Holothuroidea

Holothuroidea Kolga, Peniagone, Paroriza, Laetmogone, Paelopatides, etc. 

Sea cucumbers (Holothuroidea, Echinodermata) appear to be unique in their mode of squalene oxide (37) cyclization. Tritium-labeled lanosterol (33), cycloartenol (32) and parkeol (38) were individually administered to the sea cucumber Holothuria arenicola. While the former two triterpenes were not metabolized [22], parkeol was efficiently transformed into 14x-methyl-5a-cho-lest-9(l l)-en-3/ -ol (39) (Scheme 3). Other A1 sterols present in H. arenicola were not found to be radioactive and were thus assumed to be of dietary origin. The intermediacy of parkeol was confirmed by the feeding of labeled mevalonate (23) and squalene (26) to the sea cucumber Stichopus californicus [15]. Both precursors were transformed into parkeol, but not lanosterol nor cycloartenol, aqd to 4,14a-dimethyl-5a-cholest-9(ll)-en-3/J-ol (40) and 14a-methyl-5a-cholest-9(ll)-en-3/ -ol. Thus, while all other eukaryotes produce either cycloartenol or lanosterol, parkeol is the intermediate between triterpenes and the 14-methyl sterols in sea cucumbers. 

Korotchenko and coworkers detected PGs by TLC and bioassay in three sea cucumbers (Holothuroidea) Stichopus japonicus, Cucumaria fraudatrix, and C. japonica [189]. 

Echinoldea Asteroldea Holothuroidea Fish (otoliths) Leodia sexiesperforata Various spedes isostichopus badionothus Caiamus bajonado ... 

BIOLOGICALLY ACTIVE TRITERPENE GLYCOSIDES FROM SEA CUCUMBERS (HOLOTHUROIDEA, ECHINODERMATA)... 

The subphylum Eleutherozoa contains five classes. Class Concentricycloidea, containing only the genus Xyloplax, has no reported chemistry. Classes Asteroidea, Ophiuroidea, and Holothuroidea follow the pattern of the phylum as a whole, producing 222 (74%), 24 (100%), and 66 (94%) isoprenoid compounds, respectively. The majority of these isoprene compounds are sterols, many of which are cholestane, ergostadiene, or holostadiene derivatives. 

The compounds most characteristic of the phylum are the saponins, glycosolated sterols, most of which are sulfated. The suite of secondary metabolites produced by the classes Asteroidea, Ophiuroidea, and Holothuroidea are dominated by these sterols. It is believed that echinoderms do not generally undertake de novo synthesis of these sterols, but create them by modifying precursors obtained through feeding.90... 

Miller, R.L., Demonstration of sperm chemotaxis in Echinodermata Asteroidea, Holothuroidea, Ophiuroidea, J. Exp. Zool., 234, 283, 1985. 

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]. 

Several holothurins are specific for different taxonomic groups of sea cucumbers and structural characteristics of triterpene glycosides have been used to resolve taxonomic problems in the class Holothuroidea [57, 58]. For example, the triterpenoid glycosides distribution has been successfully applied in the reclassification of Stichopus mollis into the genus Australostichopus [59] and in the taxonomy of sea cucumbers belonging to the genus Cucumaria [60]. 

The chemistry of echinoderms, particularly the Holothuroidea (sea cucumbers) is characterized by the presence of saponins (triterpene glycosides) and sterol sulfates. Saponins are released by the sea cucumber s Cuvier gland when the organism is threatened. A number of biosynthetic investigations have addressed the origins of saponins and have yielded conflicting results. 

Bioactive Natural Products, Part I, ed. Atta-ur-Rahman, in Studies in Natural Products Chemistry, Vol. 28, Elsevier Science B.V., 2003 R 136 A. Braca, A.R. Bilia, J. Mendez, C. Pizza, I. Morelli and N. De Tommasi, Chemical and Biological Studies on Licania Genus , p. 35 R 137 H.D. Chludil, A.P. Murray, A.M. Seldes and M.S. Maier, Biologically Active Triterpene Glycosides from Sea Cucumbers (Holothuroidea, Echinodermata) , p. 587... 

Chao, S.M., Chen, C.P., and Alexander, P.S. (1995) Reproductive cycles of tropical sea cucumbers (Echinoder-mata Holothuroidea) in southern Taiwan. Marine Biology, 122, 289-295. 

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. 

EECKHAUTI (2004) The skin ulceration disease in cultivated juveniles of Holothu-ria scabra (Holothuroidea, Echinodermata). Aquaculture, 242,13-30. 

HAMEL J-F and MERCIER A (1996) Early development, settlement, growth, and spatial distribution of the sea cucumber Cucumaria frondosa (Echinodermata Holothuroidea). Canadian Journal of Fisheries and Aquatic Sciences, 53,253—271. 

HAMEL J-F, CONAND c, PAWSON D L and MERCIER A (2001) The sea cucumber Holothuria scabra (Holothuroidea Echinodermata) its biology and exploitation as beche-de-mer. Advances in Marine Biology, 41,129-223. 

MORGAN A D (1999) Husbandry and spawning of the sea cucumber Holothuria scabra (Echinodermata Holothuroidea), MSc thesis. University of Queensland. 

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