Antibacterial Activity of Rhamnus prinoides extracts against Staphylococcus aureus and Escherichia coli

Abstract Medicinal plants offer a major and accessible source of health care to people living in developing countries. Increasing in resistant microbial infections intensified the search for new, safer, and more efficacious agents to combat serious microbial infections. Acanthus sennii is one of the medicinal plants used traditionally for treatment of different infectious diseases in Ethiopian. Therefore, this research was carried out to evaluate antibacterial activity of Acanthus sennii against pathogenic bacteria. The antimicrobial activity tests of the plant extracts against pathogenic bacteria were carried out by the agar well diffusion method. Broth dilution and streak plate method were used to determine MIC and MBC of extracts respectively. The results revealed that ethanol extracts of leaves showed the highest antibacterial activity against standard strains of S.aureus with inhibition zone of 14±0.58mm and 17±0.67mm at 50mg/ml and at 25mg/ml respectively. Ethanol extracts of buds showed the highest antibacterial activity against standard strains of S.aureus with inhibition zone of 25.67±0.67mm at 100mg/ml. The lowest mean MIC value (2.6±0.52 mg/ml) was recorded with ethanol extract of leaves against standard strains and clinical isolates of S. aureus. The lowest mean MBC value (4.2±1.04 mg/ml) was recorded with ethanol extract of leaves against standard strains of S. aureu. Acanthus sennii could be a good candidate in the search for new antibacterial agents from natural products against bacterial pathogens. Therefore, further studies are needed to study their toxicology and isolate the bio- active components from this plant. Key words: Acanthus sennii, Antibacterial activity, MIC, MBC, pathogenic bacteria