Nine new bromotyrosine alkaloids, purealidins J—R(1-9), have been isolated from the Okinawan marine sponge Psammaplysilla purea and the structures were elucidated on the basis of spectroscopic data. A hydroxy group at C-1 of purealidins M—O (4—6) may be biosynthetically derived from ring-opening of a spirocyclohexadienylisoxazole unit of purealidin J (1), aerophobin-1 (10), and purealidin L (3), respectively. Purealidins N (5), P (7), and Q (8) were cytotoxic to tumor cell lines, while purealidins J (1), K (2), P (7), and Q (8) showed moderate inhibitory activity against epidermal growth factor (EGF) receptor kinase.