Myeloperoxidase-derived 2-chlorohexadecanal forms Schiff bases with primary amines of ethanolamine glycerophospholipids and lysine.

Numerous studies have suggested relationships between myeloperoxidase, inflammation, and atherosclerosis. MPO-derived reactive chlorinating species (RCS) attack membrane plasmalogens releasing alpha-chloro-fatty aldehydes (alpha-Cl-FALDs) including 2-chlorohexadecanal (2-ClHDA). The molecular targets of alpha-Cl-FALDs are not known. The current study demonstrates 2-ClHDA adducts with ethanolamine glycerophospholipids and Fmoc-lysine. Utilizing electrospray ionization mass spectrometry, chlorinated adducts were observed that are apparent Schiff base adducts. Reduction of these Schiff base adducts with sodium cyanoborohydride resulted in a novel, stable adduct produced by the elimination of HCl. NMR further confirmed this structure. 2-ClHDA adducts with ethanolamine glycerophospholipids were also substrates for phospholipase D (PLD). The hydrolysis products were derivatized to pentafluorobenzoyl esters, and further structurally confirmed by GC-MS. Multiple molecular species of 2-ClHDA-N-modified ethanolamine glycerophospholipids were observed in endothelial cells treated with 2-ClHDA. These results show novel Schiff base adducts of alpha-Cl-FALDs with primary amines, which may represent an important fate of alpha-Cl-FALDs.