Synthesis and Antibacterial Evaluation of New Sulfone Derivatives Containing 2-Aroxymethyl-1,3,4-Oxadiazole/Thiadiazole Moiety

Sulfones are one of the most important classes of agricultural fungicides. To discover new lead compounds with high antibacterial activity, a series of new sulfone derivatives were designed and synthesized by introducing the aroxymethyl moiety into the scaffold of 1,3,4-oxadiazole/thiadiazole sulfones. Antibacterial activities against three phytopathogens (Xanthomonas oryzae pv. oryzae,Ralstonia solanacearum,Xanthomonas axonopodis pv. citri.) were assayed in vitro. As compared to the control of commercial fungicides and some reported sulfone fungicides, seven compounds5I-1–5I-7exerted remarkably higher activities with EC50values ranging from 0.45–1.86 μg/mL againstX. oryzaeand 1.97–20.15 μg/mL againstR. solanacearum. Exhilaratingly,5I-1,5I-2and5I-4displayed significant in vivo activity againstX. oryzaewith protective effect of 90.4%, 77.7%, and 81.1% at 200 μg/mL, respectively, much higher than that exhibited by Bismerthiazol (25.6%) and Thiadiazole-copper (32.0%). And the differential phytotoxicity of active derivatives was preliminarily checked. The results demonstrated that derivative of 2-aroxymethyl-1,3,4-oxadiazole/thiadiazole sulfone can serve as potential alternative bactericides for the management of plant bacterial diseases.Keywords:synthesis;1,3,4-oxadiazole/thiadiazole sulfone;aryloxymethyl;antibacterial activity;structure-activity relationship