Chemical Composition and In Vitro Cytotoxicity of Endemic Thymus brachychilus Jalas Against Human Breast Adenocarcinoma (MCF-7, HTB-22), Human Lung Adenocarcinoma (A549, CRM-CCL-185), and Human Glioblastoma Cells (U-118 MG, HTB-15)

Objective:Thymus have 341 species in the world and 46 species in Türkiye, 19 of them are endemic. Thymus species are used for stomachache, cold, shortness of breath, cough, bronchitis, diabetes in Aladağlar (Niğde). In this study, essential oil (EO) analysis of Thymus brachychilus, liquid chromatography/mass spectrometry (LC/MS) analysis of ethanol extract, and its effects on the cell lines mentioned in the title were investigated for the first time.Methods:The endemic Thymus brachychilus Jalas was collected from Aladağlar Mountains, from 3,290 meters. Voucher specimens were prepared after the plant species were identified and kept at the herbarium (HERA 1029). 100 g of dried and powdered aerial part of the plant material was distilled for three hours, yielding 0.42 mL of volatile oil using a Clevenger-style apparatus. The 3.28 g ethanol extract was obtained from 100 g plant. An Agilent GC-FID/MS system was used to analyze EO samples. Phenolic compounds of the extract were analyzed using LC-HRMS. MTT assay was used to evaluate the cytotoxicity of EO and ethanol extract.Results:Thymol (48.11%), p-cymene (12.92%), carvacrol (11.14%) were the major components of the EO. For the extract, the IC50 values were calculated to be between 1.64-15.76 μg/mL, while the values of IC50 were calculated between 68.94-101.2 μg/mL for the essential oil.Conclusion:Both the ethanol extract and the EO caused cell death in the tested cell lines. However, the extract appeared to be more effective compared to the essential oil. Besides that, a difference between the cell types could be seen, where the U118 MG neuronal cells appeared to be the most sensitive cell line.