Two novel polyoxygenated steroids, incrustasterol A (1) and B (2), hav
e been isolated from the marine sponge Dysidea incrustans, collected i
n the Mediterranean sea along the coasts of Tunisia. The structures, w
hich include a rare Delta(8(9)), 11-keto functionality along with othe
r oxygenated functions on the rings A and B, were determined by interp
retation of spectral data. These steroids were cytotoxic against human
non-small-cell lung, renal and melanoma carcinoma cell lines.