new imidazole alkaloids and zinc complexes from the micronesian sponge leucetta cf. chagosensis. | four new imidazole alkaloids, 2-5, along with the known isonaamidine b (1) were isolated from a pacific sponge, leucetta cf. chagosensis, collected from yap, federated states of micronesia. among these, 4 and 5 are zinc complexes derived from isonaamidine b and isonaamidine d. the structures of the new compounds were elucidated from spectral data. isonaamidine d (3) showed weakly antifungal activity against aspergillus niger with mic = 100 micrograms/ml. | 1998 | 9544567 |