Dermasterias imbricata

The absolute stereochemistries for both compounds were determined by CD analysis of the p-bromobenzoate derivatives. Two other eicosanoids were also isolated from whole animals [198], The trihydroxylated oxylipin 8jR,11S,12R-trihydroxyeicosa-5Z,9 ,14Z,17Z-tetraenoic acid (trioxilin A4,150) was detected in, or isolated from, five starfish species P. miniata, Dermasterias imbricata, Pycnopodia helianthoides, Culcita novaeguinea, and Nardoa tubercolata. Its structure was determined by H and 13C NMR and FAB-MS analyses of the natural product and of an acetonide derivative. The co6 analog of this compound (151) was isolated only from P. helianthoides. The relative stereochemistry in these metabolites (150, 151) was established from a comparison of NMR shifts with malyngic acid, a trihydroxylated C18 compound isolated from Lyngbya majuscula, while the absolute stereochemistry was proposed on the basis of the earlier isolation of 8R-HETE from P. miniata. 

Many starfish cause an escape response in usually sessile marine invertebrates [7]. The starfish Dermasterias imbricata causes the sea anemone Stomphia coccinea to release its basal disc from the substratum and swim away on contact. Bioassay-directed fractionation of the starfish extract led to the isolation of the compound found to elicit this response, the benzyltetrahydroisoquinoline alkaloid imbricatine (646). The structure of compound 646 was elucidated by spectral data interpretation. The amino acid residue in imbricatine is related to the thiol containing amino acids ovothiols A-C. Imbricatine (646) is active in both LI210 and P388... 

Pathirana, C. and Andersen, R. J., Imbricatine, an unusual benzyltetrahydroisoquinoline alkaloid isolated from the starfish Dermasterias imbricata, J. Am. Chem. Soc., 108, 8288, 1986. 

I. Bruno, L. Minale, and R. Riccio, Starfish saponins, part 43. Structures of two new sulfated steroidal fucofuranosides (imbricatosides A and B) and six new polyhydroxysteroids from starfish Dermasterias imbricata, J. Nat. Prod., 53 (1990) 366-374. 

Imbricatine. C24H26N4O7S, Mr 514.55, a benzyl(tet-rahydro)isoquinoline and imidazole alkaloid from the starfish Dermasterias imbricata. I. is as yet the only alkaloid of this class that does not originate from a plant source. I. induces an escape reaction in the sea anemone Stomphia coccinea when it comes into contact with the starfish. I. has cytotoxic activity against leukemia cell lines. 

Deoxy-2,4-di-0-methyl-p-D-glucopyranosyl- l- 2)-6-deoxy-5-O-sulfo-p-D-galactofuranoside] [128855-06-1]. Imbricatoside A C41H62O18S M 874.996 Constit. of Dermasterias imbricata. 

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