Four new dimeric pyrrole-2-aminoimidazole alkaloids have been isolated from the Pacific marine sponges Agelas cf. mauritiana and Phakellia sp. They include the unusual C2 symmetrical benzosceptrins A (4) and B (5), which each possess a unique benzocyclobutane skeleton and nagelamides S (6) and T (7). Their structures and relative configuration were elucidated from spectroscopic data. Plausible biogenetic paths for these compounds are also proposed in this paper.

Three new diterpene alkaloids, agelasine J (3), agelasine K (4), and agelasine L (5), were isolated from the marine sponge Agelas cf. mauritiana collected in the Solomon Islands. The structures of these compounds were elucidated by physical data analyses. They displayed in vitro antimalarial activity against Plasmodium falciparum.