Antioxidant activity and antimicrobial effect of tarragon (Artemisia dracunculus) extract and chemical composition of its essential oil

The aim of this study was to determine the chemical composition, antioxidant potential and phytochemical analysis of Artemisia dracunculusas as well as its antibacterial and antifungal effects (individually or in combination with Coriandrum sativum and Plantago major) “in vitro”. Total phenolic content, total flavonoid content and anthocyanin content were determined through spectrophotometric methods. Antioxidant potential was determined calorimetrically for 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity. The disk diffusion method and hole-plate diffusion method were used to assess the diameter of the inhibition zone. The pour plate method was adopted to determine the susceptibility of the pathogenic strains against Artemisia dracunculusas extract. The broth microdilution and agar dilution methods were employed to measure the minimum inhibitory concentration. The minimum bactericidal/fungicidal concentration was measured using the wells in which no turbidity/color change was observed. The fractional inhibitory concentration index (FICI) was also determined for the extracts. The chemical composition of Artemisia dracunculusas essential oil was analyzed by gas chromatography and gas chromatography/mass spectrometry. The results showed that IC50 of A. dracunculus was 65.4 μg/ml, Total phenolic content was equal to 24.10 mg GAE/g, total flavonoid content was 20 mg QE/g. The major components included p-Allylanisole (84.00%), Ocimene (E)-beta (7.46%), Ocimene (Z)-beta (6.24%) and Limonene (1.42%), respectively. The extract of A. dracunculus exhibited strong antimicrobial activity against fungi with an average inhibition zone of 14.70 mm. All bacteria (except Streptococcus pyogenes and Staphylococcu aureus) were more resistant than Candida albicans. Regarding the checkerboard data, 10 FICIs (≤0.5) showed the synergistic effect, whereas eight FICIs (>0.5 to 1) indicated the additive effect.