Inhibition of Tobacco Bacterial Wilt with Sulfone Derivatives Containing an 1,3,4-Oxadiazole Moiety

A series of new sulfone compounds containing the 1,3,4-oxadiazole moiety were designed and synthesized. Their structures were identified by H-1 and C-13 nuclear magnetic resonance and elemental analyses. Antibacterial bioassays indicated that most compounds exhibited promising in vitro antibacterial bioactivities against tobacco bacterial wilt at 200 mu g/mL. The relationship between structure and antibacterial activity was also discussed. Among the title compounds, 5'c:, 5'h, 5'i, and 5, could inhibit mycelia growth of Ralstonia solanacearum in vitro by approximately 50% (EC50) at 39.8, 60.3, 47.9, and 32.1 mu g/mL, respectively. Among them, compound 5) was identified as the most promising candidate due to its stronger effect than that of Kocide 3000 [Cu(OH)(2)] within the same concentration range. Field trials demonstrated that the control effect of compound 55 against tobacco bacterial wilt was better than that of the commercial bactericide Saisentong. For the first time, the present work demonstrated that sulfone derivatives containing 1,3,4-oxadiazole can be used to develop potential bactericides for plants.