GymnopeptidesC and D, Highly <i>N</i>‑MethylatedFungal Cyclopeptides

An in-depth chemical study of the fungus <i>Gymnopus fusipes</i> led to the discovery of two new cyclooctadecapeptides, gymnopeptides C and D, besides the known gymnopeptides A and B. Spectroscopic studies, as well as Marfey’s analysis, and molecular modeling studies revealed the characteristic structural features of these cyclopeptides. Gymnopeptides A–D demonstrated antiproliferative activity on the A375 human cancer cell line, induced apoptosis by upregulation of caspase-3 activity, and acted as a suppressor of cell migration.