New nitrogenous compounds from a Red Sea sponge from the Gulf of Aqaba

Chemical investigation of an unknown marine sponge, which was collected in the Gulf of Aqaba (Jordan), afforded a new brominated alkaloid 3-amino-1-(2-amino-4- bromophenyl) propan-1-one (1), as well as 7-bromoquinolin- 4(1H)-one (2) which had previously only been reported as a synthetic compound. In addition, caulerpin (6), previously only known to be produced by algae, was likewise isolated. Furthermore, three known alkaloids including (Z)-5-(4-hydroxybenzylidene)-hydantoin, (Z)-6-bromo-3'- deimino-2',4'-bis(demethyl)-3'-oxoaplysinopsin, and 6-bromoindole-3-carbaldehyde (3-5), were also obtained. All compounds were unambiguously elucidated based on extensive 1D and 2D NMR spectroscopy, LCMS, as well as by comparison with the literature and tested for their cytotoxic activity toward the mouse lymphoma cell line L5178Y.