The Effect of Carvacrol as the Main Polyphenolic Compound of Thymus eriocalyx Ronniger Jalas on the Inhibition of Bacteria growth

Introduction: Due to the increasing resistance of bacterial diseases to antibiotics, it is essential to identify medicinal plants that contain antibiotics and antibacterial. This study aimed to compare the efficacy of pasture thyme essential oil with common antibiotics against Escherichia coli and Staphylococcus aureus bacteria. Materials & Methods: The study, conducted in 2022 at Payame Noor University, investigated the antibacterial properties of Thymus eriocalyx essential oil. Leaves and stems were collected from Kermanshah highlands, and essential oil was extracted using hydrodistillation. Gas chromatography-mass spectrometry identified the components. The oil was tested against Escherichia coli and Staphylococcus aureus at concentrations of 0.48 to 250 µg/mL using liquid and solid methods, as well as the disk diffusion method. Results were compared with antibiotics (ampicillin, ciprofloxacin, erythromycin, and cefixime) at specific concentrations. Data were analyzed using SPSS V.23 with a significance level of 0.01. Results: Tests with gas chromatography-mass spectrometry showed that carvacrol (66.96%) is the main ingredient in this type of thyme, and a total of 42 active substances were found. Essential oil concentrations of 250, 125, and 62.5 mg/ml were more effective than the chosen antibiotics in inhibiting both bacterial strains. The minimum bactericidal concentration for Escherichia coli and Staphylococcus aureus was determined to be 62.5 and 7.81 mg/ml, respectively. Conclusion: The essential oil of Thymus eriocalyx demonstrated greater effectiveness against Staphylococcus aureus than Escherichia coli. Due to its significant antibacterial and antiseptic properties compared to antibiotics, further studies on its efficacy in animal models are recommended.