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 glycolipi ds, monogalactosyldiacylglycerol, digalactosyldiacylglycerol and sulph oquinovosyldiacylglycerol, and the phospholipids phosphatidylglycerol and phosphatidylethanolamine (the latter with exceptions) were present in all the species examined. The occurrence of phosphatidylcholine an d of the betaine lipid, diacylglycerylhydroxymethyltrimethyl-beta-alan ine (DGTA) partly reflects the brown algal taxonomy. Based on a detect ion limit of 0.5 mug per mg of total lipid, DGTA is present in the ord ers Tilopteridales, Dictyotales, Notheiales, Fucales, Durvillaeales an d, with one exception, in the Sphacelariales. It is absent, however, f rom Sporochnales, Desmarestiales, Dictyosiphonales, Laminariales, Asco seirales, Syringodermatales, and with one exception each, in Cutlerial es and Scytosiphonales. Ectocarpales and Chordariales are mixed groups with DGTA-positive and DGTA-negative species. Phosphatidylcholine cou ld not be detected in the orders Dictyotales, Durvillaeales and, with a few exceptions, the Fucales. Diacylglyceryltrimethylhomoserine is li kely to occur in trace amounts in several species of brown algae.