title: Antibacterial Investigation of Thyme Essential Oil and Its Main Constituents in Combination with Tetracycline.
abstract: The chemical composition and antibacterial activity of Thymus glabrescens Willd. (thyme) essential oil were examined, as well as its association with tetracycline. The antibacterial activities of geraniol and thymol, the main constituents of T. glabrescens oil, were also determined. Gas chromatography and gas chromatography/mass spectrometry were used to analyze the chemical composition of the oil. The antibacterial activities of the oil, geraniol, and thymol were investigated by the broth microdilution method. The interactions of the essential oil, geraniol, and thymol with tetracycline, toward five selected strains, were evaluated using the microdilution checkerboard assay. Oxygenated monoterpenes were the most abundant compound class in the oil (57.14%), with geraniol (22.33%) as the major compound. The essential oil exhibited in vitro antibacterial activity against all tested bacterial strains. The combinations, essential oil-tetracycline and thymol-tetracycline, produced synergistic interaction to a greater extent compared with geraniol-tetracycline association. All synergistic combinations reduced the minimum effective dose of the antibiotic and, consequently, minimized its adverse side effects.
authors.affiliation: 1 Department of Pharmacy, Faculty of Medicine, University of Niš , Niš, Serbia .
authors.forename: Dragoljub L
authors.initials: DL
authors.lastname: Miladinović
authors.affiliation: 1 Department of Pharmacy, Faculty of Medicine, University of Niš , Niš, Serbia .
authors.forename: Budimir S
authors.initials: BS
authors.lastname: Ilić
authors.affiliation: 2 Center for Microbiology, Institute for Public Health , Niš, Serbia .
authors.forename: Branislava D
authors.initials: BD
authors.lastname: Kocić
authors.affiliation: 3 Clinic for Endocrinology, Diabetes and Diseases of Metabolism, Clinical Center Niš , Niš, Serbia .
authors.forename: Vojislav M
authors.initials: VM
authors.lastname: Ćirić
authors.affiliation: 4 Department of Sanitary Chemistry, Institute for Public Health , Niš, Serbia .
authors.forename: Dejan M
authors.initials: DM
authors.lastname: Nikolić
mesh_terms: D000080462:Acyclic Monoterpenes; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects*; D002849:Chromatography, Gas; D008401:Gas Chromatography-Mass Spectrometry; D008826:Microbial Sensitivity Tests / Q000379:methods; D009822:Oils, Volatile / Q000737:chemistry / Q000494:pharmacology*; D010936:Plant Extracts / Q000737:chemistry* / Q000494:pharmacology; D010938:Plant Oils / Q000737:chemistry / Q000494:pharmacology; D013729:Terpenes / Q000737:chemistry / Q000494:pharmacology*; D013752:Tetracycline / Q000494:pharmacology*; D046930:Thymus Plant / Q000737:chemistry*
chemical_list: D000080462:Acyclic Monoterpenes; D000900:Anti-Bacterial Agents; D009822:Oils, Volatile; D010936:Plant Extracts; D010938:Plant Oils; D013729:Terpenes; D013752:Tetracycline; C007836:geraniol
keywords: T. glabrescens; Thymol; antibiotic; geraniol; synergistic interactions