[GRAPHICS]The novel alkaloids 1 and 4 were isolated from an Australian non-verongid sponge, Oceanapia sp, Compound 1 contains an unprecedented imidazolyl-quinolinone substructure attached to a bromotyrosine-derived spiro isoxazoline. Three other known alkaloids were isolated in addition to 1 and 4 and together represent the first examples of inhibitors of a new mycobacterial enzyme mycothiol S-conjugate amidase (MCA).