The demand for sustainable and environmentally friendly food sources and food ingredients is increasing, and microalgae are promoted as a sustainable source of essential and bioactive lipids, with high levels of omega-3 fatty acids (ω-3 FA), comparable to those of fish. However, most FA screening studies on algae are scattered or use different methodologies, preventing a true comparison of its content between microalgae. In this work, we used gas-chromatography mass-spectrometry (GC-MS) to characterize the FA profile of seven different commercial microalgae with biotechnological applications (Chlorella vulgaris, Chlorococcum amblystomatis, Scenedesmus obliquus, Tetraselmis chui, Phaeodactylum tricornutum, Spirulina sp., and Nannochloropsis oceanica). Screening for antioxidant activity was also performed to understand the relationship between FA profile and bioactivity. Microalgae exhibited specific FA profiles with a different composition, namely in the ω-3 FA profile, but with species of the same phylum showing similar tendencies. The different lipid extracts showed similar antioxidant activities, but with a low activity of the extracts of Nannochloropsis oceanica. Overall, this study provides a direct comparison of FA profiles between microalgae species, supporting the role of these species as alternative, sustainable, and healthy sources of essential lipids.

Nitrated phospholipids have recently been detected in vitro and in vivo and associated with beneficial health effects. They were identified and quantified in biological samples by lipidomics methodologies using liquid chromatography-collision-induced dissociation (CID) tandem mass spectrometry (MS/MS) acquired with the linear ion trap mass spectrometer. Only a few studies have used higher-energy collision dissociation (HCD)-MS/MS in high-resolution Orbitraps to characterize nitrated phosphatidylserines and nitrated cardiolipins, highlighting the marked differences in the fragmentation patterns when using CID or HCD fragmentation methods. In this study, we aimed to evaluate the fragmentation of nitrated phosphatidylcholine and nitrated phosphatidylethanolamine species under HCD-MS/MS. We studied the effect of normalized collision energy (NCE) in the fragmentation pattern to identify the best acquisition conditions and reporter ions to detect nitrated phospholipids. The results showed that the intensity of the typical neutral loss of nitrous acid (HNO₂) diminishes with increasing NCE, becoming non-detectable for a higher NCE. Thus, the loss of HNO₂ could not be the most suitable ion/fragment for the characterization of nitrated phospholipids under HCD. In HCD-MS/MS new fragment ions were identified, corresponding to the nitrated fatty acyl chains, NO₂-RCOO⁻, (NO₂-RCOOH-H₂O + H)⁺, and (NO₂-RCOOH + H)⁺, suggested as potential reporter ions to detect nitrated phospholipids when using the HCD-MS/MS lipidomics analysis.

Dunaliella salina is a green microalga extensively explored for β-carotene production, while knowledge of its lipid composition is still limited and poorly investigated. Among lipids, polar lipids have been highlighted as bioactive phytochemicals with health-promoting properties. This research aimed to provide an in-depth lipidome profiling of D. salina using liquid and gas chromatography coupled with mass spectrometry. The lipid content was 6.8%, including phospholipids, glycolipids, betaine lipids, sphingolipids, triglycerides, diglycerides, and pigments. Among the total esterified fatty acids, 13.6% were 18:3 omega-3 and 14.7% were 18:1 omega-9. The lipid extract of D. salina showed anti-inflammatory activity by inhibiting cyclooxygenase-2 activity at 100 µg/mL, dose-dependent antioxidant scavenging activity, and antidiabetic activity by inhibiting α-glucosidase activity at 25 and 125 µg/mL. In conclusion, the lipid extract of D. salina has the potential to be used as a functional food ingredient or in the nutraceutical and cosmeceutical industries.

Acute myocardial infarction (AMI) is the leading cause of death, morbidity, and health costs worldwide. In AMI, a sudden blockage of blood flow causes myocardial ischemia and cell death. Reperfusion after ischemia has paradoxical effects and may exacerbate the myocardial injury, a process known as ischemic reperfusion injury. In this work we evaluated the lipidome of isolated rat hearts, maintained in controlled perfusion (CT), undergoing global ischemia (ISC) or ischemia followed by reperfusion (IR). 153 polar lipid levels were significantly different between conditions. 48 features had q < 0.001 and included 8 phosphatidylcholines and 4 lysophospholipids, which were lower in ISC compared to CT, and even lower in the IR group, suggesting that IR induces more profound changes than ISC. We observed that the levels of 16 alkyl acyl phospholipids were significantly altered during ISC and IR. Overall, these data indicate that myocardial lipid remodelling and possibly damage occurs to a greater extent during reperfusion. The adaptation of cardiac lipidome during ISC and IR described is consistent with the presence of oxidative damage and may reflect the impact of AMI on the lipidome at the cellular level and provide new insights into the role of lipids in the pathophysiology of acute myocardial ischemia/reperfusion injury.

Nitrated lipids have been detected in vitro and in vivo, usually associated with a protective effect. While nitrated fatty acids have been widely studied, few studies reported the nitration and nitroxidation of the phospholipid classes phosphatidylcholine, and phosphatidylethanolamine. However, no information regarding nitrated and nitroxidized phosphatidylserine can be found in the literature. This work aims to identify and characterize the nitrated and nitroxidized derivatives of 1-palmitoyl-2-oleoyl-sn-3-glycero-phosphoserine (POPS), obtained after incubation with nitronium tetrafluoroborate, by liquid chromatography (LC) coupled to mass spectrometry (MS) and tandem MS (MS/MS). Several nitrated and nitroxidized products were identified, namely, nitro, nitroso, nitronitroso, and dinitro derivatives, as well as some nitroxidized species such as nitrosohydroxy, nitrohydroxy, and nitrohydroperoxy. The fragmentation pathways identified were structure-dependent and included the loss of HNO and HNO₂ for nitroso and nitro derivatives, respectively. Combined losses of PS polar head group plus HNO or HNO₂ and carboxylate anions of modified fatty acyl chain were also observed. The nitrated POPS also showed antiradical potential, demonstrated by the ability to scavenge the ABTS^●+ and DPPH^● radicals. Overall, this in vitro model of nitration based on LC-MS/MS provided additional insights into the nitrated and nitroxidized derivatives of PS and their fragmentation fingerprinting. This information is a valuable tool for targeted analysis of these modified PS in complex biological samples, to further explore the new clues on the antioxidant potential of nitrated POPS.