Cytotoxic aaptamine derivatives from the South China Sea sponge Aaptos aaptos.

Nine new aaptamine derivatives (1-9), together with three known related compounds (10-12), have been isolated from the South China Sea sponge Aaptos aaptos. The structures of all compounds were unambiguously elucidated on the basis of spectroscopic analyses. Structurally, compound 1 possesses a piperidinyl group fused to a demethyl(oxy)aaptamine moiety, whereas compounds 3-6 share an imidazole-fused 1H-benzo[de][1,6]naphthyridin-2(4H)-one skeleton. The cytotoxic activities of the compounds were evaluated against various human cancer cell lines, and compounds 2, 8, 11, and 12 showed potent cytotoxicities against HL60, K562, MCF-7, KB, HepG2, and HT-29 cells, with IC50 values in the range of 0.03 to 8.5 μM.