Abstract:
There are many reports about usage medicinal plants and their potential as possible therapeutic agent against human pathogens. The aim of this study was to determine the antibacterial activity of different concentrations of petroleum ether, methanol and aqueous extracts of the medicinal plant Nigella sativa (seeds) using disc diffusion method on reference standard and selected pathogenic isolates of bacteria.
The study was conducted in Khartoum state, Sudan, during the period from May to November 2018. Fife Reference strain and forty isolated pathogenic bacteria were tested for their sensitivity to Nigella sativa extracts. The Reference strain includes P. aeruginosa ATCC27853 K. pneumonia ATCC 53657, E. coli ATCC 25922, B. subtilis NCTC8236. While the selected pathogenic strain included Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Proteus species, staphylococcus epidermidis, bacillus cerus and Pseudomonas aeruginosa.
Petroleum ether and methanol extract of Nigella sativa showed pronounced dose dependant antibacterial activity against the Reference strains and clinical isolates of Staphylococcus aureus, staphylococcus epidermidis, B. subtilis NCTC8236, bacillus cerus, E. coli ATCC 25922 and clinical isolates of Escherichia coli. But showed no activity against Klebsiella pneumoniae ATCC 53657 and Proteus species. Petroleum ether extract was partially active against the reference strain of Pseudomonas aeruginosa ATCC27853, while the isolated pathogenic strains of Pseudomonas aeruginosa were non sensitive to the extract.
The aqueous extract showed no activity to all tested Grams negative organism it just showed activity against Staphylococcus aureus, staphylococcus epidermidis, bacillus subtilis NCTC8236 and bacillus cerus.
The study concluded that the greatest activity of Nigella sativa extract were against Gram positive bacteria.
Further studies using large sample size and advance techniques are required to validate the results of this study.
