Three cyclic pentapeptides and a cyclic lipopeptide produced by endophytic Fusarium decemcellulare LG53

Abstract

Three new cyclic pentapeptides (1–3) and a known cyclic lipopeptide, fusaristatin A (4), were isolated from an endophytic fungus, Fusarium decemcellulare LG53, harbored in a Chinese medicinal plant Mahonia fortunei. The planar structures of the new compounds were elucidated by extensive spectroscopic analyses using HRMSⁿ and NMR. Their absolute configurations were unambiguously determined by single crystal X-ray diffraction and Marfey's method. Interestingly, compounds 1–3 exhibited no antibacterial activity against a panel of Gram-positive and Gram-negative bacteria. In order to explore the plausible ecological relevance of the compounds within the context of microbial crosstalk and communication strategies, we designed antagonistic and dual-culture assays combined with matrix-assisted laser desorption ionization imaging high-resolution mass spectrometry (MALDI-imaging-HRMS) to investigate the interaction of F. decemcellulare LG53 with another fungal endophyte Glomerella acutata LG52 isolated from the same tissue of the plant. Compound 4 was found to display an allelopathic effect on endophytic G. acutata LG52. Our results provide a proof-of-concept of balanced antagonism that might be occurring between endophytes inhabiting the same plant tissues in distinct ecological niches.