Synthesis And Biological Activity Of Chalcone Derivatives Containing Pyridazine (ketone) Or Benzimidazol

This paper designed and synthesized a series of chalcone derivatives containing pyridazine（ketone）and benzimidazole by introducing pyridazine（ketone）and benzimidazole groups with chalcone as the lead compound.All compounds were structurally characterized by NMR and HRMS,and the biological activities of the target compounds were tested.The main research work in this thesis is summarized as follows.1.Twenty chalcone derivatives A containing pyridazine（ketone）were designed,synthesized,and evaluated for their antifungal activities against nine plant fungi,antibacterial activity against three plant bacteria,and antiviral activity against tobacco mosaic virus.The antibacterial results revealed compound A13 showed the best activity against Xanthomonas campestris pv.citri with an EC₅₀ value of 78.89μg/m L,superior to Bismerthiazol(EC₅₀=86.72μg/m L).The antifungal bioactivity results showed that some of the compounds had good bioactivity against fungi such as A9 showed the best bioactivity against Botrytis cinerea with an EC₅₀ value of 8.91μg/m L,which was better than the azoxystrobin(EC₅₀=20.28μg/m L)and A9 also showed good biological activity against Rhizoctonia solani,with an EC₅₀ value of 18.10μg/m L,which was comparable to the azoxystrobin（17.46μg/m L）.The anti-tobacco mosaic virus results showed that some of the compounds had great curative activities,such as A11,A12,A17,and A18,having EC₅₀ values of 190.27,213.48,187.91 and 173.18μg/m L,which were better than that of ningnanmycin（217.70μg/m L）.Compounds A6 and A16 have significant protective activities,whose EC₅₀ values were 233.47 and 211.45μg/m L,respectively,which were better than that of ningnanmycin（238.28μg/m L）.2.Twenty chalcone derivatives B containing benzimidazole were designed and synthesized,and tested for biological activity.The preliminary antibacterial activity tests showed that the target compounds exhibit certain inhibitory activity against Xanthomonas axonopodis pv.citri,Pseudomonas syringae pv.actinidiae,and Xanthomonas oryzae pv.Oryzae,but not satisfactory.The antifungal bioactivity results showed that the inhibition rates of B9 against Colletotrichum gloeosporioides at a concentration of 100μg/m L were 63.23%,which was comparable to the azoxystrobin（63.33%）.The EC₅₀ value of B9 against Colletotrichum gloeosporioides was 46.61μg/m L,which was better than azoxystrobin（56.49μg/m L）.3.In vitro experiments on rice indicated that A9 has certain control effects on rice sheath blight.The antifungal effects of A9 were observed on scanning electron microscope and phospholipid peroxidation,which made the mycelium of Botrytis cinerea produce folds and collapse,and significantly increased the degree of lipid peroxidation of Botrytis cinerea cell membrane.The spore germination assay investigated that A9 has a certain inhibitory effect on spore germination.The possible mechanism of compound A18 against TMV was studied by microscale thermophoresis.The results showed that the dissociation constant of compound A18 interacting with tobacco mosaic virus coat white（TMV-CP）was 0.03258μmol/L,better than Ningnanmycin（4.9161μmol/L）,indicating that the affinity of compound A18 is better than that of Ningnanmycin.