Novel Cytotoxic Polyoxygenated Steroids from an Okinawan Sponge Dysidea sp.

Abstract

A library of extracts established from hundreds of marine organisms was screened by a cytotoxicity test. The active organic extract of an Okinawan marine sponge of the genus Dysidea was subjected to bioassay-guided fractionation to give three new polyoxygenated steroids dysideasterols F-H (1–3), together with two known related compounds (4 and 5). Their structures were confirmed by NMR and mass spectroscopic analyses. A characteristic structural feature of 2, 4 and 5 is an allylic epoxide, whereas this epoxide undergoes ring-opening by a neighbouring hydroxyl group to give a tetrahydrofuran ring in 1 and 3. All compounds 1–5 exhibited a similar cytotoxic effect with IC₅₀ values of 0.15–0.3 µM against human epidermoid carcinoma A431 cells, demonstrating that the allylic epoxide moiety was not responsible for this cytotoxic effect.

• cytotoxicity
• sponge
• Dysidea
• marine natural product
• steroid