Synthesis And Biological Activity Of Myricetin Derivatives Containing Quinazolinon

In this paper,we used myricetin as raw material and introduced the substituted quinazolinone group into the structure of the natural product myricetin,and obtained forty-five quinazolinone-containing myricetin derivatives.The structures of these derivatives were identified by ¹H NMR,¹³C NMR and HRMS.The antibacterial and antiviral activities were tested by the turbidimetric assays and the half-leaf blight spot methods.Based on the test results,the preliminary mechanism of action of some target compounds was studied.The main findings of the study are presented below:1.The results of the antibacterial activity test showed that compounds L17,L18,T1 and T5 had good inhibitory activities against Xanthomonas axonopodis pv.citri（Xac）.The EC₅₀values of these compounds were 18.1,16.9,23.6 and 22.4μg/m L,respectively,which were better than the control drugs bismerthiazol（BT）（62.2μg/m L）and thiodiazole copper（TC）（97.5μg/m L）;Compound L18 had better inhibitory activity against Pseudomonas syringae pv.actinidiae（Psa）,with an EC₅₀value of28.1μg/m L,which was smaller than BT（81.0μg/m L）and TC（128.0μg/m L）;Compounds L11,L18,T5 and T15 had better inhibitory effects on Xanthomonas oryzae pv.oryzae（Xoo）,with EC₅₀values of 42.5,20.4,18.5 and 21.6μg/m L,respectively,which were much better than BT（63.7μg/m L）and TC（86.1μg/m L）.Scanning electron microscopy（SEM）experiments revealed that the morphology of Xac changed from plump to broken,with the concentration of compound L18increasing.Therefore,it is judged that compound L18 can inhibit the normal growth of Xac to a certain extent.2.The results of antiviral activity test showed that compounds L11,T2,T11and T15 had good inhibitory activity against tobacco mosaic virus（TMV）.In terms of curative activity,the EC₅₀values were 261.0,190.0,227.3 and 166.9μg/m L,respectively,which were superior to the commercial drug ningnanmycin（NNM）（319.7μg/m L）;In terms of protective activity,the EC₅₀values were 205.8,228.7,178.9 and 130.5μg/m L,respectively,which were superior to NNM（341.3μg/m L）.The K_dvalues of compounds L11,T2,T11,and T15 for TMV CP were 0.012,0.052,0.054 and 0.024μM,respectively,which were much smaller than NNM（2.726μM）by the microscale thermophoresis test（MST）.This indicates that the above compounds have stronger binding ability to TMV CP than NNM.For the compound T15 with better protective activity,some simple related immune activation mechanisms were explored.By exploring its effects on the contents of chlorophyll and peroxidase（POD）in the tested tobacco,compound T15 can enhance the disease resistance of tobacco to a certain extent.