Chemical composition, antimicrobial activity, kinetics and mechanism of action of Himalayan-thyme (Thymus linearis Benth.)

ABSTRACT

In this study, antimicrobial activity of the essential oil (EO) and extracts of Himalayan-thyme (Thymus linearis Benth.) was evaluated against nine pathogenic microbial strains using disc diffusion and microdilution broth assays. The chemical composition of the EO was determined by gas chromatography-flame ionisation detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The molecular mechanism of action of the EO was investigated against three pathogenic bacteria (Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis) and three fungal strains (Candida albicans, Candida glabrata, and Candida tropicalis) using the assays of protein leakage, and DNA and RNA leakage through the membrane. Major components of the EO were thymol (54.9%), γ-terpinene (16.6%) and p- cymene (5.2%). The EO showed broad-spectrum potent antibacterial and antifungal activity (MIC 240–990 µg/mL) against test strains. The EO damaged cell membranes and altered cell membrane permeability of test microorganisms. The EO showed a time- and dose-dependent bactericidal and fungicidal effect. It could act as a promising antimicrobial agent due to its short killing time.

KEYWORDS:

• Thymus linearis
• Lamiaceae
• essential oil composition
• antibacterial activity
• antifungal activity
• mechanism of action

Acknowledgments

The authors are thankful to Council of Scientific and Industrial Research (CSIR) New Delhi, India for financial support. We also thank the Director, CSIR-CIMAP for encouragement and support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Council of Scientific and Industrial Research (CSIR) New Delhi.