Comparative in vitro evaluation of the antimicrobial properties of essential oils from Lamiaceae, Cistaceae, and Asteraceae families against Enterococcus faecalis

Author(s): Rafail Fokas, Vasiliki Koukousianou, Anastasia Strataki, Paraskevi S Sinou, Fotini N Lamari, Apostolos Vantarakis

The urgent need for effective antimicrobial agents to combat bacterial infections and the growing problem of antibiotic resistance has driven research into natural alternatives. This study investigates the antimicrobial properties of thirteen essential oils (EOs) from the Lamiaceae, Cistaceae, and Asteraceae families against the pathogen Enterococcus faecalis. The chemical composition of these EOs was analysed using gas chromatography-mass spectrometry (GC-MS), while their antimicrobial activities were assessed through the disk diffusion method. Additionally, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for each EO. Our results revealed that oregano, thyme, and dittany EOs exhibited strong antimicrobial effects, with inhibition zones ranging from 19.5 to 50 mm and MIC values as low as 0.15 mg/mL, alongside MBC values of 0.30 mg/mL. In contrast, peppermint, rosemary, rockrose, and immortelle EOs showed considerably weaker antimicrobial efficacy, with larger MIC and MBC values and smaller inhibition zones. These findings underscore the potential of oregano, thyme, and dittany EOs as promising antimicrobial agents.