Preparation And Antibacterial Activity Of Water-soluble Derivatives Of Curdlan

Bacterial infection is a risk factor that threatens human life and health,and the use of antibiotics is the most important method to prevent bacterial infection.However,bacterial resistance and environmental pollution caused by the popularization and application of antibiotics have become prominent problems in current public health.Therefore,the development of safe and efficient non-antibiotic antibacterial substances is an important and urgent issue.In this thesis,curdlan（Curdlan）,trifluoroacetic acid,thioglycolic acid and sodium nitrite were used as starting reactants to prepare water-soluble amino acids through azide,amination,amidation and nitrosation of Curdlan.Aminated curdlan（Cur-NH₂）,trifluoromethyl curdlan（CNC）,thiol curdlan（CNS）and nitroso gum（CNSN）.The cytotoxicity and antibacterial activity of the water-soluble derivatives were studied by CCK-8 method and colony counting method after the physical and chemical properties were determined by nuclear magnetic resonance analysis,infrared spectroscopy,potential potential,thermogravimetric analysis and ultraviolet-visible light analysis system.The results showed that the toxicity of CNC,CNS and CNSN to HEK-A cells was significantly lower than that of Cur-NH₂,and the toxicity of CNC was the lowest.CNC,CNS and CNSN have good bactericidal activity against Gram-negative bacteria（Escherichia coli）and Gram-positive bacteria（Staphylococcus aureus）.When the concentration of Escherichia coli and Staphylococcus aureus was 10⁵CFU/m L,the bactericidal rates of CNC,CNS and CNSN against Escherichia coli were 99.99%,94.68%and 99.99%,respectively,at a sample concentration of 4 mg/m L.The bactericidal efficiencies of Staphylococcus were 99.99%,99.90%and 99.99%,respectively.It can be seen that CNC and CNSN have the best bactericidal effect on Escherichia coli and Staphylococcus aureus.As high-efficiency,low-toxicity,and stable water-soluble antibacterial compounds,they have great potential for development.In this thesis,three safe and effective new water-soluble curdlan antibacterial compounds were prepared and screened,which provided a useful reference for the development of novel non-antibiotic antibacterial materials with high efficiency and low toxicity.