Cytotoxic alkylpiperidine alkaloids from the Brazilian marine sponge Pachychalina alcaloidifera

Four bis-piperidine alkaloids, madangamine F (1), haliclonacyclamine F (2). and arenosclerins D (3) and E (4), have been isolated from the marine sponge Pachychalina alcaloidifera and have been identified by analysis of spectroscopic data. The alkaloids displayed cytotoxic activity against different cancer cell lines. These results support the hypothesis of a common biogenetic origin for the Haplosclerida bis-piperidine and bis-pyridine alkaloids.