Antibacterial activity of ethanolic and aqueous extracts of four medicinal plants on the in vitro growth of Escherichia coli and Staphylococcus aureus

Abstract

Summary Evaluation of antibacterial activity of four medicinal plants used in the treatment of diarrheal diseases. To determine the antibacterial activity of total aqueous and ethanolic extracts of different plants, agar diffusion (Muller-Hinton) and broth macrodilution (Muller-Hinton) methods( DMHB) were used tested on Staphylococcus  aureus ATCC 25923 and Escherichia coli ATCC 25922 and two clinical strains Escherichia coli 18170 and Staphylococcus aureus 1315. The diameters of inhibition and minimum inhibitory concentrations were determined. The studies carried out by the method of agar diffusion method and the double dilution revealed that extracts of Terminalia mantaly H. Perrier (Combretaceae) has an inhibitory activity on all tested strains. The inhibitory diameters vary between 7.66 mm and 35mm. The minimum inhibitory concentrations (MIC) of the extracts ranged from 0.78 mg /mL and 2.5 mg /mL. The ethanolic extracts inhibit the growth of bacteria at lower concentrations than the aqueous extracts. Terminalia mantaly has a stronger antibacterial activity and thus can be useful in the search for new molecules to fight against bacterial resistance.  Keywords: antibacterial activity, inhibition diameters, minimum inhibitory concentration, Terminalia mantaly