New bromotyrosine-derived alkaloids, purealidins B (1) and C (2), have been isolated from the Okinawan marine sponge Psammaplysilla purea and their structures elucidated on the basis of spectroscopic data. Purealidin B (1) showed antibacterial activity, while purealidin C (2) exhibited antifungal and antineoplastic activities. © 1991.