Synthesis And Biological Evaluation Of 1,2,3-triazole Derivatiesas Fungicides

1,2,3-triazole derivaties are associated with a broad spectrum of biological activities,including antibacterial,antiviral,anticancer activities,but less in new pesticide research.A series of 1,2,3-triazole derivatives with anti-plant pathogenic fungi activity were designed and synthesized in the previous work.Compound 5p exhibited significant anti-phytopathogenic activity including Rhizoctonia solani,Sclerotinia sclerotiorum,Fusarium graminearum and Phytophthora capsici,with the EC50 values of 0.18,2.28,1.01,and 1.85 ?g/mL,and in vivo testing demonstrated that 5p was effective in the control of rice sheath blight,rape sclerotinia rot and fusarium head blight.It was found that the halogen substitution on the benzene had a key effect on the activity based on the 3D-QSAR model,1,2,3-triazole derivatives was further optimized.All the synthesized 48 1,2,3-triazoles were new.The synthesized triazoles were characterized by 1H-NMR,13C-NMR,MS,elemental analysis and X-ray single-crystal diffraction and evaluated for their antifungal activity against R.solani,S.sclerotiorum,F.graminearum and P.capsica.Compound 8d displaying potent antifungal activity against each of these plant pathogenic fungi were found,with the EC50 values of 0.86,1.66,0.28,5.83?g/mL.In vivo testing demonstrated that 8d was effective in the control of rice sheath blight,rape sclerotinia rot and fusarium head blight.At a concentration of 200?g/mL,the in vivo protective effect of 8d against rice sheath blight could reach 52.9%,The protectiv effect of 7d and 8d against rape sclerotinia rot was 67.5%and 64.3%at 200 ?g/mL,respectively.The protectiv effect of 8d against fusarium head blight at 200 ?g/mL was 66.6%.Quantitative structure activity relationship studies for the synthesized compounds were also carried out to check the effect of various substituents and substitution position in parent compound on antimicrobial activity.The results showed that the addition of positively charged groups at the o-position on the benzene ring of phenylhydrazine was beneficial to increase the activity,while the addition of negatively charged groups at the p-position is beneficial to increase the activity.The addition of the benzene ring groups on the 1,2,3-triazole could be detrimental to the activity,increasing the position of the p-position of the 1,2,3-triazole and the p-position of the benzene ring of the phenylhydrazine increased the activity;adding the hydrophobic group at thep-position of the triazole ring and the p-position on the phenylhydrazine ring which was beneficial to the activity,And the addition of hydrophilic groups at the two benzene rings was beneficial to the activity.The compound 8d not only inhibited the hyphal growth of F.graminearum,but also caused a series of marked morphological and structural alterations of the hyphae.These changes included irregular swelling and Excessive branching of the hyphae,considerable thickening of the hyphal cell walls,particularly at the hyphal tip region.In conclusion,1,2,3-triazole derivatives can be further studied as a fungicide candidate.