New bioactive pregnadiene-derived glycosides from the Gulf of California gorgonian Muricea cf. austera

Two new steroidal glycosides, pregna-5,20-diene-3-O-beta-glucopyranoside (1), and pregna-5,20-diene-3-O-beta-(6'-O-acetyl) glucopyranoside (2), and the known trihydroxy sterol, pregna-5-ene-3beta,20alpha,21-triol (3) have been isolated from the Gulf of California gorgonian Muricea cf, austera. The structures of the new compounds were established on the basis of chemical and spectral studies. Compound 2, and its peracetylated derivative, 4, displayed moderate in vitro cytotoxicity (IC50 = 17.3 and 14.3 mug/mL) toward HCT-116 human colon carcinoma. Compound 3 showed growth inhibition of Staphylococcus aureus and Bacillus subtilis at 250 mug/disk, in the agar disk-diffusion assay.