In Vitro antibacterial activity of rumex nervosus, plantago lanceolata, solanum incanum and lepidium sativum against selected bacterial pathogens of human and animals

Medicinal plants are used as a primary means of tackling different ailments especially in developing countries. In the present study, the leaves of Rumex nervosus, Plantago lanceolata, Lepidium sativum and Solanum incanum were collected and extracted by maceration method using 70% methanol. The extracts were concentrated and the yields recorded. Antibacterial effects of the extracts were tested on selected bacteria such as Streptococcus, S. aureus, L. monocytogenes, E. coli, and Salmonella which were obtained from Haramaya University, Veterinary Microbiology Laboratory. Preliminary screening test for the extract was made using agar disc diffusion method and subsequently the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by agar dilution assay based on the zone of bacterial growth inhibition. The finding indicated that Rumex nervosus showed have the highest zone of inhibition (20mm) against the genus Salmonella followed by Plantago lanceolata with the zone of inhibition (16mm) against L. monocytogenes. On the other hand, Lepidium sativum and Solanum incanum did not have any antibacterial activity against all the cultured bacteria. The minimum inhibitory concentration and the minimum bactericidal concentration of Rumex nervosus against S. aureus were 1.56x103μg/ml and that of Plantago lanceolata against L. monocytogenes were 6.25 x103μg/ml and 1.25 x 104μg/ml, respectively. From the findings it can be concluded that Rumex nervosus and Plantago lanceolata have shown to be a better antibacterial activity against selected bacterial pathogens, while leave extracts of other medicinal plants do not have any effect. Fractionated components of the plants might show better effect which needs further investigation using different solvent and standard medium.Keywords: Agar disc diffusion, Antibacterial activity, Rumex nervosus, Plantago lanceolata, Solanum incanum, Lepidium sativu