Design, Synthesis, and Evaluation of New Sulfone Derivatives Containing a 1,3,4-Oxadiazole Moiety as Active Antibacterial Agents

This study aimed to synthesize some new sulfone derivatives containing a 1,3,4-oxadiazole moiety and investigate their in vitro antibacterial activities against Xanthomonas oryzae pv. oryzae ( Xoo) and Xanthomonas axonopodis pv. citri ( Xac), the pathogens of rice bacterial leaf blight and citrus canker, respectively, by performing turbidimeter tests. Antibacterial bioassay results showed that compound 6d revealed excellent bioactivities against Xoo and Xac, with the 50% effective concentration (EC₅₀) values of 0.17 and 1.98 μg/mL, respectively, compared with thiodiazole copper (121.82 and 77.04 μg/mL, respectively) and bismerthiazol (92.61 and 58.21 μg/mL, respectively). Meanwhile, greenhouse-condition trials indicated that, compared with thiodiazole copper and bismerthiazol, compound 6d more effectively reduced rice bacterial leaf blight.