The antibacterial effect of two medicinal plants Inula viscosa, Anacyclus valentinus (Asteraceae) and their synergistic interaction with antibiotic drugs

Abstract

With the emergence of multidrug-resistant organisms, combining medicinal plants with synthetic medicines against resistant bacteria becomes necessary. In this study, Synergism between plants extracts (methanolic extract, essential oils) of Inula viscosa and Anacyclus valentinus and two commonly used antibiotics: gentamycin and oxacillin were investigated on three bacterian strains Escherichia. coli, Bacillus subtilis and Staphylococcus aureus. In the first time, the antibacterial effect of extracts alone was tested against 7 strains by disc diffusion and microdilution methods. The minimum inhibitory concentrations of methanolic extracts ranged between 6.25 and 50mg/ml while that of the essential oils varied between 12.5 and 100μL/mL. The inhibitory concentrations of antibiotics varied between 125 and 31.25 μg/ml. Interactions extracts /antibiotics and extracts/extracts were determined by disc diffusion agar and by checkboard. The results show that the synergistic effect of combinations plant extracts/antibiotics was more important than extracts/extracts.

Keywords: antibiotic resistant; Inula viscosa; Anacyclus valentinus; synergy