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Aim of the study:MRSA is one of the pathogenic clinical-separated strains causing both hospital and community-acquired infections and for which antibiotic treatment options are compromised.Single antibiotic therapy is becoming less efficient.Coptis chinensis Franch,which has been used for more than three thousand years in China,is mainly adopted traditionally for treating diarrhea,fever and jaundicec.Modern research reveals that Coptis chinensis Franeh has broad-spectrum antimicrobial and antivirus activities.Accordingly,Coptis chinensis Franch was chosen to investigate the anti-MRSA activity.Materials and methods:Drug susceptibility of the strain was investigated by VITEK 2 compact and the resistance gene was determined by PCR amplification and sequencing.Chemical fingerprints were established by Agilent 1200 HPLC.The anti-MRSA activity was investigated by broth microdilution method.And the fluorescence intensity of different growth status of bacteria (stained with resazurin sodium salt) was determined by microplate reader.SAS statistical analysis method was adopt to evaluate the correlation between the chemical fingerprints and anti-MRSA activity.Results:Drug susceptibility test showed that the phenotype of PBP of the strain changed and the DNA of the strain contained mecA gene but no Nora gene.Blast analysis showed that the raecA gene sequence was highly homologous to penicillin-binding protein sequence.All batches of Coptis chinensis Franch showed inhibitive effects on MRSA,and the IC50 ranged from 1196 μg/ml to 2841 μg/ml.Spectrum-effect relationship study revealed that the alkaloid fraction was the main active site,and the primary efficacy constituents of this fraction were berberine,coptisine,palmatine,epiberberine and jatrorrhizine.The results were subsequently validated by the study of liquid chromatography.Conclusions:This study provided reference for the application of Coptis chinensis Franch as a complementary drug in treating anti-drug-resistant strains in the clinic,and it also laid a foundation for the development of natural antibacterial components.