Design, Synthesis And Biological Activity Of Vanillin Derivatives Containing 1,3,4-thiadiazole Structure

In this paper,we chosen the natural product vanillin as the lead structure,introducing 1,3,4-thiadiazole structure to design and synthesize series novel vanillin derivatives containing a 1,3,4-thiadiazole moiety.The antibacterial activity was evaluated of the target compound against Xanthomonas oryzae pv.oryzae?Xoo?and Xanthomonas oryzae pv.oryzicola?Xoc?in vitro by the turbidity method.Meanwhile,the control efficiencies against rice bacterial leaf blight were carried out under greenhouse conditions via the leaf-cutting method.The preliminary antibacterial mechanism of the compounds with good antibacterial activity was studied.The following is a summary of the main work:1.With the natural product vanillin as the lead structure and the introduction of1,3,4-thiadiazole structure to obtained thirty-four novel vanillin derivatives containing 1,3,4-thiadiazole moiety.The structures of the target compounds were characterized by ¹H nuclear magnetic resonance?¹H NMR?,¹³C nuclear magnetic resonance(¹³C NMR)and high-resolution mass spectrum?HRMS?2.The antibacterial activity was evaluated of the target compounds against Xanthomonas oryzae pv.oryzae?Xoo?and Xanthomonas oryzae pv.oryzicola?Xoc?in vitro by the turbidity method.The results indicate,compounds 12,14,17,18,27,28,and 29 had excellent inhibitory activities against Xoo,with the EC₅₀values of38.74,33.73,33.25,31.78,16.03,28.47,and 3.14?g/m L,respectively,which were much better than thiodiazole copper?87.03?g/m L?and bismerthiazol?67.64?g/m L?.Meanwhile,compounds 17,18,27,28 and 29 had excellent inhibitory activity against Xoc,with the EC₅₀values of 35.49,26.54,27.69,36.47 and 8.83?g/m L,respectively,superior to thiodiazole copper?108.99?g/m L?and bismerthiazol?79.26?g/m L?.3.The control efficiencies against rice bacterial leaf blight were carried out under greenhouse conditions via the leaf-cutting method.The results showed that compound 29 demonstrated good controlling effect against rice bacterial leaf blight under greenhouse condition.The protective and curative efficiency was 49.34%and40.96%at the concentration of 200?g/m L,respectively,as well as commercial agents thiodiazole copper?46.43%and 43.98%?,and bismerthiazol?56.97%and 48.30%?.4.The preliminary antibacterial mechanism of the compounds with good antibacterial activity was studied.The results show that compound 29 reduced the exopolysaccharides production of Xoo,and broke cell membranes,thereby reduced the pathogenicity of Xoo.