Trichodermic acids from an endophytic Trichoderma sp. and their antifungal activity against the phytopathogen Botrytis cinerea

Abstract

Phytopathogen Botrytis cinerea is a necrotrophic pathogen with a wide host range, which causes considerable economic losses in agriculture. Consequently, it is necessary to find safe and effective antifungal agents against B. cinerea from natural sources. In this study, eight octahydronaphthalene derivatives (1−8) including four new natural products named trichodermic acids E − H (1−4), were isolated from an endophytic fungus Trichoderma sp. Their structures were determined by analysis of their nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectra (HR-ESI-MS) and by electronic circular dichroism (ECD) data. All compounds showed some extent of antifungal activities against B. cinerea with minimum inhibitory concentration (MIC) values ranging from 4 to 64 μg/mL. Notably, compound 8 showed significant inhibition with an MIC of 4 μg/mL, which was visually confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These findings provide a potential application of trichodermic acids as natural “hit” fungicides in agriculture.