Research Of Anti-Methicillin-Resistant Staphylococcus Aureus Active Components In Urtica Dioica

Objective We carried out research on the antibacterial activity of Urtica dioica and screened out the sites with obvious antibacterial activity.We also identified its chemical composition and make preliminary research on its antibacterial machine.In order to find a natural antimicrobial with less side effects and unique bacteriostatic mechanism,so as to provide theoretical basis for further research and application of this resource.Methods(1)The strains were successfully identified and activated by the methods of plate streaking and polymerase chain reaction.(2)The minimum inhibitory concentration,diameter of inhibitory zone of the drug on experimental strains were determined by TTC staining and K-B method,respectively.(3)By the modern chemical separation methods such as systematic solvent extraction,macroporous resin chromatography,and silicagel column chromatography combined with K-B and TTC staining for the separation of components against methicillin-resistant Staphylococcus aureus detections,the strongest antibacterial activity components of Urtica dioica were screen out.The nuclear magnetic resonance were used to identify the structures of the separated active compounds.(4)The growth curve of bacteria affected by drugs was determined by turbidimetry.(5)Changes of soluble polysaccharides,nucleic acids,and protein content in bacterial solution were detected to investigate the effect of drugs on on the structural integrity of cells.(6)Changes in phosphorus metabolism and membrane potential of bacterial solution were used to detect the effect of drugs on bacterial metabolism.Results(1)SA,MRSA,ST5-MRSA and ST239-MRSA were activated successfully.(2)In this study,based on the guidance of pharmacological activity,a total of 9 compounds were isolated from the Urtica dioica.They were vanillic acid(compound 1),quercetin-3-O-glucopyranoside(compound 2),uosolic acid(compound 3),vanillin(compound 4),salicyl alcohol(compound 5),kaempferol(compound 6),quercetin(compound 7),quercetin-3-O-galactoside(compound 8),isorhamnetin(compound 9).(3)Compared with compound 1,the diameter of bacteriostatic zone of compound 4 and compound 5 decreased,and the difference was not statistically significant(P>0.05),the diameter of bacteriostatic zone of other compounds on the experimental strains decreased significantly(P<0.05 or P<0.01);The results of the minimum inhibitory concentration showed that the MIC of compound 1 on the experimental strains were all 1mg/m L;The MIC of compound 4 on SA,MRSA,ST5-MRSA and ST239-MRSA were 1,1.5,1,and 1mg/m L,respectively;The MIC of compound 5 on SA,MRSA,ST5-MRSA and ST239-MRSA were 1.75,1.75,1.5,and 1.5mg/m L,respectively.(4)Compared with the normal group,the exponential growth period of bacteria in the experimental group with compounds 1,4 and 5 was significantly inhibited(P<0.05 or P<0.01),and the bacterial growth was always at a low level.(5)Compared with the normal group,the total sugar concentration in the culture solution significantly increased with the extension of the action time after adding compounds 1,4 and 5(P<0.05 or P<0.01).Compared with the normal group,when the bacteria interacted with compounds 1,4 and 5,the absorbance of bacterial suspension under 260 nm increased,and the difference was statistically significant(P<0.05 or P<0.01);the content of nucleic acid increased significantly and the protein content in the bacterial suspension increased significantly(P<0.05 or P<0.01).(6)Compared with the normal group,when the bacteria interacted with compounds 1,4 and 5,the phosphorus consumption in the experimental group decreased significantly with the extension of action time(P<0.05 or P<0.01),the average fluorescence intensity in the bacterial solution decreased significantly(P<0.05 or P<0.01),and the membrane potential decreased.Conclusion 1.Nine compounds were successfully isolated,and among the isolated monomers,five were flavones,three were phenols,and one was an organic acid.2.The isolated compounds 1,4,and 5 have better anti-MRSA activity.It may play a bacteriostatic effect by inhibiting bacterial division growth in logarithmic growth phase;destroying the bacterial cell structure,causing the contents including sugars,nucleic acids and proteins to leak;affecting phosphorus metabolism and destroying the membrane potential of bacterial cells,affecting cell metabolism.