<i>In vitro</i> antibacterial activity of crude methanol extracts of various parts of <i>Parthenium hysterophorus</i> against pathogenic bacterial strains

Abstract

Parthenium hysterophorus is an aggressive and exotic weed plant traditionally reported to be used as remedy for various diseases. In the present study in vitro antibacterial activities of P. hysterophorus leaf, flower, bark and root crude methanol extracts were evaluated against five reference strains of pathogenic bacterial species. The P. hysterophorus was collected from Haramaya University campus from December 2015 to April 2016. Each leaf, flower, bark and root of P. hysterophorus was separately collected, dried, grinded and crude methanol soluble was extracted. The extracts were tested against Shigella flexneri, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus agalactiae and Escherichia coli using standard agar disc diffusion assay at three different concentrations (1000mg/ml, 500mg/ml and 250 mg/ml) from each parts. Standard antibiotic (Chloramphenicol 30μg/disc) was used as positive control and DMSO (0.5%) was used as negative control. Among the P. hysterophorus parts tested: leaf, flower, bark and root showed promising inhibitory activities against the tested bacterial strains at all concentration except bark extract at 250mg/ml, root 500mg/ml, root 250mg/ml did not show antibacterial activity against Streptococcus agalactiae, Staphylococcus aureus and Streptococcus agalactiae, respectively. The crude extract from all parts of the plant showed a concentration dependent mean zone of inhibition on all the tested bacterial strains. Methanol crude extract of P. hysterophorus parts were active against the tested bacterial strains and promising for refined medicinal drug source. In vivo toxicity and efficacy test should be done to validate the importance of this plant for future development of lead compounds.

Keywords: Antibacterial activity; Bacterial pathogen; Concentration; Parthenium hysterophorus