Isolation and structural elucidation of the human cancer cell growth inhibitory cyclic peptides phakellistatin 4, 5, 6, 7, 8 and 9

摘要

The cytostatic, cyclic peptides; phakellistatin 4, phakellistatin 5, phakellistatin 6, phakellistatin 7, phakellistatin 8 and phakellistatin 9 were isolated from the Western Pacific Ocean sponge Phakellia costata. Structural determination was accomplished by utilizing high-field, 2D-NMR experiments and confirmed by results of FAB-MS/MS studies. The absolute configurations were deduced by analyzing the acid hydrolysates using chiral gas chromatographic analytical techniques. The new cyclic peptides were found to have significant in vitro P388 ED.sub. 50 values which range between 0.18 &mgr;g/ml and 4.1 &mgr;g/ml.