Lipid Composition, Content of Polyphenols, and Antiradical Activity in Some Representatives of Marine Algae

Qualitative and quantitative composition of the lipid complex and total content of polyphenols were compared in aqueous alcoholic extracts from three species of marine macrophytes collected in Peter the Great Bay, the Sea of Japan. Examined seaweeds belonged to different phyla: green alga Ulva lactuca L. sea lettuce, brown alga Sargassum pallidum (Turner) C. Agardh sargassum pallidum, and red alga Ahnfeltia tobuchiensis (Kanno et Matsubara) Makijenko ahnfeltia tobuchiensis. It was shown that glycolipids (30.3–41.5%) and neutral lipids (34–48.5%) prevailed among total lipids in the extracts from all three algal species; phospholipids accounted for 10–25.7% of total lipids. Among neutral lipids in all the seaweeds, triacylglycerols and free sterols prevailed. The greatest quantity of triacylglycerols was found in A.tobuchiensis and that of free sterols was in S. pallidum. As to the individual fractions of phospholipids, their composition and content considerably differed. In terms of content, predominant phospholipid fractions in the extract from U. lactuca were phosphatidyl glycerol, phosphatidyl ethanolamine, and phosphatidyl inositol, those from S. pallidum were phosphatidyl ethanolamine and phosphatidyl glycerol, and those from A. tobuchiensis were phosphatidyl choline and phosphatidyl glycerol. As to the percentage of main fatty acids comprising the lipid component of the extracts from the examined algal species, it was found that the extract from brown alga S. pallidum contained the greatest content of PUFA from the family n-6. The extract from green alga U. lactuca contained the greatest content of PUFA from the family n-3. In the extract from red alga A. tobuchiensis, arachidonic (family n-6) and eicosapentaenoic (family n-3) acids prevailed among PUFA. The greatest quantity of polyphenols was detected in the extract from brown alga S. pallidum, which 15–24 times exceeded respective figures in U. lactuca and A. tobuchiensis. Moreover, the extract from S. pallidum showed a much higher level of antiradical activity in respect to ABTS⁺, which was 5–12.5 times greater than in U. lactuca and A. tobuchiensis, respectively.