Chemical preparation, degradation analysis, computational docking and biological activities of novel sulfonylureas...

Based on the previous finding that a substitution at 5-position of the benzene ring is favorable to enhance the degradation rates of sulfonylurea herbicides, a total of 16 novel 2,5-disubsituted sulfonylurea compounds were chemically synthesized and fully characterized by means of ¹H NMR, ¹³C NMR, HRMS and X-ray diffraction. By using HPLC analysis, the degradation behavior of M03, a compound belonging to this family, was studied and confirmed that chlorsulfuron itself is not a degraded product of the 2,5-disubstituted sulfonylureas. Inhibition constants against plant acetohydroxyacid synthase (AHAS) were determined for selected compounds, among which SU3 showed seven times stronger activity against the mutant W574L enzyme than chlorsulfuron. Molecular docking suggested that the substituted group at 5-position of benzene ring is likely to interact with the surrounding residues Met200 and Asp376 of AtAHAS. From the greenhouse herbicidal assay and crop safety test, SU5 and SU6 are considered as herbicide candidates to control dicotyledon weeds in corn, while SU3 is likely to be a promising candidate to control dicotyledon weed species and barnyard grass in wheat. The present research has therefore provided some new insights to understand the structure-activity relationships of herbicidal sulfonylureas with di-substitutions at benzene ring.