Efficacy Evaluation of Aqueous Extract of Brassica nigra seeds as Antimicrobial Agent against Selected Microorganisms: Gram-Positive Staphylococcus aureus and Gram-Negative Escherichia coli and Pseudomonas aeruginosa.

Spices are used as additives to flavor, colour or preserve food during fanciest time in Bangladesh. These are pungent or aromatic ingredients gotten from by dried seeds, fruits, roots, bark or leaves. These flavoring substances are the potential source of organic products and naturally derived compounds. These compounds show the antioxidant, antimicrobial properties. The aim of this experimental study was to see the antibacterial effect of aqueous extract isolated from seeds of Brassica nigra in vitro. This interventional study was conducted from January 2022 to December 2022 in the Department of Pharmacology and Therapeutics in collaboration with The Department of Microbiology, Mymensingh Medical College, Bangladesh. In this study, antimicrobial activities of aqueous seeds extracts of Brassica nigra were tested against S. aureus, E. coli & P. aeruginosa by using disc diffusion method and MIC determination by broth dilution method. The extract was prepared by using aqueous solvent. The tested microorganisms were also tested for their activity against a standard antibiotic Gentamicin. Aqueous Black mustard seeds (ABMSE) were used initially in eight different concentrations (25, 50, 100, 200, 400, 600, 800 and 1000μg/ml) and later in selected concentrations as needed to confirm the more precise margin of antimicrobial sensitivity of the extracts. Among different concentrations of the ABMSE, 400μg/ml and above concentrations showed inhibitory effect against aforesaid bacteria. The MICs of ABMSE were 500μg/ml, 650μg/ml and 400μg/ml against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa respectively. The MIC of Gentamicin was 1μg/ml against S. aureus, 1.5μg/ml against E. coli and 1μg/ml against P. aeruginosa. The MIC of Gentamicin was lowest in comparison to ABMSE for the test organisms. The subculture study showed the same results with that of previous experiments. The extract showed a broad spectrum of antimicrobial activities by inhibiting the growth of respective microorganism in Agar well diffusion assay. This study supports the antibacterial effect of Brassica nigra seeds. It may be helpful for future researches in area of new drug development of herbal origins.