Libyan Thymus capitatus essential oil: Antioxidant, antimicrobial, cytotoxic and colon pathogen adhesion-inhibition properties

Abstract

© 2015 The Society for Applied Microbiology. Aims: In the present work, the Libyan wild-growing Thymus capitatus essential oil (EO) was evaluated for its biological properties. Methods and Results: Carvacrol (68·19%) and thymol (12·29%) were found to be the main compounds of the oil. Antioxidant properties, determined by 2,2-diphenylpicrylhydrazyl (DPPH) assay, revealed that IC50 values were 119, 403 and 105 μg ml-1 for oil, thymol and carvacrol respectively. Microdilution method showed strong antibacterial and especially antifungal potential. Tetrazolium (MTT) colorimetric assay indicated moderate cytotoxicity towards human cell lines MRC-5, HCT 116 and HT-29 (IC50 = 30-150 μg ml-1). In adhesion-inhibition assay oil and main compounds reduced adhesion of Escherichia coli and Listeria monocytogenes on colon cells HT-29 (51 and 39% of inhibition against L. monocytogenes and E. coli respectively). Conclusions: Essential oil of Th. capitatus showed moderate cytotoxic activity, together with excellent antimicrobial effect, in particular against fungi, and significant potential to reduce pathogen colonization in colon. Significance and Impact of the Study: This is the first report that EO of Th. capitatus could protect against colonization of pathogens to colon epithelium. Thymus capitatus from Libya should be recognized as possible new source of natural antioxidants, antimicrobials as well as possible source of new chemotherapeutics.