Improved antifungal activity and reduced aquatic toxicity of fludioxonil by complexation with β-cyclodextrin

Abstract Poor water solubility results in limited fungicidal bioavailability and poses a great risk to non-target organisms due to the use of organic solvent in formulation processing. Here, the water solubility of fludioxonil (Flu) was improved by generating an inclusion complex with β-cyclodextrin (β-CD) at 1:1 host-guest stoichiometric ratio. The formation of the inclusion complex was confirmed by SEM, XRD, FT-IR, DSC, and 1H-NMR spectra. Molecular docking simulation found that Flu was imbedded into the β-CD cavity, folded, and centrally aligned inside. In addition, Flu/β-CD displayed increased soil mobility, sustained release behavior, and a 2.75-fold increase of the fungicidal activity against Botrytis cinerea. Importantly, the prepared inclusion complex exhibited decreased acute toxicity to phytoplankton (Chlorella vulgaris), zooplankton (Daphnia magna), and fish (Danio rerio) than technical Flu. This study provided useful information for the rational use of Flu in agriculture, as well as the reduction of ecological risk to the aquatic environment.