Myriastramides A-C, new modified cyclic peptides from the Philippines marine sponge Myriastra clavosa

Chemical investigation of the Philippines marine sponge Myriastra clavosa has resulted in the isolation of three new cyclic octapeptides, myriastramides A (1), B (2), and C (3). The structures of compounds 1-3 were assigned based on extensive NMR spectroscopic analyses and a series of degradation and derivatization studies. (C) 2003 Elsevier Ltd. All rights reserved.