Ectyoplasin, a novel cytotoxic cyclic peptide from sponge.

A new cyclic heptapeptide, ectyoplasin (), was isolated from a methanol extract of the sponge . The planar structure of , cyclo(-Leu-Asn-Ala-Val-Thr-Pro-Gly-), was determined by one and two-dimensional NMR spectroscopy and high-resolution tandem mass spectrometry. Its absolute stereochemistry was solved by Marfey's method. The assays show that ectyoplasin () possess significant cytotoxic activity (2.9 - 23.5 µM) against the cell lines, DU-145 (human prostate cancer), Jurkat (human T-cell acute leukaemia), MM144 (human multiple myeloma), HeLa (human cervical carcinoma) and CADO-ES1 (human Ewing's sarcoma). The DU-145 cell line showed apoptotic cell death in response to ectyoplasin () treatment.