DOWNEYOSIDE-A AND DOWNEYOSIDE-B, 2 NEW SULFATED STEROID GLUCURONIDES FROM THE STARFISH HENRICIA-DOWNEYAE

Two new sulphated polyhydroxylated steroid glucuronides, downeyoside A and B (1, 2), C-24 methyl epimers possessing an ethereal ring Linking C-16 to C-22 of the steroid, were isolated from the starfish Henricia downeyae collected from the Gulf of Mexico. Their structures were det ermined by spectral analysis and the stereochemistry of the highly oxy genated steroid side chain was derived from NMR data combined with mol ecular dynamics calculation. Compounds 1 and 2 were tested against non -small-cell lung human carcinoma cells and found to be cytotoxic with IC50 of 60 mu g/ml and 36 mu g/ml, respectively.