Abstract: Bastadins-6,-9 and-16 isolated from the marine sponge Ianthella basta displayed in vitro cytostatic and/or cytotoxic effects in six human and mouse cancer cell lines. The in vitro growth inhibitory effects of these bastadins were similar in cancer cell lines sensitive to pro-apoptotic stimuli versus cancer cell lines displaying various levels of resistance to pro- apoptotic stimuli. While about ten times less toxic than the natural cyclic bastadins, the ...