Bita Arabestani
Laleh Babaeekhou
Maryam Ghane

Background: This study investigated the antibacterial properties of four types of tarragon (Artemisia dracunculus) extracts against two caries contributing bacteria, namely, Streptococcus mutans and Streptococcus sobrinus. Methods: The extracts of A. dracunculus were prepared using n-hexane, ethyl acetate, methanol, and water solvents. In addition, the diameter of inhibition zones, minimum inhibitory concentrations (MICs), and minimum bactericidal concentrations (MBCs) were determined, and finally, MTT (tetrazolium-based colorimetric assay) was used to analyze the cytotoxic effects of the extracts. Results: The well-diffusion method showed the antibacterial property of four tested extracts against bacteria. Methanol and water extracts made the highest inhibition zone diameters (P<۰.۰۰۱). This was true for both tested bacteria. The mIC of the methanol, water, n-hexane, and ethyl acetate extracts were ۰.۷۸, ۱.۵, ۳.۱, and ۱.۵ mg/mL, as well as ۰.۷۸, ۰.۷۸, ۱.۵, and ۱.۵ mg/mL against S. mutans and S. sobrinus, respectively. The half-maximal inhibitory concentration (IC۵۰) values for methanolic, aqueous, ethyl acetate, and n-hexane extracts were ۰.۷۸, ۰.۷۸, ۱.۵۶, and ۳.۱۲ mg/mL, respectively. Conclusions: The results provided a rational reason for the traditional use of A. dracunculus extracts against anti-caries-related bacteria. The methanolic extract demonstrated better activity, thus methanol can probably extract a wider range of plant compounds with antibacterial effects.