This work covers the chemical composition and antimicrobial activities of the essential oils isolated from Satureja thymbra and Thymbra spicata analyzed using GC/MS. The main components of S. thymbra oil were thymol (33.8 %), ?-terpinene (30.8 %) and p-cymene (11.8 %). The main components in T. spicata oil were carvacrol (74.5 %) and ?-terpinene (11.2 %). The oils and their main components, thymol and carvacrol, were assayed by applying the microdilution method for antibacterial and antifungal activity against food poisoning, plant, animal and human pathogenic microorganisms. The oil of T. spicata and carvacrol showed the highest antimicrobial activity.

Objectives: The chemical composition, antimicrobial and synergistic effect, and cytotoxic activity of Citrus limon (lemon), Piper nigrum (green pepper) and Melaleuca alternifoila (tea tree) essential oils (EOs) were investigated. Methods: Chemical analyses of essential oils were tested by GC-FID and GC-MS spectroscopy. The antimicrobial activity assay was conducted using microdilution method against several oral bacteria and Candida spp. originating from the humans with oral disorders. The synergistic antimicrobial activity was evaluated using checkerboard method. The cytotoxicity evaluation of EOs was assessed using MTT test. Key findings: Limonene (37.5%) and β-pinene (17.9%) were the major compounds in C. limon oil, β-pinene (34.4%), δ-3-carene (19.7%), limonene (18.7%) and α-pinene (10.4%) in P. nigrum oil and terpinen-4-ol (38.6%) and γ-terpinene (21.7%) in M. alternifolia oil. The broad-spectrum antimicrobial activity was achieved by tested three EOs, with C. limon oil being the strongest against bacteria and M. alternifolia oil strongest against fungi. The EOs demonstrated synergism; their combined application revealed an increase in antimicrobial activity. All tested essential oils showed lower cytotoxic activity in comparison with the positive control, and the obtained results confirmed a dose-dependent activity. Conclusions: The results of this study encourage use of tested EOs in development of a novel agent intended for prevention or therapy of corresponding oral disorders.