Nachweis maskierter, langkettiger α-Hydroxyaldehyde in Säugetiergewebe-Lipiden

Increase of aldehydic compounds derived from plasmalogens in the brain of aged cattle

The content of plasmalogens in bovine brain was investigated with respect to age. No difference between the plasmalogen content in brain of young and old individuals was detected. In old individuals, plasmalogens suffer much easier hydrolysis to corresponding aldehydes than in young ones. In addition, the brain of old animals contain an approx. 30-fold higher amount of free aldehydes and plasmalogen epoxides compared to young ones. Aldehydes, as well as derived alpha-hydroxyaldehydes, were trapped by addition of pentafluorobenzylaminehydrochloride. The resulting pentafluorobenzyloxime derivatives were enriched by thin-layer chromatography, transferred to trimethylsilyl derivatives and further investigated by GC/MS. Quantification was achieved by GC/FID as well as by GC/ECD.

Plasmalogens and their oxidative degradation products in low and high density lipoprotein

The kinetics of the autoxidation reaction of LDL and HDL with Fe2+/ascorbate was investigated. Aldehydes derived from plasmalogens were determined by conversion to 2-alkyl-1,3-dithiolanes. Their oxidation products, 2-hydroxy-aldehydes, were trapped by reaction with pentafluorobenzylhydroxylamine. After derivatisation, the pentafluorobenzyloximes could be separated from other compounds by thin-layer chromatograpy. They were detected by gas chromatography applying an electron capture detector. LDL plasmalogens are oxidized nearly completely after 180 min while HDL plasmalogens suffer oxidation only to 5%. Oxidation of linoleic and arachidonic acid was investigated by simultaneous determination of 2-hydroxyheptanal.

Detection of short-chain alpha-hydroxyaldehydic compounds as pentafluorbenzyloxime derivatives in bovine liver

Pentafluorbenzyloxime derivatization allows fast, gentle and unambiguous identification of alpha-hydroxyaldehydic lipid peroxidation products via GC/MS in biological material. Even 1.5 g of a bovine liver sample is sufficient to detect short-chain 2-hydroxyalkanales resulting from cleavage reactions of dioxygenated fatty acids. Quantification is achieved after secondary derivatization with N-methyl-N-t-butyldimethylsilyltrifluoracetamide (M-t-BSTFA) by mass spectrometry using characteristic ion traces of the derivatives. In addition, the corresponding (n-1)-hydroxy-n-oxo acids, previously unknown in biological material, could be detected.

Plasmalogen oxidation in human serum lipoproteins

The content of plasmalogens in lipoproteins--very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL)--in human serum was determined and compared with that after oxidation of the lipoproteins. Similarly, the content of alpha-hydroxyaldehydes produced from plasmalogens via their epoxids during lipidperoxidation (LPO) was studied. Incubation with Fe+ +/ascorbate results in a dramatic decrease in plasmalogens that correlates with an appropriate increase in alpha-hydroxyaldehydes. VLDL and LDL plasmalogens were oxidized to a greater extend (99% decrease) compared to HDL plasmalogens (35%). This finding is discussed with respect to atherogenesis and the recently postulated protective qualities of plasmalogens.

Reinvestigation of lipid peroxidation of linolenic acid

Recently, we deduced a mechanism for lipid peroxidation of linoleic acid [1]. This mechanism was now applied to predict the occurrence of previously unknown lipid peroxidation products of linolenic acid. The proposed structures of peroxidation products allowed to search for these predicted compounds in reaction mixtures with the aid of 'ion trace' by mass spectrometry. Thus, a great number of previously unknown lipid peroxidation products was detected. It is assumed that these compounds also occur--at least as intermediates--in lipid peroxidation processes in mammalian tissue.