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The Scientific World Journal
Volume 2014 (2014), Article ID 826219, 12 pages
Research Article

An In Vitro Synergistic Interaction of Combinations of Thymus glabrescens Essential Oil and Its Main Constituents with Chloramphenicol

1Department of Pharmacy, Faculty of Medicine, University of Niš, 18000 Niš, Serbia
2Center for Microbiology, Institute for Public Health, 18000 Niš, Serbia
3Clinic for Endocrinology, Diabetes and Diseases of Metabolism, Clinical Center Niš, 18000 Niš, Serbia
4Center of Chemistry, ICTM, University of Belgrade, 11000 Belgrade, Serbia

Received 23 August 2013; Accepted 20 November 2013; Published 28 January 2014

Academic Editors: L. Kong and D. Ruzek

Copyright © 2014 Budimir S. Ilić et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The chemical composition and antibacterial activity of Thymus glabrescens Willd. (Lamiaceae) essential oil were examined, as well as the association between it and chloramphenicol. The antibacterial activities of geraniol and thymol, the main constituents of T. glabrescens oil, individually and in combination with chloramphenicol, were also determined. The interactions of the essential oil, geraniol, and thymol with chloramphenicol toward five selected strains were evaluated using the microdilution checkerboard assay in combination with chemometric methods. Oxygenated monoterpenes were the most abundant compound class in the oil, with geraniol (22.33%) as the major compound. The essential oil exhibited in vitro antibacterial activity against all tested bacterial strains, but the activities were lower than those of the standard antibiotic and thymol. A combination of  T. glabrescens oil and chloramphenicol produced a strong synergistic interaction (FIC indices in the range 0.21–0.87) and a substantial reduction of the MIC value of chloramphenicol, thus minimizing its adverse side effects. The combinations geraniol-chloramphenicol and thymol-chloramphenicol produced synergistic interaction to a greater extent, compared with essential oil-chloramphenicol association, which may indicate that the activity of the thyme oil could be attributed to the presence of significant concentrations of geraniol and thymol.