Evaluation of the antimicrobial activities of leaf extracts from three Onosma species

Introduction and Objectives: Onosma L. species belonging to the Boraginaceae family are widely used as a folk medicine to treat skin burns and wound healing. In this context, the n-hexane-dichloromethane, ethyl acetate and methanol extracts from aerial parts of three Onosma L. species (O. dichroantum boiss., O. sericea Willd. and O. elwendicum Wettst.) were screened for potential antimicrobial activity against medically important bacterial strains including Escherichia coli and Staphylococcus. aureusMaterial and Methods: For antimicrobial activity assay, well-diffusion method was used according to standard protocols. After 24 hours of incubation, antibacterial activity was expressed as inhibition zone diameters (mm) produced by the plant extracts. An inhibition zone of 10 mm was arbitrarily chosen as representative of bacterial susceptibility to the Extracts. Results: The results showed that ethyl acetate extracts of the three Onosma species; and methanol extracts of O. dichroantum and O. sericea exhibited significant activity against E. coli and S. aureus with inhibition zone diameter > 20 mm. The highest antibacterial activity was observed at concentration of 100mg/ml for the ethyl acetate extract of O. sericea. The n-hexane-dichloromethane extracts of the three Onosma species did not show any significant antimicrobial activity. Conclusion: These primary results confirm the possible antibacterial potential of the aerial parts extracts of the three Onosma L. species. Further studies are needed to evaluate their therapeutic potential during infectious diseases.

کلیدواژه ها:

Antimicrobial ، leaf extracts ، Onosma