The Design, Synthesis And Preliminary Study Of The Mechanism Of Action Of Purine-substituted Chalcone Derivatives With Anti-plant Virus Activity

Chalcone is a kind of natural flavonoid.Because of its extensive biological activity,it has been widely used in medicine and pesticides and has become one of the hot spots of natural product structure derivatization.Recently,pesticide scientists have founded that chalcone compounds have good antiviral activity,but their control effect is unsatisfactory.In order to find highly effective,low-toxic,and environmentally friendly anti-plant virus agents.In this paper,chalcone as lead compound,then introduces purine and benzenesulfonamide active groups with antiviral activity through the principle of bioactive substructure linkage.A series of novel chalcone derivatives containing a purine and benzenesulfonamide moiety were designed and synthesized.The anti-TMV,-CMV and–PVY activities of target compounds were evaluated through the half-leaf method,with the N.tabacum cv and C.amaranticolor as model plants.The interaction models of the target compounds and TMV coat protein were analysed through molecular docking.A preliminary study on the mechanism of target compounds to tobacco mosaic virus was carried out.The work of this paper is summarized as follows:1.Basing on studies of chalcone and purine compounds,with chalcone as the lead compound,introduces purine and benzenesulfonamide active groups with antiviral activity through the principle of bioactive substructure linkage,and 33 novel chalcone derivatives contains a purine and benzenesulfonamide moiety were designed and synthesized,all the target compounds were characterized by ¹H NMR and ¹³C NMR and HRMS.2.The anti-TMV,-CMV and-PVY activities of target compounds were evaluated through the half-leaf method,and the bioactivity test showed that the most of compounds exhibited good inhibitory activity,against TMV and CMV.Compounds d1and d9 showed good inhibitory activity to the three aspects of TMV in treatment,protection and inactivating,and the inhibitory rates were 54.8,55.7 and 64.1,57 and88.5,88.6%respectively,which was similar to that of ninnanmycin（50.2,60.8,90.6%）.Compounds d1,d2,and d9 revealed good inhibitory activities（curative,protective,and inactivating）,against CMV,which was superior to that of ribavirin（inhibitory rates were 40.6,51.0,and 70.4%,respectively）,Compound d9 exhibited high inactivating activity,with EC₅₀0 value of 51.65μg/mL,which was similar to that of ninnanmycin（48.98μg/mL）.Compounds d1,d2,d4,d9,d21,and d31 exhibited remarkable curative activities with EC₅₀ values of 386.22,662.11,655.00,347.34,351.01 and 320.38μg/mL,respectively,which were superior to those of ninnanmycin（699.62μg/mL）and ribavirin（1240.16μg/mL）.Compounds d1,d2,d9,d22,d29,and d31 showed protective effects at EC₅₀ values of 381.30,499.10,353.34,388.44,292.16,450.87 and438.19μg/mL,which were superior to those of ninnanmycin（468.19μg/mL）and ribavirin（501.99μg/mL）.3.The binding status of target compounds d5,d9,d17 and control agent ribavirin to TMV coat protein（TMV-CP）were observed by molecular docking.The binding mode between ribavirin and TMV-CP were observed,which formed three conventional hydrogen bonds with amino-acid residues of ASP266,ASP219,and GLU222 into the active site of TMV-CP,with the distances of 2.77?,2.19?,and 1.98?,respectively.Compound d9 formed four conventional hydrogen bonds with amino-acid residues of SER138,GLY137,ASN72,and ARG134,with the distances of 3.00?,2.47?,2.73?,and 2.68?,respectively.Compound d5 and d17 did not have hydrogen bonds,only existed non-hydrogen bond interaction.The results of docking showed that it have strong hydrogen bonding interaction between compound d9 and TMV-CP.4.In order to further verify the results of molecular docking,we measured the binding capacity between compound and TMV-CP by fluorescence spectroscopy（FT）and microthermofluorescence（MST）.The results showed that there was a strong binding capacity between the compound d9 and TMV-CP,and the the association constant K_a was 1.58×10⁵ L/mol and the dissociation constant K_d was 12.16μM.