He polar head of these polar lipids [44,135?37]. The typical MS/MS spectrum of [M + H]+ ions of the betaine lipids shows product ions at m/z 236, which is considered the diagnostic product ion of this class and corresponds to the product ion generated from cleavage of both FAs ( 10 H22 O5 N+ ) [136,138]. The MS/MS spectrum of [M + Na]+ adducts also shows the ions at m/z 236 [135,136,139] and ions formed due to the characteristics of NL of 87 Da ( H2 CH2 N+ (CH3 )3 ) [136,140], NL of 74 Da ( H2 N+ (CH3 )3 ) [140] and NL of 59 Da (N+ (CH3 )3 ) [140]. DGCC is easily detected by the dominant product ion m/z 104 [139]. The MS/MS fragmentation fingerprint data of each polar lipid class, which is summarized in Table 2, is important to define specific mass spectral detection of lipid classes. This can also be used to define specific shotgun lipidomic approaches. The presence of specific fragmentation patterns characteristic of each polar lipid class has turned precursor ion scan and neutral loss scan on powerful techniques for the identification and quantification of lipids. The multiple reaction monitoring approach, usually performed in triple quadruple spectrometers, is a target MS analysis that screens a specific parent ion/fragment ion pairs. This approach is commonly used to quantify compounds, usually using the addition of an internal standard per lipid class [141]. 4.4. Highlights of Mass Spectrometry-Based Lipidomics in Marine Macrophytes This section briefly highlights the applications of lipidomics conducted with LC-MS or shotgun lipidomics to study marine macrophytes, summarized in Table 3. The lipidome profile from marine macrophytes can provide a better understanding of the relation between distinct lipid trans-4-Hydroxytamoxifen web species and their potential biological activity. ESI-MS-based shotgun lipidomic analysis has been applied by Kumari et al. in the analysis of polar lipids to monitor lipidomic alterations at the individual lipid class level promoted by different nitrate and phosphate regimes or deprivation in Ulva lactuca [47]. Vu et al. [142] developed the direct infusion electrospray triple quadrupole MS method for studying oxylipin signatures in different stress responses in Arabidopsis thaliana. Nylund et al. [143] applied this oxylipin analysis methodology in the lipid extract from Gracilaria vermiculophylla, while Kumari et al. employed this approach to screen Gracilaria dura [144]. Ma et al. [145] profiled the molecular species of Sargassum horneri using RPLC-MS/MS. They identified 10 MGDG molecular species NecrosulfonamideMedChemExpress Necrosulfonamide mainly represented by C14 and C16 saturated FAs and C18 and C16 unsaturated FA moieties. Furthermore, the authors stated that glycolipids from S. horneri introduced new chemical structures type of MGDGs with 18:2 that reduced the levels of TGs and FAs in adipocytes [145]. Lipidomics LC-MS approaches using HILIC coupled to MS were successfully applied to decode the lipidome of the red macroalgae Chondrus crispus by Melo et al. [37] and Codium tomentosum by da Costa et al. [68] (Table 3). Lipidomic analysis of Chondrus crispus allowed for the identification of 10 distinct classes of lipids and more than 180 molecular species [37]. HILIC-MS analysis of the lipid extract of Codium tomentosum showed the presence of over two hundred species from 12 lipid classes, which correspond to GLs (SQDG, SQMG, MGDG and DGDG), glycerophospholipids (PC, LPC, PI, PA PG and LPG) and di- and monoacyl betaine lipids. SQMG, PI and some species of monoacyl betai.He polar head of these polar lipids [44,135?37]. The typical MS/MS spectrum of [M + H]+ ions of the betaine lipids shows product ions at m/z 236, which is considered the diagnostic product ion of this class and corresponds to the product ion generated from cleavage of both FAs ( 10 H22 O5 N+ ) [136,138]. The MS/MS spectrum of [M + Na]+ adducts also shows the ions at m/z 236 [135,136,139] and ions formed due to the characteristics of NL of 87 Da ( H2 CH2 N+ (CH3 )3 ) [136,140], NL of 74 Da ( H2 N+ (CH3 )3 ) [140] and NL of 59 Da (N+ (CH3 )3 ) [140]. DGCC is easily detected by the dominant product ion m/z 104 [139]. The MS/MS fragmentation fingerprint data of each polar lipid class, which is summarized in Table 2, is important to define specific mass spectral detection of lipid classes. This can also be used to define specific shotgun lipidomic approaches. The presence of specific fragmentation patterns characteristic of each polar lipid class has turned precursor ion scan and neutral loss scan on powerful techniques for the identification and quantification of lipids. The multiple reaction monitoring approach, usually performed in triple quadruple spectrometers, is a target MS analysis that screens a specific parent ion/fragment ion pairs. This approach is commonly used to quantify compounds, usually using the addition of an internal standard per lipid class [141]. 4.4. Highlights of Mass Spectrometry-Based Lipidomics in Marine Macrophytes This section briefly highlights the applications of lipidomics conducted with LC-MS or shotgun lipidomics to study marine macrophytes, summarized in Table 3. The lipidome profile from marine macrophytes can provide a better understanding of the relation between distinct lipid species and their potential biological activity. ESI-MS-based shotgun lipidomic analysis has been applied by Kumari et al. in the analysis of polar lipids to monitor lipidomic alterations at the individual lipid class level promoted by different nitrate and phosphate regimes or deprivation in Ulva lactuca [47]. Vu et al. [142] developed the direct infusion electrospray triple quadrupole MS method for studying oxylipin signatures in different stress responses in Arabidopsis thaliana. Nylund et al. [143] applied this oxylipin analysis methodology in the lipid extract from Gracilaria vermiculophylla, while Kumari et al. employed this approach to screen Gracilaria dura [144]. Ma et al. [145] profiled the molecular species of Sargassum horneri using RPLC-MS/MS. They identified 10 MGDG molecular species mainly represented by C14 and C16 saturated FAs and C18 and C16 unsaturated FA moieties. Furthermore, the authors stated that glycolipids from S. horneri introduced new chemical structures type of MGDGs with 18:2 that reduced the levels of TGs and FAs in adipocytes [145]. Lipidomics LC-MS approaches using HILIC coupled to MS were successfully applied to decode the lipidome of the red macroalgae Chondrus crispus by Melo et al. [37] and Codium tomentosum by da Costa et al. [68] (Table 3). Lipidomic analysis of Chondrus crispus allowed for the identification of 10 distinct classes of lipids and more than 180 molecular species [37]. HILIC-MS analysis of the lipid extract of Codium tomentosum showed the presence of over two hundred species from 12 lipid classes, which correspond to GLs (SQDG, SQMG, MGDG and DGDG), glycerophospholipids (PC, LPC, PI, PA PG and LPG) and di- and monoacyl betaine lipids. SQMG, PI and some species of monoacyl betai.
