Ethanol Extraction of Polar Lipids from Nannochloropsis oceanica for Food, Feed, and Biotechnology Applications Evaluated Using Lipidomic Approaches

Abstract

Nannochloropsis oceanica can accumulate lipids and is a good source of polar lipids, which are emerging as new value-added compounds with high commercial value for the food, nutraceutical, and pharmaceutical industries. Some applications may limit the extraction solvents, such as food applications that require safe food-grade solvents, such as ethanol. However, the effect of using ethanol as an extraction solvent on the quality of the extracted polar lipidome, compared to other more traditional methods, is not yet well established. In this study, the polar lipid profile of N. oceanica extracts was obtained using different solvents, including chloroform/methanol (CM), dichloromethane/methanol (DM), dichloromethane/ethanol (DE), and ethanol (E), and evaluated by modern lipidomic methods using LC-MS/MS. Ultrasonic bath (E + USB)- and ultrasonic probe (E + USP)-assisted methodologies were implemented to increase the lipid extraction yields using ethanol. The polar lipid signature and antioxidant activity of DM, E + USB, and E + USP resemble conventional CM, demonstrating a similar extraction efficiency, while the DE and ethanol extracts were significantly different. Our results showed the impact of different extraction solvents in the polar lipid composition of the final extracts and demonstrated the feasibility of E + USB and E + USP as safe and food-grade sources of polar lipids, with the potential for high-added-value biotechnological applications.

Effects of Structural and Compositional Changes of Nanochloropsis oceania after Enzyme Treatment on EPA-Rich Lipids Extraction

“…The lipid species identified here were consistent with those previously reported for Nannochloropsis [ 34 ]. Relative to the control, neutral lipid, glycolipid, and phospholipid levels were all lower after combined enzyme treatment ( Figure 2 ).…”

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

“…Lipidomics has also been applied to find alternative extraction procedures using food grade solvents and sustainable methodologies to obtain lipid extracts compatible with food applications. 8,91 In the case of N. oceanica and C. vulgaris the authors reported that lipid extracts obtained using ethanol and assisted with ultrasound had a lipid composition similar to those obtained using conventional methods based on Folch extraction protocol. 6,8,91 The authors of these studies suggested an alternative green lipid extraction method to provide safe extracts for functional food applications.…”

“…The replacement of chloroform by dichloromethane in the Bligh and Dyer method 5 or Folch method 6 was shown to give in most cases similar yields of lipid extraction and similar results in the lipidome profile as reported for the microalgae Nannochloropsis oceanica. 7,8 However, the use of different proportions of organic solvents or cell disruption methods can result in different yields of lipids. 9 Lipid extraction using MTBE:methanol is becoming popular in lipidomic analysis because the MTBE:methanol phase (the organic phase with the dissolved lipids) is in the upper phase, which makes handling much easier than with chloroform or dichloromethane.…”

“…Despite this trend, the same study suggests a species-specific polar lipidome, identifying only 35 species shared among the six macroalgae surveyed. 64 Studies on microalgae unveiled the lipidome of several species from Chlorophyta, [65][66][67][68] Ochrophyta, 8,67,[69][70][71][72][73][74][75] Cyanobacteria, 76 Haptophyta, 38,77,78 Bigyra 68 and Myzozoa 70 phyla (Table S1, ESI †). Most lipidomics studies in microalgae identify GL classes, such as DGDG, MGDG and SQDG; PL classes, including PG, PC, PE, PI; BL classes, including DGTS, DGCC and DGTA; and TG.…”

“…Some studies have evaluated the bioactivity of lipid extracts from macro and microalgae 89,90 without lipid characterization. On the other hand, total lipid extracts of algae have been evaluated using antioxidant, 8,58,59,61,63,65,66,91 anti-inflammatory, 24,59,88,[92][93][94][95][96] antiproliferative, 88 antitumor, 97 antiatherogenic, 99 anti-viral 98,100-102 assays followed by characterization of the bioactive extract by LC-MS or nuclear magnetic resonance (NMR). These studies identified molecular species of GL, PL, BL and galactosylceramides as bioactive compounds.…”