Phytochemical Profiling and Biological Activities of Origanum onites L. Growing in Balıkesir, Türkiye

Abstract

Background and Aims: Origanum onites L., ordinarily known as Turkish oregano, have long been used in traditional medicine due to its therapeutic properties. This study aimed to investigate the phytochemical composition, antimicrobial activity, and cytotoxic effects of the essential oil and methanolic extract obtained from O. onites cultivated in the Bal & imath;kesir region of T & uuml;rkiye. Methods: O. onites essential oil (OOEO) and methanolic extract were prepared through hydrodistillation and Soxhlet extraction, respectively. The antimicrobial potential was assessed using the broth microdilution method against a panel of bacterial and yeast strains. The cytotoxicity of A549 human lung adenocarcinoma cells was evaluated via 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The chemical profile of OOEO was determined by gas chromatography and mass spectrometry (GC-MS). Results: The essential oil exhibited antimicrobial activity with a minimum inhibitory concentration (MIC) of 120 pg/mL against Escherichia coli and Staphylococcus epidermidis, 240 pg/mL against Klebsiella pneumoniae, Staphylococcus aureus and Proteus mirabilis, 3900 pg/mL against Candida parapsilosis, and 7800 pg/mL against Candida tropicalis. Additionally, the cytotoxic effects were assessed on A549 cells, with Half-maximal inhibitory concentration (IC50) values of 0.01 mg/mL for the OOEO and 0.03 mg/mL for the methanolic extract, indicating greater potency of the OOEO. Furthermore, oxidative stress markers suggested that both extracts could induce oxidative stress, as evidenced by the significant depletion of glutathione levels. GC-MS analysis of OOEO revealed a high concentration of bioactive constituents, particularly carvacrol (61.9%) and thymol (16.0%), both known for their potent biological effects. Conclusion: These findings highlight the potential of OOEO as an adjuvant therapy for lung cancer, underscoring the need for further research to explore their mechanisms of action and therapeutic applications.