Cytotoxic cytochalasins from the endozoic fungus Phoma sp. of the giant jellyfish Nemopilema nomurai

Four new cytochalasin derivatives (1-4), together with cytochalasin B (5), were isolated from the fungus Phoma sp. obtained from the giant jellyfish Nemopilema nomurai. The planar structure and relative stereochemistry were established by analysis of 1D and 2D NMR data. The absolute configuration was defined by the modified Mosher's method. The compounds showed significant cytotoxicity against a small panel of human solid tumor cell lines (A549, SK-OV-3, SK-MEL-2, XF 498, and HCT15) with IC50 values in the range of 0.5-30 μM. The cytochalasin B (5) showed obvious cytotoxicity with IC50 of 7.9 μM against HeLa human cervical carcinoma cells.