Harzianolides H-J: Three New Butenolides Isolated from the Fungus Trichoderma harzianum

Background: Marine fungi have been recognized as new sources for the discovery of valuable secondary metabolites, providing lead compounds for drug discovery and development. Objective: The objective of this study was to isolate and identify the secondary metabolites from the marine-derived fungus Trichoderma harzianum ZN-4 and evaluate their antifungal activity. Methods: Fungus strain Trichoderma harzianum ZN-4 was initially fermentated using a PDB liquid medium. Subsequently, extensive chromatographic methods were applied to isolate the fermentation cultures of ZN-4, and the chemical structures of isolate compounds were elucidated by 1D and 2D NMR, ECD, and HRESIMS. The antifungal activity was evaluated using the broth microdilution method. Results and Discussion: Three new butenolides, harzianolides H–J (1–3), were isolated from T. harzianum ZN-4, and cultivated on a sterilized PDB medium. Activity evaluation showed that compounds 1−3 exhibited potent antifungal activity with MIC values of 12.5−100 μg/mL against the phytopathogenic fungus Pestalotiopsis theae. Conclusion: This study not only enriched the structural diversity of the harzianolide family but also revealed their anti-P. theae activity, which may be potential antifungal agents.