Discovery of novel sulfonamide derivatives containing pinacolone moieties as fungicide candidates against Botrytis cinerea

Background: Botrytis cinerea is one of the most serious plant diseases and severely threatens agricultural production. The rapidly intensifying resistance makes most commercial chemical fungicides lose control efficacy. Developing new fungicides with novel structures and modes of action is an effective measure to solve this problem.

Results: In this work, 29 novel sulfonamide compounds containing pinacolone scaffolds were designed and synthesized based on the active substructure splicing strategy. The biological activity assay on three kinds of Botrytis cinerea strains manifested that these compounds exhibit moderate to excellent antifungal activity. Compounds 3a-1 and 3a-11 displayed the highest in vitro antifungal activity similar to control agents carbendazim, procymidone, and boscalid. Compound 3c had the lowest EC₅₀ value of 1.96 μg/mL against strain PJ-02 compared to boscalid (6.90 μg/mL). Bioassay results on strawberry fruits and tomato pots indicated that compounds 3a-1 and 3a-11 also possess superb in vivo antifungal activity compared to control agents. The electronic conductivity measurement results showed that compound 3a-1 can significantly increase the membrane permeability of Botrytis cinerea mycelium. Scanning electron microscopy observation revealed that compound 3a-1 could cause the Botrytis cinerea mycelium to twist and break, and inhibit mycelium branching. Density functional theory calculation and molecular electrostatic potential distribution were also used to analyze the activity mechanism of target compounds.

Conclusion: Due to their excellent antifungal activity against Botrytis cinerea, these novel sulfonamide derivatives containing pinacolone scaffolds could be considered qualified fungicide candidates. Preliminary exploration of the mechanism suggests that this kind of compound may possess a novel mode of action. © 2025 Society of Chemical Industry.