Antibacterial Activity of Aegopodium podagraria L. Extracts and Interaction Between Extracts and Antibiotics

Antibacterial activities of aqueous, ethanol, and ethyl acetate extracts of Aegopodium podagraria L. (Apiaceae) were tested in vitro against 6 bacteria species. Antibacterial properties were determined by disk diffusion and tube dilution method. Based on the minimal inhibitory concentrations (MIC), the ethanol extract showed the highest activity (1.25-5 mg/ml). Among the tested bacteria, the most sensitive species were Enterobacter cloacae, Klebsiella pneumonia, and Pseudomonas fluorescens, while the most resistant was Staphylococcus aureus. Ethanol extract was chosen to investigate the effects of its combinations with commercial antibiotics by the checkerboard method. Results showed that the interactions between ethanol extract/streptomycin and ethanol extract/chloramphenicol were synergistic, additive, and indifferent against the tested human-pathogenic bacteria. Synergism was observed in relation to Bacillus subtilis. Synergy was confirmed at an ethanol extract concentration corresponding to 1/4 MIC and antibiotic concentrations corresponding to 1/4 MIC and lower.