Cytotoxic Scalarane Sesterterpenoids from a Marine Sponge Hippospongia sp.

A new scalarane sesterterpenoid, hippospongide C (1), along with four previously reported known scalarane type sesterterpenes (2-5), were isolated from a sponge Hippospongia sp. The structure of 1 was elucidated on the basis of its spectroscopic data and comparison of its NMR data with those of known analogues. The cytotoxicity of 1-5 against DLD-1, HCT-116, T-47D and K562 cell lines was evaluated. The results showed that compound 4 exhibited potent activity against DLD-1, HCT-116 and T-47D cell lines with IC50 values of 1.3-2.0 mu g/mL. Furthermore, metabolites 1-5 were also found to exhibit significant cytotoxicity towards the K562 cell line with IC50 values of 0.01-2.9 mu g/mL.