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 is olated from Henricia downeyae, collected from the offshore waters of t he northern Gulf of Mexico. Ethanolic extracts of these starfish cause d 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 foun d in several species of the family Echinasteridae, i.e., Echinaster sp . and Henricia Laeviuscola. One of the new compounds belongs to this g roup, 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 locat ed at C-6 and the saccharide moiety at C-3, in contrast with the aster osaponins 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, we re determined by interpretation of their spectral data and by comparis on with spectral data of known compounds.