Antibacterial Activity Of Zunyimycin C Against Methicillin-resistant Staphylococcus Aureus

Objective: Anti-MRSA activity analysis of the anthrone antibiotics of zunyimycin C,to provide experimental basis for the analysis of its activity mechanism.Methods:1.The prokaryotic expression plasmid p ET32a-fab F,which encodes the target gene fab F of β-ketoacyl-ACP synthetase II from the clinical isolates of MRSA,was constructed by DNA recombination and transformed into Escherichia coli expression strain Rosetta(DE3)to construct genetically engineered bacteria p ET32a-fab F-R.2.The gene engineering strain p ET32a-fab F-R heterologously expressed recombinant protein r Fab F were inducted by IPTG,the expression of target protein was detected by SDS-PAGE,and affinity chromatography purificated by Ni-NTA.3.Detected the fluorescence quenching of interaction between zunyimycin C and recombinant protein r Fab F by fluorescence spectrophotometry,and to determine whether zunyimycin C played a role through Fab F.4.The MIC and MBC values of zunyimycin C against MRSA clinical isolates were determined,and the clinical isolates of MRSA were determined to be sensitive to zunyimycin C and drug resistance.5.The pharmacokinetic parameters,such as half-life,of zunyimycin C in SD rats were detected by TLC.6.The SD rats model of MRSA infection was used to detect the effect of zunyimycin C on the lethal dose of MRSA in SD rats.Results:1.The genetically engineered strain p ET32a-fab F-R were successfully constructed,optimized the conditions of the genetically engineered bacteria expression the recombinant protein r Fab F and purified it.2.Initially identified the interaction between zunyimycin C and the recombinant protein rFabF.3.Zunyimycin C was found to have the anti-MRSA effects with a MIC value of 0.41 μg/ml while MBC value of 6.30 μg/ml,for the bactericidal power(ratio MBC/MIC)was 15.37.4.The half life(t1/2)of zunyimyicn C in SPF rats was 6.3 h.5.Zunyimycin C can significantly prolong the survival of MRSA-infected SD rats,and has a significant dose-response relationship(p<0.05).Conclusion:Zunyimycin C showed strong bactericidal activity against clinical isolates of MRSA,had a good protective effect on MRSA-infected SD rats and had certain clinical application potential.