Direct separation of the diastereomers of phosphatidylcholine hydroperoxide bearing 13-hydroperoxy-9Z,11E-octadecadienoic acid using chiral stationary phase high-performance liquid chromatography

Abstract

Increasing evidence suggests that phospholipid peroxidation plays important roles in the pathogenesis of various diseases, such as atherosclerosis. With regard to the biochemical processes that initiate phospholipid peroxidation in vivo, enzymatic conversion of phosphatidylcholine to phosphatidylcholine hydroperoxide (PCOOH) by lipoxygenase (LOX) may play a crucial role. This will become clear if we can analyze PCOOH bearing hydroperoxy fatty acids with S-stereoconfiguration. In this study, we therefore attempted such an analysis. Initially, we used LOX, linoleic acid and Lyso phosphatidylcholine, and synthesized PCOOH bearing 13S-hydroperoxy-9Z,11E-octadecadienoic acid (13(S)-9Z,11E-HPODE). PCOOH bearing racemic 13-9Z,11E-HPODE was also prepared. We used liquid chromatography equipped with CHIRALPAK OP (+) (poly (o-pyridyl diphenylmethacrylate) coated on silica), a UV detector and a quadrupole-time-of-flight mass spectrometer, and achieved diastereomer separation of PCOOH stereoisomers with excellent resolution and peak shape. This is the first study reporting the diastereomer separation of PCOOH. The present method will be beneficial in developing a better understanding of the biochemical processes that initiate oxidative stress (PCOOH formation) in vivo, which may lead to further elucidation of the involvement of PCOOH in the development of diseases. In addition to clinical applications, the present method may also be effective in the evaluation of enzymatic oxidative food deterioration.

Keywords: Chiral stationary phase; Diastereomer; Diastereomer separation; HPLC-Q-TOF/MS; Phosphatidylcholine hydroperoxide.