Identification and quantitation of unique fatty acid oxidation products inhuman atherosclerotic plaque using high-performance liquid chromatography

Oxidation of lipoproteins, particularly low-density lipoprotein, is thought to play a major role in the development of atherosclerosis, We set out to identify and quantitate the major fatty acid oxidation products in human at herosclerotic plaque obtained from individuals undergoing carotid endartere ctomy. Oxidized lipids were extracted from plaque homogenate under conditio ns to prevent artifactual oxidation, Identification and quantitation was pe rformed using HPLC and GC-MS, High levels of hydroxyoctadecanoic acids (0.5 1 +/- 0.17 ng/mug of linoleic acid), 15-hydroxyeicosatetranoic acid (HETE) (0.66 +/- 0.24 ng/mug of arachidonic acid), and 11-HETE (0.84 +/- 0.24 ng/m ug of arachidonic acid) were detected in all atherosclerotic plaques (n = 1 0), Low levels of 9-oxo-octadecanoic acid (oxoODE) (0.04 +/- 0.01 ng/mug of linoleic acid), were present in all samples, while 13-oxoODE (0.01 +/- 0.0 08 ng/mug of linoleic acid) was present in only 4 of the 10 plaque samples. Of interest was the identification of two previously unidentified compound s in atherosclerotic plaque, 11-oxo-eicosatetranoic acid in 9 of the 10 sam ples and 5,6-dihydroxyeicosatetranoic acid in 3 samples. Chiral analysis re vealed that all the major compounds identified in this study are of a nonen zymatic origin. This study is the first to provide a convenient HPLC method to quantify all the products of both linoleic acid and arachidonic acid ox idation in human atherosclerotic plaque. The quantitation of lipid peroxida tion products in plaque may be important given the potential biological act ivity of these compounds and their possible relationship to plaque pathogen esis and instability. (C) 2001 Academic Press.