To expand our knowledge of lipid and fatty acid (FA) biosynthesis in marine cnidarians, polar lipidomes of hydrocorals were studied for the first time and then compared with those of soft corals from tropical and boreal regions. The structure and content of FAs and molecular species of ethanolamine, choline, serine, and inositol glycerophospholipids (PE, PC, PS, and PI, respectively), and ceramide aminoethylphosphonate (CAEP) in tropical hydrocorals ( Millepora platyphylla , M . dichotoma ) and the cold-water hydrocoral Allopora steinegeri were determined by chromatography and mass spectrometry. All soft corals and cold-water hydrocorals are characterized by a considerable amount of C 20 polyunsaturated FAs (PUFAs) elongated into C 22 PUFAs. In the Millepora species, the high level of 22:5n-6 and 22:6n-3 against the background of the extremely low level of C 20 PUFAs may be explained by a high activity of rare Δ4 desaturase. In contrast to hydrocorals, soft corals are able to elongate and further desaturate C 22 PUFAs into C 24 PUFAs. Allopora and soft corals use C 20 PUFAs mainly for the synthesis of PE and PC. The molecular species of PS of soft corals concentrate C 24 PUFAs, while in Allopora and Millepora the PS molecules are mainly based on 22:4n-6 and 22:5n-6 acyl groups, respectively. Short acyl groups (C 14 ) dominate the CAEP molecules of Allopora . In all the animals compared, most molecular species of PE and PC are ether lipids, but diacyl molecular species dominate PI. Hydrocorals and tropical soft corals contain diacyl and ether PS molecules, respectively, whereas cold-water soft corals contain a mixture of these PS forms. The high similarity of the alkyl/acyl compositions indicates a possible biosynthetic relationship between PS and PI in hydrocorals. The data obtained in our study will provide a resource to further investigate the lipid metabolism in marine invertebrates.

The soft corals of the genus Xenia are common for Indo-Pacific reef ecosystems. Lipid class, fatty acid (FA), phospho- and phosphonolipid molecular species compositions were identified for the first time in the soft coral Xenia sp. from Vietnam. Total lipids consisted predominantly of waxes, monoalkyl diacylglycerols, triacylglycerols, sterols, and polar lipids (21.4, 7.7, 14.2, 10.5, and 36.7 %, respectively). Sesquiterpene alcohol, valerenenol, was found. Acids 16:0, 18:3n-6, 20:4n-6, and 20:5n-3 dominated in total FA. The markers of zooxanthellae (18:4n-3 and 18:5n-3) and octocorals (24:5n-6 and 24:6n-3) were detected. Acids 18:5n-3, 20:4n-6, 22:4n-6, and 24:5n-6 concentrated in FA of polar lipids, whereas 14:0, 16:0, 16:1n-7, 18:2n-6, and 18:3n-6 were the major FA of neutral lipids. ChoGpl, EtnGpl, SerGpl, CAEP, PtdIns, and lyso ChoGpl constituted 39.5, 20.8, 20.5, 9.7, 4.3, and 5.3 %, respectively, of the sum of phospho- and phosphonolipids. Thirty-two molecular species of phospholipids and ceramide aminoethylphosphonate (CAEP) were determined by high resolution tandem mass spectrometry. Lyso 18:0e PakCho (4.1 %), 18:0e/20:4 PakCho (20.5 %), 18:1e/20:4 PlsEtn (18.0 %), 18:0e/24:5 PakSer (14.0 %), and 16:0 CAEP (9.6 %) were the major molecular species. EtnGpl and PtdIns mainly consisted of alkenyl acyl and diacyl forms, respectively. Alkyl acyl forms predominated in ChoGpl and SerGpl. Acid 24:5n-6 was a principal FA in SerGpl, whereas 20:4n-6 was more abundant in ChoGpl and EtnGpl. PtdIns contained various C20-24 PUFA. In the context of chemotaxonomy of corals, Xenia sp. has the lipid composition typical for soft corals and the FA profile similar to that of alcyonarians with the high level of 18:3n-6.

Fatty acids (FAs) of soft corals contain two very-long-chain tetracosapolyenoic acids (TPA, 24:5n-6 and 24:6n-3), which are chemotaxonomic markers of all species of the subclass Octocorallia. The distribution of TPA in molecular species of different phospholipid (PL) classes was investigated for the first time in the soft corals Sinularia macropodia and Capnella sp. From shallow waters of Vietnam. Phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylserine (PS), and phosphatidylinositol (PI) were the major PL classes of S. macropodia and Capnella sp. More than thirty two molecular species of these four PL classes were determined by high resolution tandem mass spectrometry.

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This study attempted the lipid extraction process from the seeds of Madhuca ellitica, a lipid-rich plant, and conducted a lipidomic analysis on molecular species of the obtained product. Total lipids of the crude seeds were found to contain 11.2% of polar lipids. The major fatty acids (FAs) of the polar lipids were palmitic (16:0), stearic (18:0), oleic (18:1n-9), and linoleic (18:2n-6) acids, which amounted to 28.5, 12.5, 44.8, and 13.2% of total FAs, respectively. The content and chemical structures of individual molecular species of phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidic acid (PA), and sulfoquinovosyldiacylglycerol (SQDG) were determined by HPLC with a tandem high-resolution mass spectrometry (HRMS). The major molecular species were 18:1/18:2 PE, 16:0/18:1 PC, 18:1/18:2 PC, 16:0/18:2 PG, 16:0/18:1 PG, 16:1/18:1 PI, 16:0/18:1 PI, 18:0/18:2 PI, 16:0/18:1 PA, 18:1/18:2 PA, 16:0/18:1 SQDG, and 18:0/18:1 SQDG. The application of a tandem HRMS allows us to determine the content of each isomer in pairs of the monoisotopic molecular species, for example, 18:0/18:2 and 18:1/18:1. The evaluation of the seed polar lipid profile will be helpful for developing the potential of this tree for nutritive and industrial uses.