Tetradehydrohalicyclamine A and 22-hydroxyhalicyclamine A, new cytotoxic bis-piperidine alkaloids from a marine sponge Amphimedon sp.

Two new 3-alkylpiperidine alkaloids, tetradehydrohalicyclamine A (2) and 22-hydroxyhalicyclamine A (3), have been isolated from a marine sponge Amphimedon sp. as cytotoxic constituents. Their structures were elucidated by spectroscopic analysis. Compounds 2 and 3 inhibited growth of P388 cells with IC50 values of 2.2 and 0.45 mug/mL, respectively.