Occurrence of steryl glycosides and acylated steryl glycosides in some marine algae

There is some controversy concerning the presence of steryl glycosides and acylated steryl glycosides in eucaryotic algae. These two classes of sterol compounds were investigated in species belonging to the three major groups of eucaryotic algae: green algae (Ulva gigantea, Cladophora rupestris), brown algae (Fucus vesiculosus, Ascophyllum nodosum), and red algae (Rhodymenia palmata, Porphyridium sp.). All these algae contain both steryl glycosides and acylated steryl glycosides. The sterol components of these compounds vary according to the alga but they are always the same as the free sterols of the alga in question. The most common sugar moiety is glucose. In the acylated steryl glycosides, the fatty acid is mainly palmitic acid. The percentage of these compounds (as a percentage of the total sterol content) is often low.