A new sesterterpene, 12-deacetoxyscalaradial [2a] has been isolated fr
om the sponge Cacospongia mollior, together with the previously descri
bed scalaradial [2b] and furoscalarol [3]. The structure of the new co
mpound, proposed by spectral data, was confirmed by X-ray diffraction
analysis. Compound 2a is the first scalarane sesterterpenoid, without
a substituent at C-12, to have been identified in nature. It shows hig
h antifeedant activity and is hot to taste for the human tongue. Both
2a and 2b display cytotoxic activity.