Investigating the formation of eicosanoids and other oxylipins by means of LC-MS/MS (QqQ)

Prof. Dr. Nils Helge Schebb

Chair of Food Chemistry, University of Wuppertal, Faculty of Mathematics and Natural Sciences, 42119 Wuppertal, Germany

Lipid mediators play an important role in biology. Particularly eicosanoids (C20) and oxidative products of other long chain polyunsaturated fatty acids (PUFA) regulate a large variety of cellular and physiological functions, e.g. in inflammation or proliferation. In mammals, these oxylipins are formed enzymatically via three pathways: i) constitutively expressed cyclooxygenase 1 (COX-1) and inducible COX-2, ii) 5-, 12- and 15-lipoxygenases (LOX) as well as iii) cytochrome P450 monooxygenases (CYP) and non-enzymatically by (aut)oxidation. The initially formed products can be further converted by several other enzymes, for example by microsomal prostaglandin E synthase (mPGES) or by soluble epoxide hydrolase (sEH) leading to a pleiotropy of oxylipins formed in the arachidonic acid (AA) cascade.

Robust and reliable quantification of eicosanoids and other oxylipins in biological samples is crucial for a better understanding of their biology and to monitor the effects of diet or pharmacological interventions on the AA cascade. Low (sub-nanomolar) concentrations and a large number of structurally similar analytes, including regioisomers, require high chromatographic resolution and selective as well as sensitive MS analysis. Currently, reversed phase LC in combination with detection on sensitive triple quadrupole instruments, operating in selected reaction monitoring (SRM) mode, is dominantly used for quantitative oxylipin analysis. Firstly, the challenges for quantitative analysis by means of LC-QqQ-MS are summarized. 
In the second section of the talk, quantitative oxylipin analysis is applied to the investigation to the analysis of effects of n3-PUFA supplementation. 

Literature:
Anal Chim Acta,2018, 1037, 63-74. 
Front. Pharmacol, 2019, 10:169.
Prostag Oth Lipid M.,2020, 146, 106384
Free Radical Biology & Medicine, 2019 144, 72-89 (Review)
J Lipid Research, 2020, 61, 1424 – 1436

Prof. Dr. Nils Helge Schebb (Food Chemist and European Registered Toxicologist) is full professor for food chemistry at the University of Wuppertal, Germany. His group is developing instrumental analytical methods to investigate the biological activity of food ingredients. 
The major focus of his research group in the last decade is set on targeted lipidomics of oxylipins. His lab developed one the most comprehensive internationally validated platforms for the analysis of oxylipins. Using this approach, the effect how n3-PUFA as well as polyphenols elicit their beneficial effects on human health, are analyzed. Dr. Schebb has published >100 peer reviewed publications of those > 50 about the analysis, formation and biology of oxylipins.