Nagelamides X-Z, dimeric bromopyrrole alkaloids from a marine sponge Agelas sp.

Three new dimeric bromopyrrole alkaloids, nagelamides X-Z (1-3), were isolated from a marine sponge Agelas sp. Nagelamides X (1) and Y (2) possess a novel tricyclic skeleton consisting of spiro-bonded tetrahydrobenzaminoimidazole and aminoimidazolidine moieties. Nagelamide Z (3) is the first dimeric bromopyrrole alkaloid involving the C-8 position in dimerization. The structures of 1-3 were elucidated on the basis of spectroscopic data. Nagelamides X-Z (1-3) exhibited antimicrobial activity.