Dictazolines A and B, bisspiroimidazolidinones from the marine sponge Smenospongia cerebriformis

An extensive study of the secondary metabolites produced by the marine sponge Smenospongia crebriformis has led to the isolation of two new bisspiroimidazolidinone derivatives, dictazolines A (1) and B (2), along with the known soft coral metabolites tubastrindoles A (3) and B (4). The structures were assigned by 2D NMR spectroscopic methods.