Design,Synthesis And Properties Of Functional Molecules Based On Two Natural Products Containing Sulfur

In recent years,the overuse of chemical pesticides has made the problems of pesticide residues and pollution in the soil more and more serious.Therefore,it is particularly important to find high-efficiency and environmentally friendly new green pesticides.In this project,sulfur-containing natural products are used as lead compounds to design and synthesize two new and highly effective anti-tobacco mosaic virus（TMV）inhibitors.The mechanism of action between the target compound and the tobacco mosaic virus capsid protein（TMV CP）was preliminarily explored,and the spectral properties of some compounds containing Schiff base structures were studied.The research content mainly includes the following three parts:Part 1:As the leader,the N,S and O atoms of the natural product L-cysteine was modified.The effects of three structural sites on the biological activity of cysteine and its derivatives were systematically investigated.Anti-TMV biological activity showed that cysteine and its derivatives showed moderate to excellent anti-TMV activity,and most of cysteine and its derivatives were better than commercial ribavirin at 500μg/mL.Structure-activity relationship studies have shown that the introduction of substituents on S and N atoms of cysteine has no significant effect on the anti-TMV activity,but the introduction of larger sterically hindered alkyl groups on S atoms is beneficial to the improvement of its activity.Cysteine and its derivatives can inhibit the assembly of TMV by inducing 20S CP polymerization in the mechanism studies.Cysteine and its derivatives can interact with TMV CP to achieve good antiviral effects through molecular docking and fluorescence titration.Different from the anti-TMV activity,although cysteine and its derivatives have certain inhibitory effects on 14 kinds of plant pathogenic bacteria,the bactericidal activity is not significant.Part 2:The highly active chiral thiourea compounds screened in the previous period were used as lead compounds,and 40 new chiral thiourea compounds were designed and synthesized.The structure-activity relationship and mechanism of action of this kind of chiral thiourea compounds have been deeply studied.Most of the compounds have excellent anti-TMV activity in biological activity.Under the same test conditions,some compounds were better than commercial varieties of Ningnanmycin,and generally better than commercial varieties of ribavirin.In general,this type of chiral thiourea compounds have broad-spectrum bactericidal activity,and some compounds have an inhibitory rate of more than 90%against Rhizoctonia solani.Mechanism of action studies have shown that such chiral thiourea compounds can depolymerize 20S CP and inhibit the assembly of TMV particles.Molecular docking studies have proved that there are interaction hydrogen bonds between chiral thiourea compounds and some amino acid residues of TMV CP.The fluorescence titration data of compounds with TMV CP have shown that the compounds selectively increased/decreased the fluorescence intensity of TMV CP due to its different structure,which have indirectly proved that there are multiple modes of action between the compound and TMV CP.Part 3:The spectral properties of different substituted salicylaldehyde Schiff base chiral thiourea compounds were investigated systematically because of their unique structural characteristics.The probes can realize the selective recognition of Zn²⁺in acetonitrile solution,and the detection limit can reach as low as 22.7 ppb.Trace detection of Zn²⁺can be achieved in the presence of nitrate ions.Through Job′s plot,X-ray single crystal diffraction analysis and ¹H NMR titration analysis,the coordination mechanism of this type of chiral thiourea Schiff base compounds with Zn²⁺were determined.The fluorescent probe provides O,N and S to complex with Zn²⁺in a ratio of 1:1,and NO₃^-also participates in the coordination.The L-Zn NO₃ complexes were formed by probe and Zn（NO₃）₂ can selectively recognize H₂PO₄^-,which was proved to be an“OFF-ON-OFF”fluorescent probe with good application prospects.