18-Residue Peptaibiotics from the Suaeda glauca-Derived Fungus Acremonium persicinum and Their Antifungal Potential against Botrytis cinerea.

Fungal natural products have shown potential to control the resistance of Botrytis cinerea to synthetic fungicides. Bioassay-guided isolation from the Suaeda glauca-derived fungus Acremonium persicinum had obtained four novel 18-residue peptaibiotics, persicins A-D (1-4), showing antifungal potential against fungicide-resistant B. cinerea CJ-8. Their structures were elucidated through spectroscopic analyses and the modified Marfey's method. The representative persicin A (1) inhibited spore germination and prevented gray mold on table grapes. Studies on its antifungal mechanisms against B. cinerea CJ-8 revealed that persicin A could disrupt membrane integrity and fluidity, enhance membrane permeability, and induce oxidative stress. Persicin A also impaired intracellular Ca2+ homeostasis and then induced a decrease of the mitochondrial membrane potential (MMP). Moreover, persicin A inhibited mitochondrial respiratory chain complexes I and III, which thus reduced ATP production. In summary, this study first revealed antifungal potential of 18-residue peptaibiotics of the persicin series, which might be developed as biofungicides to control B. cinerea.