Neopetrocyclamines A and B, polycyclic diamine alkaloids from the sponge Neopetrosia cf exigua.

Two new polycyclic alkaloids, neopetrocyclamines A and B (1 and 2), along with the known metabolites papuamine (3) and haliclonadiamine (4), were isolated from the Indonesian sponge Neopetrosia cf exigua. Neopetrocyclamine A contains a formamidinium moiety, a rare functional group. While these compounds share the same basic biosynthetic building blocks, the size of the ring system differs in 1 and 2 because of the formamidinium moiety. Biological evaluations of 1–4 revealed that papuamine is cytotoxic against glioblastoma SF-295 cells (GI50 = 0.8 μM).