Design, Synthesis, Antibacterial, and Antifungal Evaluation of Phenylthiazole Derivatives Containing a 1,3,4-Thiadiazole Thione Moiety.

To effectively control the infection of plant pathogens, we designed and synthesized a series of phenylthiazole derivatives containing a 1,3,4-thiadiazole thione moiety and screened for their antibacterial potencies against , pv. , as well as their antifungal potencies against , , and . The chemical structures of the target compounds were characterized by H NMR, C NMR and HRMS. The bioassay results revealed that all the tested compounds exhibited moderate-to-excellent antibacterial and antifungal activities against six plant pathogens. Especially, compound possessed the most remarkable antibacterial activity against (EC = 2.23 μg/mL), which was significantly superior to that of compound (EC = 69.87 μg/mL) and the commercial agent Thiodiazole copper (EC = 52.01 μg/mL). Meanwhile, compound displayed the most excellent antifungal activity against (EC = 0.51 μg/mL), which was equivalent to that of the commercial fungicide Carbendazim (EC = 0.57 μg/mL). The preliminary structure-activity relationship (SAR) results suggested that introducing an electron-withdrawing group at the meta-position and ortho-position of the benzene ring could endow the final structure with remarkable antibacterial and antifungal activity, respectively. The current results indicated that these compounds were capable of serving as promising lead compounds.