Isolation of 20 glycosides from the starfish Henricia downeyae, collected in the Gulf of Mexico.

Thirteen new (1-13) and seven known (14-20) steroid glycosides were isolated from Henricia downeyae, collected from the offshore waters of the northern Gulf of Mexico. Ethanolic extracts of these starfish caused growth inhibition in bacteria and fungi, potent antifouling activity against barnacle and bryozoan larvae, and feeding deterrent activity against a marine fish. The known compounds are typical glycosides found in several species of the family Echinasteridae, i.e., Echinaster sp. and Henricia laeviuscola. One of the new compounds belongs to this group, whereas the remaining 12 new compounds represent a novel series of steroid glycosides which have aglycons with structural similarities to the "asterosaponins". They possess a delta 9(11) 3 beta, 6 alpha-dihydroxysteroidal aglycon with 23-oxo or 22,23-epoxy functionalities and often a 20-hydroxyl group in the side chain. The sulfate is located at C-6 and the saccharide moiety at C-3, in contrast with the asterosaponins which have the sulfate at C-3 and the oligosaccaride moiety at C-6. All the new compounds contain a glucuronic acid unit, which is uncommon among steroid glycosides from echinoderms. The structures of the new compounds, isolated in amounts ranging from 3.4 to 0.9 mg, were determined by interpretation of their spectral data and by comparison with spectral data of known compounds.

Chemical and biological investigation of the polar constituents of the starfish Luidia clathrata, collected in the Gulf of Mexico.

Ten new [1-10] and three known [11-13] polyhydroxysteroids were isolated, along with four known asterosaponins [14-17], from the starfish Luidia clathrata, collected from the offshore waters of the northern Gulf of Mexico. The EtOH extracts of this starfish showed feeding-deterrent properties against marine fish, and inhibited the settlement of larvae of barnacles and bryozoans, as well as the growth of several bacteria. The structures of the new compounds were determined by interpretation of their nmr spectral data and by comparison with the spectral data of known compounds. The assignment of the configurations of the side-chain stereogenic centers of compounds 1 and 3-10 were based on the comparison of their nmr data with those of the stereoisomeric model compounds after derivatization with the chiral auxiliary MTPA reagent. Larval settlement assays conducted on ten isolated compounds revealed they are all potent inhibitors of settlement. Two of these isolated compounds inhibited the growth of several bacteria.

Starfish saponins, Part 2. Steroidal oligoglycosides from the starfish Cosmasterias lurida.

Four new sulfated asterosaponins, designated as cosmasterosides A [1], B [2], C [4], and D [5], have been isolated from the Atlantic starfish Cosmasterias lurida along with large amounts of the pentaglycoside ophidianoside F [3] and the minor component forbeside H [6], previously isolated from Ophidiaster ophidianus and Asterias forbesi, respectively. Cosmasteroside A [1] contains the same oligosaccharide chain as ophidianoside F [3] and a (20S)-5 alpha-cholesta-9(11),24-diene-3 beta,6 alpha,20-triol-3 beta-sulfated aglycone. Cosmasterosides B [2], C [4], and D [5] are based on the known aglycone, thornasterol A, and differ in the number and type of monosaccharide components of the carbohydrate chain. Cosmasteroside B [2] contains a novel oligosaccharide chain that differs from that of ophidianoside F [3] by the replacement of the quinovose unit attached to C-6 of the steroidal aglycone by glucose. The tetraglycosides cosmasterosides C [4] and D [5] are structurally related to ophidianoside F [3] and cosmasteroside B [2], respectively, by the loss of a terminal fucose unit.

Starfish saponins, 52. Chemical constituents from the starfish Echinaster brasiliensis.

This paper reports an analysis of the chemical constituents from the Caribbean starfish Echinaster brasiliensis collected at Grand Bahama Island. This species is completely devoid of cyclic steroidal glycosides, previously isolated from two species of the genus Echinaster in place of the more common penta- and hexa-glycoside steroidal sulfates ("asterosaponins"). Two typical "asterosaponins" and ten glycosides of polyhydroxysteroids were instead isolated in relatively large amounts from E. brasiliensis. The asterosaponins include the known marthasteroside A1 [1] and the new brasiliensoside [2], while the glycosides of polyhydroxysteroids include seven new compounds (six monoglycosides and one diglycoside). The known echinasteroside A, previously found in Echinaster sepositus and in the related Henricia laeviuscula (both belonging to the family Echinasteridae), and laeviusculosides C and I from H. laeviuscula were also isolated. Most of the glycosides from E. brasiliensis are 3-O-beta-xylopyranosides of delta 4-3 beta,6 beta,8,15 alpha,16 beta pentahydroxysteroid aglycones, having different side chains and sometimes a sulfate group at C-15, structural features which are typical of steroidal glycosides from starfishes of the family Echinasteridae. Continuing the analysis of the constituents of E. brasiliensis, we have also isolated a series of anthraquinones, known animal pigments found only in echinoderms and particularly in Crinoidea and in the Echinasteridae family of Asteroidea.