Stylissamides E and F, Cyclic Heptapeptides from the Caribbean Sponge Stylissa caribica

2010-04-23T00:00:00Z (GMT) by Christine Cychon Matthias Köck
In addition to the four known stylissamides, A (1), B (2), C, and D, two new cyclic heptapeptides, stylissamides E (3) and F (4), were isolated from the Caribbean sponge Stylissa caribica. The structures of 3 and 4 were elucidated from a combination of mass spectrometric and NMR spectroscopic data as cyclo-(cis-Pro1-Tyr2-trans-Pro3-Ala4-Ile5-Gln6-Ile7) for stylissamide E (3) and cyclo-(trans-Pro1-cis-Pro2-Phe3-Asp4-trans-Pro5-Arg6-Phe7) for stylissamide F (4).