RESUMO
OBJECTIVE: Aqueous extracts of four medicinal plants including Ferula gummosa, Echinophora orientalis, Nasturtium microphyllum and Verbascum thapsus were used to determine their antibacterial activities and minimum inhibitory concentration (MIC). The aim of this study was to assess antibacterial activity of extracts of four medicinal plants against a Gram-positive and a Gram-negative bacteria (Staphylococcus aureus PTCC1431, and Escherichia coli HP101BA 7601c). METHODS: Radial diffusion assay was used to assess the antibacterial activity of extracted samples. Haemolysis assay was also used to examine their nontoxic effects on human red blood cells (RBCs). RESULTS: This study showed that all the mentioned plants have satisfactory antibacterial effects against both Gram-positive and Gram-negative bacteria. Minimum inhibitory concentration values of these samples were less than 750 µg/mL. In addition, no significant haemolytic activity was observed at their MIC values. CONCLUSION: The results of this study showed that all these studied plants have good potential for further studies for drug discovery.