Discovery of Antibacterial Compounds against subsp. from a Marine Fungus SCSIO 41202 and the Mode of Action.

Citrus canker, caused by subsp. (), is a severe citrus disease. Currently, copper-containing pesticides are widely used to manage this disease, posing high risks to the environment and human health. This study reports the discovery of naturally occurring anti- compounds from a deep-sea fungus, SCSIO 41202, and the possible mode of action. The ethyl acetate extract of was subjected to bioassay-guided isolation, resulting in the discovery of eight anti- compounds (-) with minimum inhibitory concentrations (MICs) ranging from 0.078 to 0.625 mg/mL. The chemical structures of these eight metabolites were determined by integrative analysis of various spectroscopic data. Among these compounds, Asperporonin A () and Asperporonin B () were identified as novel compounds with a very unusual structural skeleton. The electronic circular dichroism was used to determine the absolute configurations of and through quantum chemical calculation. A bioconversion pathway involving pinacol rearrangement was proposed to produce the unusual compounds (-). Compound exhibited an excellent anti- effect with a MIC value of 0.078 mg/mL, which was significantly more potent than the positive control CuSO (MIC = 0.3125 mg/mL). Compound inhibited cell growth by disrupting biofilm formation, destroying the cell membrane, and inducing the accumulation of reactive oxygen species. In vivo tests indicated that compound is highly effective in controlling citrus canker disease. These results indicate that compounds -, especially , have the potential as lead compounds for the development of new, environmentally friendly, and efficient anti- pesticides.