The Synthesis And Biological Activity Of Piperazine Derivatives Containing Heterocycles

As one of the nitrogen-containing heterocyclic compounds,quinazoline and pyrimidine derivatives possessing broad spectrum of medicinal and agricultural bioactivities,such as anticancer,anti-inflammatory,antioxidant,antispasm,antibacterial,antispasm,antimicrobial and antiviral activities,have been as one of the research hotspots to develop high efficiency,low toxicity and safe green pesticide.Meanwhile,1,4-pentadien-3-one are also widely concerned by the world with its antimicrobial,antiviral,anticancer activities and low mammalian toxicity.Two aspects were mainly studied in this thesis.The first one is the synthesis and antibacterial activities of piperazine compounds containing quinazoline and pyrimidine scaffolds,the second one is biological evaluation and plausible action mechanism of pyridinium-decorated 1,4-pentadien-3-one derivatives.1 Piperazine compounds containing quinazoline and pyrimidine scaffolds were synthesized and characterized by ¹H NMR,¹³C NMR,¹⁹F NMR and MS.The biological activities of all the title compounds against Xanthomonas oryzae pv.oryzae,Xanthomonas axonopodis pv.citri and Ralstonia solanacearum were examined using the turbidimeter test in vitro.The results showed that most of the compounds exhibited excellent antibacterial activities,especially for Xanthomonas oryzae pv.Oryzae.Further studied suggested that the EC₅₀ values of most of the compounds were ranging from 0.419 to 66.8?g/mL,which was much better than the control agent Bismerthiazol(EC₅₀0 value was 92.6?g/mL).When quinazoline ring were replaced by 6,7-dimethoxyl,compound C7 demonstrated the best antibacterial inhibition effects against Xanthomonas oryzae pv.Oryzae.with EC₅₀0 value up to 0.419?g/mL.Besides,at the concentration of 50?g/mL,these compounds showed good inhibition effect toward Xac,compounds C3,C6,C7,C8,C16,C24 and C25 were bioactive against Xanthomonas axonopodis pv.citri with the suppression values ranging from 95.3%to 100%,which was better than that of Thiodiazole copper?30.2%?.Furthermore,at the concentration of 50?g/mL,compounds C3,C4,C12,C15,C24 and C25 showed good inhibition rate againstRalstoniasolanacearumwiththesuppressionvaluesof70.9%,58.0%,62.5%,65.0%,54.4%and 51.2%,which was better than that of Thiodiazole copper?36.4%?2.A series of pyridinium-tailored 1,4-pentadien-3-one compounds were constructed and characterized by ¹ HNMR,¹33 CNMR.The antimicrobial activities of all the title compounds against against Xanthomonas oryzae pv.oryzae,Xanthomonas axonopodis pv.citri and Ralstonia solanacearum were examined using the turbidimeter test in vitro.Futher research found that these compounds exhibited the best inhibition activities against Xoo,with the EC₅₀ values ranging from 0.504²3.2?g/mL,which was much better than the control agent Bismerthiazol(EC₅₀0 value was 92.61?g/mL).Besides,Compounds D₁,D₂,D₅,E₁,E₅ and G₂were bioactive against Xanthomonas axonopodis pv.citri with the suppression values above 80%,which was better than that of Thiodiazole copper?30.2%?.Furthermore,Compounds D₁,D₂,D₃,E₂,E₃,F₁and G3 showed good bioactivity toward Ralstonia solanacearum with the suppression values above 50%,which was better than that of Thiodiazole copper?36.4%?,The antifungal activity of target compounds was tested via the poison plate technique against three phytopathogenic fungal strains including Botrytis cinerea,Fusarium oxysporum,and Sclerotinia Slerotiorum,target compounds demonstrated poor to good antifungal activity.A plausible action mechanism for this kind of compounds was proposed and confirmed by employing fluorescent spectroscopy,fluorescence microscopy,and scanning electron microscopy.