Brominated tyrosine-derived metabolites from the sponge <i>Ianthella basta</i>

Seven novel metabolites, each originating from four bromotyrosine units, have been isolated from the sponge Ianthella basta . Bastadin-1 (2), bastadin-2(3) and bastadin-3(4) are derived from a single phenol oxidative coupling whilst the macrocyclic compounds bastadin-4(5), bastadin-5(6), bastadin-6(8) and bastadin-7(7) are formed by two phenol oxidative coupling reactions. Compounds (2)-(8) showed potent in vitro antimicrobial activity against Gram-positive organisms.