Azo-incorporating Increases Inhibitory Activity of Succinate Dehydrogenase.

Diversity of pesticide discovery provided a solution to resistance. Here, we presented a strategy of azo-incorporating to promote the diverse developments of fungicide. A series of novel fungicides were synthesized by incorporating azobenzene derivatives into fluxapyroxad. Much better in vitro fungicidal activity increases for compound 9d were observed compared to the positive control, fluxapyroxad against Botrytis cinerea and Rhizoctonia solani. Compound 9d (IC50 = 0.03 µM) also had a great enzyme-inhibiting activity increase toward succinate dehydrogenase in comparison with fluxapyroxad (IC50 = 4.40 µM). A comparatively equivalent biological activity was observed between compounds 8a and 9d. SEM analysis helped us to observe clearly the morphology of the fungi before and after active ingredient delivery. Our results of molecular docking analysis, fluorescence quenching analysis, and enzymatic assays demonstrated that compound 8a and 9d act on SDH. An increase in inhibitory activity could be occurring after incorporation of azobenzene, which provided a new strategy for molecular design in pesticide discovery.