Essential oil variation in the populations of Artemisia spicigera from northwest of Iran: chemical composition and antibacterial activity.

Artemisia spicigera C. Koch (Asteraceae) is a perennial shrubby herb and is generally distributed in Armenia, Iran, and Middle Anatolia. This species traditionally has been used in medicines. The aim of this research is to study the chemical composition and antibacterial activity of essential oils from Artemisia spicigera populations in northwest of Iran. The essential oil of A. spicigera was obtained by hydrodistillation from eight populations collected from different regions of East Azerbaijan and West Azerbaijan provinces (Iran) and analyzed by gas chromatography-mass spectrometry (GC-MS). The antibacterial activity of the oils was investigated against four Gram-positive and four Gram-negative bacteria using MIC determinations and the agar-gel diffusion method. Fourteen compounds were identified as the main components of the essential oils and the most abundant constituents are 1,8-cineole, camphor, α-thujone, camphene, β-thujone and p-cymene. Essential oil of population No. 1 showed the highest activity against Escherichia coli, Enterobacter aerogenes, Serratia marcescens and Staphylococcus aureus but the highest activity against St. saprophyticus, Bacillus megaterium, and B. cereus was found with population No. 6 and for Citrobacter amalonaficus with population No. 5. MIC values of essential oils ranged from 6 µg/mL against Bacillus megaterium to 12 µg/mL against Citrobacter amalonaficus. This study demonstrates the occurrence of 1,8-cineole/camphor/camphene chemotype of A. spicigera but there is also significant chemical variation between the studied populations. The findings showed the studied oils have good antibacterial activity, and thus potential to be used as natural health products.