BETAINE LIPIDS AND PHOSPHOLIPIDS IN BROWN-ALGAE

The lipids of more than 100 species representing all of the 16 orders of brown algae (Phaeophyceae) have been analysed by TLC. The glycolipids, monogalactosyldiacylglycerol, digalactosyldiacylglycerol and sulphoquinovosyldiacylglycerol, and the phospholipids phosphatidylglycerol and phosphatidylethanolamine (the latter with exceptions) were present in all the species examined. The occurrence of phosphatidylcholine and of the betaine lipid, diacylglycerylhydroxymethyltrimethyl-beta-alanine (DGTA) partly reflects the brown algal taxonomy. Based on a detection limit of 0.5 mug per mg of total lipid, DGTA is present in the orders Tilopteridales, Dictyotales, Notheiales, Fucales, Durvillaeales and, with one exception, in the Sphacelariales. It is absent, however, from Sporochnales, Desmarestiales, Dictyosiphonales, Laminariales, Ascoseirales, Syringodermatales, and with one exception each, in Cutleriales and Scytosiphonales. Ectocarpales and Chordariales are mixed groups with DGTA-positive and DGTA-negative species. Phosphatidylcholine could not be detected in the orders Dictyotales, Durvillaeales and, with a few exceptions, the Fucales. Diacylglyceryltrimethylhomoserine is likely to occur in trace amounts in several species of brown algae.