Antibacterial Effect and Mechanism of the Ethyl Acetate Extract of Cichorium Intybus L. Against Staphylococcus Aureus

Abstract

Objective: Cichorium intybus L. (CILEAE) has many functions, such as antibacterial, anti-inflammatory, hypoglycemic, lipid-lowering, liver-protection and anti-oxidation. The subject aims to investigate the antibacterial activity and mechanism of the ethyl acetate extract of CILEAE against Staphylococcus aureus (S. aureus). Methods: Firstly, the antibacterial activity of CLEAE against several kinds of frequently pathogenic bacteria was determined by microbroth dilution method, then the antibacterial mechanism was investigated by Scanning Electron Microscope (SEM), permeability of cell membrane, respiratory metabolic pathway, protein band change in SDS-PAGE of soluble protein, and DAPI fluorescence staining. Results: The results of the Minimum Inhibitory Concentration (MIC) showed that CILEAE could significantly inhibit S. aureus and Escherichia coli in the tested concentration range. SEM results showed that 24 h after the application of CILEAE to S. aureus, the surface areas of the phage showed signs of shrinkage, dryness, distortion and deformation, vesicular or irregularly shaped protrusions and contraction of other structures. Culture fluid conductivity results showed that the cell membrane permeability was changed by CILEAE; The results of respiratory metabolism inhibition experiments showed minimal superimposition rates of CILEAE; The results of protein band analysis showed that CILEAE could inhibit protein synthesis in S. aureus, and the results of DAPI fluorescence staining showed that CILEAE treatment significantly reduced the nucleic acid content in vivo. Conclusion: CILEAE has strong bacteriostatic activity against S. aureus. Its bacteriostatic mechanism may be through destroying the integrity of bacterial cell wall and cell membrane, inhibiting bacterial respiratory metabolism, and inhibiting the synthesis of bacterial protein.