名称:
9-Hydroxy-10,12-octadecadienoic acid (9-HODE) and 13-hydroxy-9,11-octadecadienoic acid (13-HODE): excellent markers for lipid peroxidation
摘要:
Various conditions for conversion of (9S,10E,12Z)-9-hydroperoxy-10,12-octadecadienoic acid (9S-HPODE) and (13S,92,10E)-13-hydroperoxy-9,11-octadecadienoic acid (13S-HPODE) into the corresponding hydroxy acids, (9S,10E,12Z)-9-hydroxy-10,12-octadecadienoic acid (9S-HODE) and (13S,9Z,10E)-13-hydroxy-9,11-octadecadienoic acid (13S-HODE), were investigated in vitro. 9S-HODE and 13S-HODE were subjected to lipid peroxidation under various conditions: oxidation was carried out in air only, and in air/Fe2+/ascorbate, air/H2O2/Fe2+, air/Fe2+, and air/Fe3+. In contrast to the corresponding hydroperoxides (9S-HPODE and 13S-HPODE), 9-HODE and 13-HODE proved to be stable in all these oxidation experiments. Unexpectedly, hydroxy compounds obtained by reduction of hydroperoxides derived from arachidonic acid were not attacked by air/Fe2+/ascorbate or air/Fe2+. Thus, for instance, (15S,5Z,8Z,11Z,13E)-15-hydroxy-5,8,11,13-eicosatetraenoic acid (15-HETE) remained unchanged in spite of possessing the structural prerequisites for attack by radicals, i.e. a CH2-group located between two double bonds. Consequently, metal-induced air oxidation reactions of these systems seem to be restricted to hydroperoxides of unsaturated acids (LOOH) and not to corresponding hydroxy compounds (LOH). The reported experiments explain why hydroxy derivatives of unsaturated acids, especially 9-HODE and 13-HODE, are enriched in naturally occurring lipid peroxidation (LPO) processes to a greater extent than any other LPO product and why they are nearly ideal markers for LPO. (C) 1997 Elsevier Science Ireland Ltd.