Callyaerin G, a new cytotoxic cyclic peptide from the marine sponge Callyspongia aerizusa

From the ethyl acetate fraction of the Indonesian sponge Callyspongia aerizusa extract, a new cyclic peptide named callyaerin G was isolated.Its structure was elucidated by extensive 1D and 2D NMR (1H NMR, TOCSY and ROESY) studies and mass spectrometric data (ESI-and FAB-MS).The stereochemistry was determined by Marfey`s analysis.Callyaerin G was found to exhibit cytotoxic activity when tested against different cancer cell lines.