Agelamadins C–E, Bromopyrrole Alkaloids Comprising Oroidin and 3‑Hydroxykynurenine from a Marine Sponge Agelas sp.

Three structurally unique bromopyrrole alkaloids, agelamadins C–E (<b>1</b>–<b>3</b>), were isolated from a marine sponge Agelas sp. Agelamadin C (<b>1</b>) possesses a hybrid structure of oroidin and 3-hydroxykynurenine connected through a dihydro-1,4-oxazine moiety. Agelamadins D (<b>2</b>) and E (<b>3</b>) are a C-9/C-10 diastereomer and a 10-epimer of <b>1</b>, respectively. The structures of <b>1</b>–<b>3</b> were elucidated on the basis of spectroscopic analysis as well as application of a PGME method and a TDDFT ECD calculation. Antimicrobial activity of <b>1</b>–<b>3</b> was evaluated