A new compound,8,8′-dienecyclostellettamine,was isolated from the marine sponge Amphimedon compressa.Its structure was elucidated by spectroscopic methods including ID and 2D NMR,UV,IR,ESI-MS,MALDI-MS techniques.It is probably an important precursor of the manzamine alkoids,and also showed vigorous antibacterial activities. A new compound, 8,8’-dienecyclostellettamine, was isolated from the marine sponge Amphimedon compressa. Its structure was elucidated by spectroscopic methods including ID and 2D NMR, UV, IR, ESI-MS, MALDI-MS techniques. It is probably an important precursor of the manzamine alkoids, and also showed vigorous antibacterial activities.