The antibiotic Ao58A, which showed strong antifungal activity against some plant pathogenic fungi, was purified from the culture broth and mycelial mats of Micromonospora coerulea strain Ao58 using various chromatographic procedures. The molecular formula of the antibiotic Ao58A was deduced to be C16H23NO4 (M + H, m/z 294.1707) by high-resolution FAB mass spectroscopy. Analyses of 1H NMR, 13C NMR, and 2D NMR spectral data revealed that the antibiotic Ao58A is the glutarimide antibiotic streptimidone, 4-(2-hydroxy-5,7-dimethyl-4-oxo-6,8-nonadienyl)-2,6- piperidinedione. The antibiotic Ao58A was very effective in inhibiting growth of Phytophthora capsici, Didymella bryoniae, Magnaporthegrisea, and Botrytis cinerea in the range ~3-10 μg mL-1 of MICs. In vivo evaluation of the antibiotic Ao58A under greenhouse condition showed strong control efficacies against the development of P. capsici, B. cinerea, and M. grisea on pepper, cucumber, and rice plants, respectively. The antibiotic Ao58A was equally as effective as metalaxyl, vinclozolin, and tricyclazole in the control of these plant diseases. However, it did not show any phytotoxicity on the plants even when treated with 500 μg mL-1.
- Antifungal activity
- Micromonospora coerulea
- Plant disease control
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)