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Keywords:

  • algal lipid;
  • arachidonic acid;
  • chemoecology;
  • eicosapentaenoic acid;
  • lipid biomarker;
  • marine grazing food chain;
  • polyunsaturated fatty acids

The lipid and fatty acid compositions in two edible subtropical algae (the brown alga Cladosiphon okamuranus Tokida and the green alga Caulerpa lentillifera J. Agardh) were determined to clarify their lipid characteristics and nutritional values. Glycolipids and phospholipids were the major lipid classes, with significant levels of triacylglycerols. Polyunsaturated fatty acids (PUFA) were the major fatty acids of both algae. The lipid class composition and major fatty acids were similar in both the algal species, irrespective of wild and cultured specimens. Typical n-6 PUFA, such as 18:2n-6 (linoleic acid) and 20:4n-6 (arachidonic acid), occurred in characteristically high levels in both of the algae. High levels of n-3 PUFA were measured in all lipid classes of both species without 22:6n-3 (docosahexaenoic acid), 18:3n-3, 18:4n-3, and 20:5n-3 (eicosapentaenoic acid) for Cl. okamuranus; and 16:3n-3, 18:3n-3, and 20:5n-3 for Ca. lentillifera. The finding suggests that the green algal species, which mainly biosynthesizes short-chain (C16 and C18) PUFA, differs from that of the brown alga, which is capable of biosynthesizing high 20:5n-3 levels. The PUFA levels in glycolipids of the two algal species comprised up to 60%, even though they are subtropical marine species. High n-6 PUFA levels in the algal lipids probably influence the significant levels of n-6 PUFA in herbivorous fishes, because the n-6 PUFA levels in marine fish lipids are generally undetectable or negligible.