Phylum echinodermata holothuroidea

Further work in the phylum Echinodermata shows a variable ability to biosynthesize steroids. In the class Holothuroidea and Echinoidea, the representatives examined could synthesize squalene but not triterpenoids or sterols from acetate. However, several examples from the class Asteroidea were able to synthesize squalene, lanosterol, and other steroids. In the later stages of steroid metabolism it was shown that cholesterol was converted into cholest-7-enol via cholestanol. 

In addition to Asteroidea and Holothuroidea, the phylum Echinodermata (Greek echinos, spiny derma, skin) comprises the classes Ophiuroidea (brittle stars), Crinoidea (sea lilies and feather stars) and Echinoidea (sea urchins). There is no report of occurrence of steroid or triterpenoid glycosides in sea lilies, feather stars or sea urchins. Brittle stars contain sulfated polyhydroxylated steroids [10-12] and only two sulfated steroidal monoglycosides have been isolated from the brittle star Ophioderma longicaudum [13]. 

Sea cucumbers belong to the phylum Echinodermata, class Holothuroidea, and are thus also called holothuroids. Of the approximately 1400 species that have been described so far, some 77 are harvested commercially at various scales around the world (Purcell et al, in press). While the footballshaped shmy creatures are not necessarily attractive at first glance, they are nonetheless a prized commodity. 

The chemotaxonomic relations observed in the phylum Echinodermata are particularly clear each class is characterized by a particular set of secondary metabolites that is probably specific to the class. For the class Crinoidea, these are anthraquinonic pigments, often sulfated, which have been found in all species studied. The other four classes of echinoderms also contain quinonic pigments but these are naphthoquinones, which are widespread among Echinoidea (spinochromes), rare in Asteroidea and Ophiuroidea, and exceptional among Holothuroidea (Scheuer, 1973). 

---