OPHIDIACEREBROSIDES - CYTOTOXIC GLYCOSPHINGOLIPIDS CONTAINING A NOVEL SPHINGOSINE FROM A SEA STAR

Five newly identified glycosphingolipids, ophidiacerebrosides, have been isolated from the sea star Ophidiaster ophidiamus. All five compounds showed strong cytotoxicity against L1210 leukemia cells in vitro. On the basis of chemical evidence and H-1 and C-13 NMR and mass spectre, the structure of ophidiacerebroside C, the major component, is assigned as (2S,3R,4E,8E,10E)-1-(beta-D-glucopyranosyloxy)-3-hydroxy-2- [((R)-2-hydroxydocosanoyl)amino]-9-methyl-4,8, 10-octadecatriene. This compound differs from previously isolated marine cerebrosides in that the sphingosine base contains a methyl branch and a conjugated diene. The other four ophidiacerebrosides, A, B, D, and E, were found from their FAB and H-1 NMR spectra and hydrolysis products to be identical to C with respect to the sphingosine and hexose units. However, the alpha-hydroxy fatty acids for the minor components differed in chain length.