Cytotoxic Polyacetylenes from the Red Sea Sponge Siphonochalina siphonella

wo new polyacetylenes, callyspongenol-D (1) and callyspongendiol (2), the known 
polyacetylene dehydrosiphonochalynol (3), and the known triterpenoid sipholenol-A (4) 
were isolated from the Red Sea sponge Siphonochalina siphonella. Their chemical 
structures were elucidated on the basis of spectroscopic analyses. The cytotoxicity of the 
isolated compounds towards the human mammary carcinoma cell line MCF-7 was 
determined by the lactate dehydrogenase (LDH) assay, and compounds 4 and 1 were ...