Longibrachiamide A, a 20‐Residue Peptaibol Isolated from Trichoderma longibrachiatum Rifai DMG‐3‐1‐1

Longibrachiamide A (1), a new 20‐residue peptaibol, along with three known ones (2–4), were isolated from the fungus Trichoderma longibrachiatum Rifai DMG‐3‐1‐1, isolated from a mushroom Clitocybe nebularis (Batsch) P. Kumm, which was collected from coniferous forest of northeast China in our previous work. The structure of longibrachiamide A (1) was determined by its NMR and ESI‐MS/MS data, the absolute configuration of 1 was further determined by Marfey's analyses. And the complete NMR data of 2–4 were also reported for the first time. The similar CD spectra of 1–4 showed that they all had mixed 310‐/α‐helical conformations. Compounds 1–4 showed strong cytotoxicities against BV2, A549 and MCF‐7 cells, and also showed moderate inhibitory effects against the tested Gram‐positive bacteria, including MRSA T144 and VRE‐10.