Medicinal plants are targeted in the search for new antimicrobial agents.Nowadays, there is an alarmingly increasing antimicrobial resistance to available agents with a very slow development of new antimicrobials.It is, therefore, necessary to extensively search for new agents based on the traditional use of herbal medicines as potential source.The antibacterial activity of 80% methanol extracts of the leaves of Verbena officinalis (Vo-80ME), Myrtus communis (Mc-80ME), and Melilotus elegans (Me-80ME) was tested against 6 bacterial isolates using agar well diffusion technique.In each extract, 3 concentrations of 10, 20, and 40 mg/well were tested for each bacterium.
The minimum inhibitory concentration (MIC) and minimum bactericidal Model Kits concentration (MBC) were also determined.Vo-80ME and Mc-80ME exhibited promising antibacterial activity against Staphylococcus aureus with the highest zone of inhibition being 18.67 and 26.16 mm, respectively at concentration of 40 mg/well.Regarding gram-negative bacteria, Vo-80ME exhibited an appreciable activity against Escherichia coli and Salmonella typhi.
Mc-80ME displayed remarkable activity against all isolates including Pseudomonas aeruginosa with the maximum zone of inhibition being 22.83 mm.Me-80ME exhibited better antibacterial activity against E coli, but its secondary metabolites had little or no activity against other gram-negative isolates.The MIC values of Vo-80ME ranged from 0.16 to 4.
00 mg/mL.The lowest MIC was observed in Mc-80ME, with the value being 0.032 mg/mL.Mc-80ME had bactericidal activity against all tested bacterial isolates.Mc-80ME showed remarkable zone of inhibitions in all tested bacterial isolates.
Besides, Vo-80ME showed good antibacterial activity against S aureus , E coli , and S typhi.Conversely, Me-80ME has Stems shown good activity against E coli only.Generally, M communis L and V officinalis have good MIC and MBC results.