Antimicrobial Activities Of Salvia Miltiorrhiza BGE. And Psoralea Corylifolia L And Antibacterial Mechanism Of Cryptotanshinone And Dihydrotanshinone â… 

This dissertation is composed of three chapters. The first chapter summarized the currentprogress methods of antibacterial mechanism. The second chapter elaborated the antimicrobialactivity of Salvia miltiorrhiza, Psoralea corylifolia L.and their different processed products,including the determination of inhibitory zone, MIC value and IC₅₀value against SA, MRSA andESBLs-SA. The third chapter introduced the antibacterial mechanism of cryptotanshinone anddihydrotanshinoneâ…  against SA, MRSA, ESBLS-SA, including the changes in electricconductivity, concentrations of AKP, protein contents and the changes of protein electrophoreticbands in SDS-PAGE.Chapter1. Research progress on inhibitory mechanismsThe progress of inhibitory mechanisms were summarized.Chapter2. Antimicrobial activity of Salvia miltiorrhiza, Psoralea corylifolia L.and different processed productsDisc Diffusion Methods were used to study the inhibitory zone and MIC value of Salviamiltiorrhiza, and liquid culture methods were used to study IC₅₀value.The inhibitory zone showed that antibacterial activity of fried and alcohol S. miltiorrhizasignificantly increased, antibacterial activity of S. miltiorrhiza carbon still had antibacterialactivity but significantly reduced. Methanol extracts of fried S. miltiorrhiza showed the biggestinhibitory zone of20mm against SA, MRSA and ESBLs-SA at concentration of50mg/mL. TheMIC showed that antimicrobial activity of methanol extracts was best, the inhibitory activity ofpetroleum ether extracts and ethyl acetate extracts was better than that of n-butanol extracts. Thisreflected the antibacterial activity ingredients were mainly in the petroleum ether and ethylacetateextracts. The IC₅₀showed that the ethylacetate extracts of fried S. miltiorrhiza had bestantibacterial activity (IC₅₀=0.26mg/mL) against SA, the ethylacetate extracts of fried S. miltiorrhiza had best antibacterial activity (IC₅₀=0.13mg/mL) against MRSA, the petroleum etherextracts of S. miltiorrhiza and fried S. miltiorrhiza had best antibacterial activity (IC₅₀=0.31mg/mL) against ESBLs-SA.Result showed that different processed products of S. miltiorrhiza had significantl inhibitoryactivity against SA, MRSA and ESBLs-SA. Different processing methods had different impactson the antimicrobial activity of S. miltiorrhiza.Disc Diffusion Methods were used to study the inhibitory zone and MIC value of Psoraleacorylifolia L., liquid culture methods were used to study IC₅₀value.Methanol extract and petroleum ether extract of alcohol P. corylifolia had better antimicrobialactivity which showed the inhibitory zone of12mm against SA, MRSA and ESBLs-SA atconcentration of50mg/mL.The inhibitory activity of methanol extracts and petroleum etherextracts was better than that of ethyl acetate extracts and n-butanol extracts, but processedproducts of ethyl acetate extracts and n-butanol extracts significantly enhanced antibacterialactivity. The MIC showed that the antibacterial activity ingredients of P. corylifolia L. weremainly in the petroleum ether extracts, the MIC value was31.3μg/disc against SA, MRSA andESBLs-SA. The IC₅₀showed that the petroleum ether extracts of alcohol P. corylifolia had bestantibacterial activity (IC₅₀=0.10mg/mL) against SA, the methanol extracts of P. corylifolia hadbest antibacterial activity (IC₅₀=0.16mg/mL) against MRSA, the methanol extracts ofsalt-steamed P. corylifolia had best antibacterial activity (IC₅₀=0.28mg/mL) against ESBLs-SA.The study showed that different processed products of P. corylifolia had significantly inhibitedagainst SA, MRSA and ESBLs-SA. Different processing methods had different impacts on theantimicrobial activity of P. corylifolia, antimicrobial activity of alcohol P. corylifolia increasedsignificantly.Chapter3. Antibacterial mechanism of cryptotanshinone anddihydrotanshinoneâ… Disc Diffusion Methods were used to study the inhibitory zone and MIC value ofcryptotanshinone, liquid culture methods were used to study IC₅₀value. The inhibitory zone ofcryptotanshinone showed that the antimicrobial activity of SA （15mm） was better than that of MRSA （13mm） and ESBLs-SA （13mm） at concentration of5mg/mL. The MIC and IC₅₀showedthat cryptotanshinone had best antibacterial activity (MIC=0.078mg/mL, IC₅₀=0.092±0.03mg/mL) against SA.The antibacterial mechanisms of cryptotanshinone were investigate by determining thechanges in electric conductivity, concentrations of AKP, protein contents, and the changes ofprotein electrophoretic bands in SDS-PAGE.Treated with cryptotanshinone, the electric conductivity, concentrations of AKP, proteincontents were both increased, protein bands in SDS-PAGE were changed obviously. Resultshowed that cryptotanshinone had significantly inhibited against SA, MRSA and ESBLs-SA, andindicated that cryptotanshinone could damage the structure of cell wall and cell membrane, whichresulted in the increase of permeability of cell membrane and release of cell components.Cryptotanshinone could influence the synthesis of bacteria protein, it could destroy the protein orreject the anabolism or expression of the protein, and finally leading to the lost of normalphysiological function of bacterium.Disc Diffusion Methods were used to study the inhibitory zone and MIC value ofdihydrotanshinone â… , liquid culture methods were used to study IC₅₀value. The inhibitory zone ofdihydrotanshinoneâ…  showed that the antimicrobial activity of SA （12mm） was better than that ofMRSA （10mm） and ESBLs-SA （10mm）at concentration of5mg/mL. The MIC showed thatdihydrotanshinone â…  had best antibacterial activity（MIC=0.078mg/mL） against SA. The IC₅₀showed that antimicrobial activity of SA (IC₅₀=0.243±0.01mg/mL) was best, the inhibitoryactivity of ESBLS-SA (IC₅₀=0.280±0.00mg/mL) was better than that of MRSA (IC₅₀=0.539±0.03mg/mL).Treated with dihydrotanshinone I, the electric conductivity, concentrations of AKP, proteincontents were broth increased, protein bands in SDS-PAGE were changed obviously.Results showed that dihydrotanshinone I had significantly inhibited against SA, MRSA andESBLs-SA, and indicated that dihydrotanshinone I could damage the structure of cell wall and cellmembrane, which resulted in the increase of permeability of cell membrane and release of cellcomponents. dihydrotanshinone I could influence the synthesis of bacteria protein, it could destroythe protein or reject the anabolism or expression of the protein, and finally leading to the lost ofnormal physiological function of bacterium.