Phenolic Compounds, Antioxidants and Antibacterial Activity of Some Native Medicinal Plants Against Pseudomonas aeruginosa

Background & Objective: Traditional medicines have a wide range of pharmacological properties. This work was aimed to investigate the antimicrobial effect of Thymus vulgaris, Matricaria chamomilla, Melissa officinalis and Rhus coriaria extracts against clinical isolates of Pseudomonas aeruginosa. Materials and Methods: 180 P. aeruginosa clinical isolates were examined. disc diffusion method as well as MIC and MBC of the methanol and alcohol herbal extracts was measured. Furthermore, microtiter plate assay evaluated biofilm development in the P. aeruginosa isolates. The free radical scavenging activity of the plant extracts against 2,2-diphenyl-1-picrylhydrazyl (DPPH) was determined. Results: Results showed that P.aeruginosa strains were resistant to more than three different classes of antibiotics. Our results demonstrated that the MBC values of ethanol and methanol extracts of thyme was 43.75 mg/ml, and 31.25 mg/ml, respectively. The highest MIC and MBC values were observed for the thyme and Lemon balm had the lowest MIC and MBC values. Our study showed that thyme extract was exhibited to be the most efficient plant extracts against P.aeruginosa. The scavenging activity of thyme, chamomile, sumac and lemon balm was 91.05 ± 1.10, 89.55 ± 0.70, 64.65 ± 1.95 and 80.1 ± 0.30 %, respectively Conclusion: These findings may help in reducing our dependence on antibiotics and handle infections of opportunistic pathogens more efficiently. Further studies are required to distinguish the most important phytochemical compounds and estimate their antibiofilm activities and their mechanisms of action.