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.