Design, synthesis, and antibacterial activity of novel amide derivatives containing a sulfone moiety.

Twenty-four amide compounds containing a sulfone moiety were synthesized and the antibacterial activity of the target compounds was tested. Some compounds show excellent antibacterial activity. For example, compound AC4 exhibited broad antibacterial activity with the EC50 of 0.55 mg/L for Xanthomonas axonopodis pv. citr (Xac), and 0.48 mg/L for Xanthomonas oryzae pv. oryzae (Xoo). In the greenhouse, compound AC4 with a concentration of 200 mg/L had good protective activity (39.3%) and curative activity (42.2%) against bacterial leaf blight, both were superior to the commercial antibacterial thiodiazole-copper (19.2% and 31.8%) and bismerthiazol (27.4% and 23.1%). The compound AC4 can inhibit the normal growth of Xoo by inhibiting the virality factors of Xoo (motility, exopolysaccharides, and biofilms). At the same time, molecular docking results showed that compound AC4 could interact with exopolysaccharides and quorum sensing-related proteins. This result was further supported by relative gene expression analysis. In addition, the compound AC4 can also increase membrane permeability, induce intracellular reactive oxygen species (ROS) levels to rise, and cause the surface of Xoo to change. The compound AC4 can be further studied as a potential antibacterial agent and this structure will continue to be optimized.