Structures of new amphidinols with truncated polyhydroxyl chain and their membrane-permeabilizing activities

Two new homologues of amphidinols (AM14 and AM15) were isolated from the cultured dinoflagellate Amphidinium klebsii. The structures were elucidated on the basis of 2D NMR and collision-induced dissociation MS/MS and turned out to be closely related homologues of AM7. Their weak membrane-disrupting activity indicates that the hydrophobic polyene chain is essential for the potent biological activities. Structure-activity relationship for the polyhydroxyl part was then examined with use of AM homologues possessing various chain lengths, indicating that the pore size of the channel/lesion formed by AMs was not greatly affected by the length of the polyhydroxyl chain.