World Journal of
Pharmaceutical and Life Sciences

ANTIBACTERIAL ACTIVITY OF THE AQUEOUS AND METHANOLIC SEED EXTRACTS OF NIGELLA SATIVA LINN. (RUNUNCULACEAE) IN MAIDUGURI

Sulayman Tunde Balogun, Amina Umar Ibrahim, Ayodele Oluwasoji Akanmu, Olufunke Adebola Sodipo*, Isa Gulani

ABSTRACT

The present study examined the antibacterial activity of the aqueous and methanolic seed extracts of Nigella sativa Linn. against some Gram negative (Escherichia coli, Salmonella typhi, Klebsiella pneumoniae and Pseudomonas aeruginosa) and Gram positive (Staphylococcus aureus, Streptococcus pyogenes, Bacilus subtilis and Corynbacterium spp.) bacteria. The dried seed powder was subjected to reflux method of extraction using distilled water and methanol for the aqueous and methanolic extracts, respectively. The seed extracts were further subjected to phytochemical screening using a standard method and in vitro antibacterial sensitivity tests using the disc diffusion method. Zones of inhibition, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. The percentage yields were 18.24 and 16.03% (w/w) for aqueous and methanolic extracts, respectively. The phytochemical screening revealed presence of carbohydrates, terpenoids, cardiac glycosides, saponin glycosides, tannins, alkaloids and flavonoids in both the aqueous and methaolic seed extracts. The results of the sensitivity test showed that the aqueous extract was active against only S. pyogenes at concentrations of 200 and 300 mg/ml while methanolic extract inhibited the growth of S. aureus, B. subtilis, Corynbacterium spp., S. typhi and P. aeruginosa. In addition, the methanolic extract was most active at the highest concentration of 300 mg/ml against S. aureus. The results of the MIC showed that P. aeruginosa had the MIC of 50 mg/ml, S. aureus and C. specie had the MIC value of 25 mg/ml while B. subtilis and S. typhi had the MIC value of 12.5 mg/ml. The results of the MBC for P. aeruginosa, S. aureus, C. specie, S. typhi and B. subtilis were 100, 50, 50, 25 and 12.5 mg/ml, respectively. In conclusion, the seed extracts are rich in phytochemicals and the methanolic extract demonstrated more antibacterial activity than the aqueous extract. These findings may provide justification for the traditional uses of the plant.

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