Background: Medicinal plants have been considered a good source for finding new pharmaceutical chemicals, and identificationof chemical composition is the first step towards uncovering the nature of bioactive compounds. Objectives: The aim of this study was to analyze the composition of the essential oil of Ballota nigra subsp. kurdica from Iran for the first time and to test its in vitro antibacterial activity against some bacteria. Methods: The flowers of Ballota nigra subsp. kurdicawere subjected to a Clevenger extractor for essential oil extraction, and gas chromatographymass spectrometry analysis was performed for its analysis. Staphylococcus aureus, Escherichia coli, Enterococcus faecalis,Bacillus subtilis, Klebsiella pneumonia and Pseudomonas aeruginosa bacteria were used to test antibacterial activity of the essential oilusing the disk diffusion method. Results: GC-MS analysis detected 22 components in the extracted essential oil which constitutedmore than 98% of total essential oil.The main compounds of the oil were caryophyllene oxide (39.43%), trans-caryophyllene (24.88%), germacrene D (7.64%), 1-undecene (4.20%), isoaromadendrene epoxide (3.25%), and tridecane-1 (2.81%). The essential oil showed moderate to high antimicrobial activity against all tested strains. Conclusions: The data of this study suggests that the essential oil of B. nigra subsp. kurdica could be considered a natural antimicrobial agent to preserve food and treat infections in the near future.
