Haterumaimides F-I, four new cytotoxic diterpene alkaloids from an ascidian Lissoclinum species.

Four new monochlorinated diterpene alkaloids, haterumaimides F-I (1-4), and two known ones, dichlorolissoclimide and chlorolissoclimide, were isolated from an ascidian Lissoclinum sp. Their structures with absolute stereochemistries were elucidated by chemical and spectral analyses. Haterumaimides F-I (1-4) inhibited the first cleavage of fertilized sea urchin eggs and exhibited potent to weak cytotoxicities against P388 cells.