Essential oil of Origanum minutiflorum exhibits anti-inflammatory and antioxidative effects in human bronchial cells and antimicrobial activity on lung pathogens

Abstract

Introduction: Oregano essential oil (OEO) is one of the most widely used essential oils worldwide due to its huge therapeutic benefits. Nevertheless, data on the effects of the endemic species Origanum minutiflorum, also known as wild or Turkish oregano, is scarce. On the other hand, various chronic lung diseases, characterised by persistent inflammation, oxidative stress, and common bacterial infections, do not have effective pharmacological therapy. Hence, the aim of this study is to examine the effects of wild oregano essential oil (WOEO) on human bronchial epithelial cells and lung pathogens. Methods: We provided a detailed chemical composition of WOEO using GC-MS and GC-FID analysis. Anti-inflammatory effects of WOEO were analysed using the qRT-PCR and ELISA methods, while antioxidative properties were examined by using the dichlorofluorescein assay in BEAS-2B cells. Antibacterial activity was tested on lung pathogens by using the agar diffusion assay. Results: The major constituents of WOEO, analysed in this study, were carvacrol, linalool, p-cymene, γ-terpinene, and (E)-caryophyllene. We found that treatment with WOEO attenuated LPS-induced IL8 gene expression and hydrogen peroxide-induced oxidative stress in BEAS-2B cells. Moreover, WOEO showed an inhibitory effect on pathogenic bacteria Acinetobacter baumannii and highly resistant Klebsiella pneumoniae commonly seen in healthcare-associated pneumonia. Conclusion: Our work presents new insights into the anti-inflammatory, antioxidative, and antimicrobial properties of WOEO which may be used as a simple and local treatment in various chronic lung diseases.