Coelenterates, sterols

Coelenterates and Echinoderms. Coelenterate and echinoderm toxins range from small molecular weight amines, to sterols, to large complex carbohydrate chains, to proteins of over 100,000 daltons. Molecular size sometimes reflects taxonomy, e.g., sea anemones (Actiniaria) all possess toxic polypeptides varying in size from 3,000 to 10,000 daltons while jellyfish contain toxic proteins (ca. 100,000 daltons). Carotenoids have been isolated from Asterias species (starfish), Echinoidea (sea urchins), and Anthozoans such as Actiniaria (sea anemones) and the corals. These are sometimes complexed with sterols (J5). 

Goad (40) and others have extensively reviewed coelenterate and echinoderm sterols including the saponins found in starfish and sea cucumbers. Cholesterol is a common sterol in most families, except for gorgonians and zoanthids some soft corals contain polyhydroxylated sterols. The amount of variation associated with phylogeny is illustrate in the echinoderms by the fact that crinoids, ophuiroids, and echinoids contain A 5 sterols while holothuriodeans and asteroids contain A 7 sterols. Some classes contain uniquely structured sterols. 

Complex mixtures of mostly A -sterols, with cholesterol usually dominant, are found in the Coelenterates (1). Some species are of interest b use they possess the unusual C30 sterol gorgosterol. At present there is very little evidence to support biosynthesis of sterols in Coelenterates. 

Ciereszko, L.S., Johnson, M.A., Schmidt, R.W., and Koons, C.B. (1968) Chemistry of coelenterates-VI. Occurrence of gorgosterol, a C30 sterol, in coelenterates and their zooxanthellae. Comp. Biochem. Physiol, 24, 899-904. 

It is worth pointing out that this is the first occurrence in sponges of sterols with twenty-six carbon atoms (24-nor) they are widespread in marine invertebrates and to date have been reported in four marine phyla, the Coelenterates 181), the Echinoderms (99), the Molluscs 120), and the Tunicates 180). 

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