Evaluating the antibacterial properties of essential oils from Arugula, Thyme, Cinnamon, Mint, and Myrrh against pathogenic bacteria

Abstract

Five essential oils-arugula, thyme, cinnamon, mint, and myrrh-were purchased from a local market Riyadh, Saudi Arabia, and evaluated for their antibacterial properties against four significant human pathogens: Escherichia coli, Staphylococcus aureus, Streptococcus pyogenes, and Bacillus subtilis. The antibacterial effectiveness of these essential oils was assessed using the disc diffusion method. The minimum inhibitory concentration (MIC) was determined through a twofold serial dilution technique. Chemical profiling of the selected essential oils was conducted using gas chromatographymass spectrometry (GC-MS). The findings revealed that all essential oils exhibited varying degrees of antibacterial activity. Mint and myrrh oils, in particular, showed strong inhibitory effects across all tested pathogens. The MIC values for mint and myrrh oils were found to be between 3.125 and 12.5 μl/ml, while the other essential oils ranged from 25.0 to 100 μl/ ml. In the chemical analysis of mint oil, eight primary compounds were identified: limonene, eucalyptol, menthone, menthol, alpha-terpineol, isomenthol, germacrene D, and germacrene D-4-ol, with menthol being the predominant component at 68.9%. Conversely, myrrh oil was found to contain eight chemical constituents: monegene, menthofuran, beta-elemene, caryophyllene, curzene, cadinene, germacrene B, and furanoeudesma- 1,3-diene, with curzene as the leading compound at 45.9%. This research highlights the potent antibacterial properties of mint and myrrh essential oils as natural alternatives to conventional antibiotics, addressing the urgent issue of antibiotic resistance. Their broad-spectrum activity, surpassing ciprofloxacin against certain pathogens, and low MIC values demonstrate their high efficacy and potential as cost-effective antimicrobial agents.