those in air peroxidation. The ratios (4-HN/hexanal) obtained in microsomes and mitochondria by xanthine-XOD were similar to those in rat liver observed in vitamin E deficient studies. The determination of these aldehydes may be useful to estimate the kinds of fatty acids peroxidized and investigate in vivo lipid peroxidation mechanism.