Study of sphingolipids oxidation by ESI tandem MS

Abstract

Sphingolipids are a class of lipids that play important cellular roles both as structural components of membranes and as signaling molecules. They have also an active participation in apoptosis and inflammation processes which are associated with oxidative stress conditions. However, no studies so far accomplished the oxidative modification of sphingolipids under oxidative stress conditions. In the present study, different sphingolipids, ((d18:1/16:0) sphingomyelin (N-palmitoyl-D-erythrosphingosylphosphorylcholine, SM), (d18:1) sphingosylphosphorylcholine (a lysosphingolipid, SPC), and (d18:1/18:0) ceramide (Cer)) were oxidized by the hydroxyl radical, generated under Fenton reaction conditions, and the oxidation reaction was monitored by ESI-MS in positive mode. No oxidation products were identified for Cer under the oxidative conditions used, while ESI-MS spectra of SPC and SM after oxidation show some oxidation products that were analyzed by ESI-MS/MS. This approach allowed identifying hydroxyl and keto derivatives of SPC and acetaldehydephosphorylcholine derivative (m/z 226). SM oxidation occurs exclusively in sphingosine backbone with formation of SPC, hydroxyl, and keto derivatives of SPC and the oxidation product at m/z 226. This study may give new insight and could help to understanding the behavior and biological roles of the sphingolipids under oxidative stress conditions.

Formation of Oxidatively Modified Lipids as the Basis for a Cellular Epilipidome

“…On the other hand, monounsaturated fatty acyl chains react readily with non-radical oxidants, such as hypochlorous acid (18). In sphingomyelins, the sphingosine moiety appears to be the main site of modification, at least by hydroxyl radicals, reflecting the presence of a C-C double bond (19). Likewise, in cholesterol the mono-unsaturated B ring is readily oxidized, although enzymatic oxidation of the tail also occurs (20)(21)(22).…”

“…Carotenoids contain conjugated polyunsaturated chains and are also highly susceptible to oxidative attack; carotene oxidation products reported include cyclized hydroxy- and keto-containing as well as aldehydes resulting from chain cleavage ( 44 , 45 ). Oxidation of sphingosylphosphorylcholine has been observed to form hydroxyl and keto derivatives on the sphingosine chain ( 19 ).…”

Sphingolipids: promising lipid-class molecules with potential applications for industry. A review

“…On the other hand, sphingomyelin, subjected to hydroxyl radicals generated during Fenton reaction, can be hydrolyzed at its N-acyl linkage into sphingosylphosphorylcholine, with its further conversion into hydroxyl and ketone products. Oxidized sphingolipids may play an important role during development of clinical diseases (Melo et al, 2012). Treatment of various sphingolipids with hypochlorous acid (HOCl), resulted in the formation of mono-and dichloramine-derivatives of sphingolipids, as well as a radical-related decomposition product: hexadecenal, possessing a wide spectrum of biologi- (Shadyro et al, 2015).…”

Sphingomyelins Prevent Propagation of Lipid Peroxidation—LC-MS/MS Evaluation of Inhibition Mechanisms

“…Despite high SMs abundance in some tissues and intracellular compartments, only few studies addressed their oxidation products [28,29]. The lack of the data on SM oxidation is partially explainable by the fact that the main SMs detected in nature are saturated, and consequently not a primary target of oxidation.…”