Chemical composition and antimicrobial activity of the essential oil from Satureja horvatii Šilić (Lamiaceae)

The present paper describes the chemical composition and antimicrobial activity of the essential oil of the endemic species Satureja horvatii Šilić, collected in Montenegro. The essential oil was obtained from the aerial parts of the plant by hydrodistillation and analyzed by GC-MS. From the 34 compounds representing 100 % of the oil, the major compound was the phenolic monoterpene thymol (63.37 %). The oil contained smaller amounts of g-terpinene (7.49 %), carvacrol methyl ether (4.92 %), carvacrol (4.67 %), p-cymene (4.52%), a-terpinene (1.81 %), borneol (1.58 %), a-thujene (1.56 %), b-caryophyllene (1.55 %) and b-myrcene (1.44 %). The antimicrobial activity of the essential oil of S. horvatii was evaluated using the agar diffusion and broth microdilution methods. The essential oil exhibited antimicrobial activity to varying degrees against all the tested strains. The maximum activity of S. horvatii oil was observed against Gram-positive bacteria (Micrococcus luteus, Staphylococcus epidermidis, Staphylococcus aureus and Enterococcus faecalis) and against the yeast (Candida albicans). The oil exhibited moderate activity against the Gram-negative bacteria Escherichia coli and Klebsiella pneumoniae and weak activity against Pseudomonas aeruginosa. This study confirms that the essential oil of S. horvatii possesses antimicrobial activities in vitro against medically important pathogens.