Cytochalasin P1, a new cytochalasin from the marine-derived fungus Xylaria sp. SOF11.

A new cytochalasin, named cytochalasin P-1 (1), together with four known analogs (2-5) was isolated from marine-derived fungus Xylaria sp. SOF11 from the South China Sea. The structure of the new compound was elucidated on the basis of MS and NMR (H-1, C-13, HSQC, HMBC, and NOESY) data analyses. Compounds 1-5 were tested for their cytotoxicities against four tumor cell lines (SF-268, MCF-7, NCI-H460, and HepG-2). Compounds 1-5 showed significant cytotoxicity against two tumor cell lines MCF-7 and SF-268, with the IC50 values varying between 0.33 and 4.17 mu M.