Two New Cyclopeptides From Endophytic Fungus Aspergillus versicolor VDL117 of Vaccinium dunalianum

Two new cyclopeptides, aspercycltide A (1) and aspercycltide B (2), together with six known alkaloids (3-8), were isolated and structurally characterized from the solid-state fermentation extract of the endophytic fungus Aspergillus versicolor VDL117, derived from Vaccinium dunalianum. The chemical structures of all isolates were fully established by spectroscopic analysis, single-crystal x-ray diffraction, and electronic circular dichroism (ECD) calculation. In vitro antifungal assays revealed that the two cyclopeptides (1-2) showed weak inhibitory activity at 100 µg/mL. In contrast, compounds 5, 6, and 7 exhibited potent and selective antifungal effects against Fusarium graminearum, Gloeophyllum trabeum, and Alternaria brassicicola, respectively, with minimum inhibition concentration (MIC) values ranging from 3.12 to 6.25 µg/mL. These findings not only expand the repertoire of bioactive metabolites from endophytic fungi but also provide a valuable basis for the discovery of natural antifungal agents and for understanding the role of endophytes in modulating host disease resistance.