Five undescribed cyclopeptides from Cordyceps militaris

Ustiloxins I-M (1-5), five undescribed cyclopeptides bearing a 15-membered macrocyclic skeleton, were isolated from Cordyceps militaris. The structures of 1 and 5 were identified by spectroscopic and crystallographic methods, whereas the structures of 2-4 were assigned by spectroscopic and computational approaches. Biological evaluation of all the compounds toward human triple-negative breast cancer cells revealed that compounds 4 and 5 are toxic with IC₅₀ values of 64.29 μM and 28.89 μM, respectively.