Lipidomics of the Edible Brown Alga Wakame (Undaria pinnatifida) by Liquid Chromatography Coupled to Electrospray Ionization and Tandem Mass Spectrometry

Abstract

The lipidome of a brown seaweed commonly known as wakame (Undaria pinnatifida), which is grown and consumed around the world, including Western countries, as a healthy nutraceutical food or supplement, was here extensively examined. The study was focused on the characterization of phospholipids (PL) and glycolipids (GL) by liquid chromatography (LC), either hydrophilic interaction LC (HILIC) or reversed-phase LC (RPLC), coupled to electrospray ionization (ESI) and mass spectrometry (MS), operated both in high and in low-resolution mode. Through the acquisition of single (MS) and tandem (MS/MS) mass spectra more than 200 PL and GL of U. pinnatifida extracts were characterized in terms of lipid class, fatty acyl (FA) chain composition (length and number of unsaturations), and regiochemistry, namely 16 SQDG, 6 SQMG, 12 DGDG, 5 DGMG, 29 PG, 8 LPG, 19 PI, 14 PA, 19 PE, 8 PE, 38 PC, and 27 LPC. The FA (C16:0) was the most abundant saturated acyl chain, whereas the monounsaturated C18:1 and the polyunsaturated C18:2 and C20:4 chains were the prevailing ones. Odd-numbered acyl chains, iJ., C15:0, C17:0, C19:0, and C19:1, were also recognized. While SQDG exhibited the longest and most unsaturated acyl chains, C18:1, C18:2, and C18:3, in the sn-1 position of glycerol, they were preferentially located in the sn-2 position in the case of PL. The developed analytical approach might pave the way to extend lipidomic investigations also for other edible marine algae, thus emphasizing their potential role as a source of bioactive lipids.

Comprehensive Lipidomic Analysis of Three Edible Brown Seaweeds Based on Reversed-Phase Liquid Chromatography Coupled with Quadrupole Time-of-Flight Mass Spectrometry

“…Lipid composition in seaweeds has been investigated in the last decade by lipidomics with the purpose to reveal the healthy benefits and added value attributed to seaweeds. − A widely used method in lipidomic studies is ultra-high-performance liquid chromatography coupled with high-resolution tandem mass spectrometry (UPLC–HRMS) . With the advantage of analyzing both polar and nonpolar metabolites as well as lipids, UPLC–HRMS has been widely used to reveal the polar lipid profiles of several brown seaweed species. ,,, These previous studies have highlighted the wide variety of polar lipid molecules in brown seaweeds, constituted mainly by phospholipids (PLs), glycolipids (GLs), and betaine lipids (BLs), which are the main constituents of cell membranes, thylakoid membranes, and signaling molecules, respectively . Among them, GLs composed of glycoglycerolipids and glycosphingolipids are predominant, accounting for approximately 50% of the total lipid content .…”

Applications of lipidomics in marine organisms: progress, challenges and future perspectives

“…In the case of RP columns, C18 is the most widely used but others can also be used, such as C8 and C30. [30][31][32] Different instruments have been used to address the challenges of marine lipidomics. Low resolution instruments such as Triple Quadrupole and Q-Traps have been mainly used for targeted analysis and Linear Ion Trap for untargeted analysis.…”

“…In the case of RP columns, C18 is the most widely used but others can also be used, such as C8 and C30. 30–32…”

“…Lipid characterization studies of macroalgae using LC-MS were carried out for some macroalgae species from Chlorophyta, 26,58 Rhodophyta 24,59–61 and Ochrophyta phyla (Table S1, ESI†). 32,62,63 These studies characterized the polar lipidome of macroalga species and identified several molecular species of PL, GL, and BL. The chain of FA esterified in the polar lipid species ranged from 14 to 22 carbons and 0 to 6 double bonds.…”

Algal Lipids as Modulators of Skin Disease: A Critical Review

“…They mainly focus on the FA composition and aim to establish a relationship between the FA profile and PUFA abundance with antioxidant activity [70]. Algae extracts are complex mixtures that comprise different classes of lipids, including neutral lipids, such as triacylglycerol (TAG), sterols, free FA; and polar lipids, such as phospholipids, glycolipids, and betaine lipids [73][74][75][76][77]. Recently, it has been suggested that polar lipids such as phospholipids, are better at delivering omega-3 PUFA [78].…”