Antifungal cyclopeptolide from fungal saprophytic antagonist Ulocladium atrum

The saprophytic fungus Ulocladium atrum Preuss is a promising biological control agent for Botrytis cinerea in greenhouse- and field-grown crops. However, despite its known potent antifungal activity, no antifungal substance has yet been reported. In an effort to characterize the antifungal substance from U atrum, we isolated an antibiotic peptide. Based on extensive spectroscopic analyses, its structure was established as a cyclopeptolide with a high portion of N-methylated amino acids, and its 1H and 13C chemical shifts were completely assigned based on extensive 1D and 2D NMR experiments. Compound 1 exhibited potent antifungal activity against the plant pathogenic fungus Botrytis cinerea and moderate activity against Alternaria alternate and Magnaporthe grisea.