Penochalasins, a novel class of cytotoxic cytochalasans from a Penicillium species separated from a marine alga: structure determination and solution conformation

A novel class of cytochalasans, penochalasins A 1, B and C, have been isolated from a strain of Penicillium sp. originally separated from the marine alga Enteromorpha intestinalis, and their stereostructures have been established on the basis of NMR spectral analyses and chemical transformations. Different conformations of 1 in CDCl3 and [2H5]pyridine were determined by analysis of NMR data and molecular modelling. All the compounds exhibited potent cytotoxicity against cultured P388 cells.