Structural motifs in primary oxidation products of palmitoyl‐arachidonoyl‐phosphatidylcholines by LC‐MS/MS

Abstract

Oxidative modifications to phospholipids (OxPL) play a major role in modulating signaling events in inflammation and infection, and complete understanding on the induced biological effects can only be understood based on knowledge of the oxidative motifs present. Specific neutral losses observed in tandem mass spectrometry data (LC-MS/MS) of primary peroxidation products in oxidized palmitoyl-arachidonoyl-phosphatidylcholines (OxPAPC) provide information on the prevailing structural motifs regarding the oxidized acyl carbon chain, the nature of oxidized group and the site of carbon oxidation. The higher hydrophobicity of hydroperoxides compared to di-hydroxy derivatives under reverse-phase conditions together with specific fragmentation patterns enabled the identification of 12 structurally different OxPAPC structural (di-hydroxy and hydroperoxide derivatives) and positional isomers as well as the presence of poly-hydroxy together with isoprostanes derivatives. The fragmentation patterns described in quadrupole time-of-flight and linear ion trap instruments complement the m/z value and retention time parameters in the identification of oxidative composition in OxPAPC products becoming a valuable tool for the exploratory screening of oxidized phosphatidylcholines in OxPAPC extracts, distinction of native and modified PC isobaric structures in complex samples contributing to the increased understanding of redox lipidomics in inflammation and infection.

Detection and confirmation of serum lipid biomarkers for preeclampsia using direct infusion mass spectrometry

“…The marker with m/z 798 was predicted to be an oxidized (hydroxylated) PC (16:0/20:4), as indicated by the fragmentation pattern seen, and consistent with other studies ( 37 ). The exposure of PC species to ROS can result in oxidation of the species.…”

“…A fragment ion at m/z 496.3, most likely corresponding to 16:0 fatty acid, was also observed. This fragmentation pattern most likely represents a hydroxylated PC (16:0/20:4), and this agrees with previously published literature ( 37 ). Therefore, marker with m/z 798.6 was predicted to be hydroxylated PC (36:4)+H + .…”

“…Collectively, our study and otherwise commonly observed in the MS 2 spectrum of PCs. This major neutral water loss peak observed for this precursor strongly suggests an easily removable hydroxyl group ( 37 ). A fragment ion at m/z 496.3, most likely corresponding to 16:0 fatty acid, was also observed.…”

Oxidative Lipidomics Coming of Age: Advances in Analysis of Oxidized Phospholipids in Physiology and Pathology

“…Product ion scanning also provides information on diagnostic fragment ions for individual oxidized products, which can subsequently be used in the targeted scanning approaches. Several reviews have described typical fragmentation products and have provided useful summaries of the information (20,99,117). In these LC-MSMS lipidomic approaches to discover oxidized lipids present in complex samples, data-dependent acquisition is often used, whereby throughout the LC run, ions for fragmentation and product ion scanning are selected based on intensity, which is prone to missing low-abundance ions that may be biologically important (Fig.…”

A Targeted Mass Spectrometry Approach to detect and quantify Oxidised Phospholipids in plasma samples of Diabetic patients

“…However, it is analytically impractical to measure oxidised species of all classes in a single run because of variation in charge of polar head group and extreme diversity of oxidised phospholipid species. Various reports describe the combination of either reverse phased and or normal-phase LC coupled with mass spectrometry in multi-dimensional set ups to detect and measure long chain oxidation products (Hui et al, 2010, Reis et al, 2013, Uchikata et al, 2012, Tyurina et al, 2009, Morgan et al, 2010. Our study focus on the detection of oxidised phosphatidylcholines (OxPCs), which represent an abundant class demonstrating variety of biological activities but insufficiently characterised in several inflammatory diseases.…”