Antibacterial activity of Ethiopian Lepidium sativum L. against pathogenic bacteria

Lepidium sativum is commonly known as “fetto” in Ethiopia, and a popular herbal plant which is widely used in folk medicine. The objective of this study is to investigate the potential of three different crude solvent extracts from seed of Lepidium sativum (ethanol, methanol and chloroform) against human pathogenic bacterial strains: Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC-27736), Pseudomonas aeruginosa (ATCC-27853), Staphylococcus aureus (ATCC-25923) and Shigella sonnie (ATCC-25931) using agar well diffusion assay, and the test results were compared with standard antibiotics. This study revealed that the ethanol and methanol extracts showed maximum antibacterial activity against E. coli (ATCC 25922) with zone of inhibition mean value of 22.63±0.7 mm. The methanol extract showed minimum antibacterial activity against P. aeruginosa (ATCC-27853) with zone of inhibition mean value of of 9±0.3 mm. Among the extracts, ethanol has a higher minimum inhibitory concentration (MIC) with inhibition value ranges of 6.25 to 12.5 mg/ml than other solvents extract. The results suggest that ethanolic and methanolic extracts of L. sativum could be used for treatment of infectious diseases caused by E. coli and P. aeruginosa strains. Hence, further investigation of biochemical elements of the ethanolic and methanolic extracts and understanding of the genetic mechanisms of resistance will be beneficial.    Key words: Antibacterial activity, extract, Lepidium sativum, minimum inhibitory concentration (MIC), zone of inhibition.