Marine natural products play an important role in biopesticides. Seven new secondary metabolites with different structural classes, including two cycloheptapeptides, scortide A (1) and scortide B (2), two 19-nor-diterpenoids, talascortene H (3) and talascortene I (4), two diterpenoid acids, talascortene J (5) and talascortene K (6), and one triterpenoid, talascortene L (7) were isolated and identified from the sea-anemone-derived endozoic fungus Talaromyces scorteus AS-242. Their structures were comprehensively assigned by spectroscopic data analysis, single-crystal X-ray diffraction, tandem mass spectrometry, and electronic circular dichroism (ECD) calculations. The result of the antimicrobial assay demonstrated that compounds 1 - 6 have inhibitory activity against several human, aquatic, and plant pathogens with minimum inhibitory concentration (MIC) values ranging from 1 to 64 μg/mL. Specially, compounds 2 and 4 showed significant activities against the pathogenic fungus Curvularia spicifera with the MIC value of 1 μg/mL, providing an experimental basis of 2 and 4 with the potential as lead compounds to be developed into biopesticides.
Keywords: Antimicrobial activities; Cycloheptapeptides; Deep-sea seamount-derived fungus; Talaromyces scorteus; Terpenoids.
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