Antibacterial Activity And Mechanism Of Fraxetin On Escherichia Coli

Cortex Fraxini is a typical natural coumarin compound with effective component of fraxetn.Researches show that it has bacteriostatic action, but the antibacterial mechanism of fraxetn isunknown. We study the bacteriostatic action and antibacterial mechanism of fraxetn based inE.coli strains. The results showas following:1. Fraxetin has strong inhibitory activity and sterilization effect in E.coli. The minimuminhibition concentration of fraxetin is0.04mg/mL. When concentration of fraxetin isup to0.05mg/mL, the sterilizing rate reaches highest68.2%after72h.2. The results of conductivity experiment, content of macromolecules exeriment,scanning electron micoscopy experiment and transmission electron micoscopyexperiment show that fraxetin can cause damage effect on the membrane of E.coli,butthe effect is not obvious. It indicates that the main target of fraxetin is not in cellmembrane of E.coli.3. Compared with the control group, the amount of solube protein in E.coli hassignigicantly improved after fraxetin effecting in fraxetin group. The total sobuleprotein of bacteria decreases by59%than the control group with fraxetin after20h.4. The results of agarose gel electrophoresis experiment show that fraxetin has inhibitionon topoisomeras I and II, but the effect is not obvious. It indicates that main target offraxetin is not on topoisomeras I and II of E.coli.5. The results of plasmid elimination experiment show that fraxetin can eliminate thepiasmid in E.coli and the effection of plasimd elimination is enhancded with theduration extension.Fraxetin is obviously inhibition to E. coli bacteria. Its main effect is to reduce thecontent of soluble protein And it also indicates that inhibition mechanism of fraxetin isinhibiting the synthesis of protein and its physiological functions and thus suppressingnormal growth and inducing somatic death.