Stellettazole A: An antibacterial guanidinoimidazole alkaloid from a marine sponge Stelletta sp.☆

Abstract A new guanidinoimidazole alkaloid, stellettazole A ( 1 ), has been isolated from a marine sponge Stelletta sp. as an antibacterial constituent. Its structure was determined on the basis of spectral data and chemical degradation. Stellettazole A also inhibited Ca + /calmodulin-dependent phosphodiesterase.