Comparison of Low-Density Lipoprotein Oxidation by Hydrophilic O(3 P)-Precursors and Lipid-O(3 P)-Precursor Conjugates.

Abstract

Lipid oxidation by reactive oxygen species (ROS) provide several different oxidation products that have been implicated in inflammatory responses. Ground state atomic oxygen [O(3 P)] is produced by the photodeoxygenation of certain heterocyclic oxides and has a reactivity that is unique from other ROS. Due to the reactive nature of O(3 P), the site of O(3 P)-generation is expected to influence the products in heterogenous solutions or environments. In this work, the oxidation of low-density lipoprotein (LDL) by lipids with covalently bound O(3 P)-photoprecursors was compared to more hydrophilic O(3 P)-photoprecursors. Lipid oxidation products were quantified after Bligh-Dyer extraction and pentafluorobenzyl bromide (PFB) derivatization by GC-MS. Unlike the more hydrophilic O(3 P)-photoprecursors, the oxidation of LDL during the irradiation of lipid-(O3 P)-photoprecursor conjugates showed little quenching by the addition of the O(3 P)-scavenging sodium allyl sulfonate. This indicated that lipophilic O(3 P)-photoprecursors are expected to generate lipid oxidation products where other more hydrophilic O(3 P)-photoprecursors could be quenched by other reactive groups present in solution or the environment.