NOVEL MARINE POLYHYDROXYLATED STEROIDS FROM THE STARFISH MYXODERMA-PLATYACANTHUM

Nine polyhydroxy steroids and two steroid glycosides have been isolated from the starfish Myxoderma platyacanthum. The novel compounds 1-7 possess the same 3-beta, 5-alpha,6-beta,15-alpha-tetrol necleus (15-sulfated in 1 and 3) but differ in the side chains. Two levels of oxidation (CH2OH and CO2H) at the side chain methyls were encountered in this class of steroids; in 6 and 7 the 26-carboxylic acid function is found as amide derivative of taurine. The novel compound 8 is an asterosaponin assigned as myxodermoside A, consisting of a DELTA-9(11) 3-beta,6-alpha-dihydroxysteroidal moiety, a tetrasaccharide portion attached at C-6, and a sulfate group at C-3. Steroids 9-11 have known structures. The general structure of the novel compounds was determined from spectral data (H-1 and C-13 NMR and FAB MS), and the stereochemistry of the side chains was determined by correlating the respective spectral data with those of synthetic models of known configuration. The stereoselective synthesis of the steroid 4 side chain (DELTA-22E, 27-nor-24-methyl-26-carboxy) is also described.