Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 40: 2738 - 2745. Published April 14, 2011.
Antibacterial activities of seed-pod extracts of Acacia nilotica Willd to Artemia salina larvae
1Mbatchou V. Chi and 2Adoum O. Moubarak
1Department of Applied Chemistry and Biochemistry, University for Development Studies, P. O. Box 24, Navrongo, Ghana; 2Department of Chemistry, Bayero University Kano, P. M. B. 3011 Kano, Nigeria.
*Corresponding author email: mbatcham@yahoo.fr
ABSTRACT
Objectives: To evaluate the antibacterial activities of solvent partitioned fractions of the seed-pod extracts of Acacia nilotica Willd.
Methodology and results: The EtOH (ethanol) soluble extract, the CHCl3 (chloroform) phase, the distilled H2O-EtOAc (water-ethyl acetate) interphase and the EtOAc (ethyl acetate) soluble fractions of the seed-pod of Acacia nilotica Willd obtained by extraction and fractionation processes respectively, were investigated using paper disk-plate technique for growth inhibitory effect on Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa and Staphylococcus aureus. In addition, 25g of the EtOH soluble extract of the seed-pod of A. nilotica Willd was column chromatograghed using different solvents and solvent mixtures (petroleum ether, petroleum ether-CHCl3, CHCl3-EtOAc, EtOAc, EtOAc-MeOH and MeOH), and column chromatographed fractions were tested on Artemia salina Leach (brine shrimp) larvaeusing brine shrimp bioassay technique which is indicative of pesticidal, cytotoxic and other pharmacological effects. The EtOH soluble fraction of the extract inhibited the growth of Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa and Staphylococcus aureus. This extract inhibited the growth of Staphylococcus aureus at 2,000µg/ml concentration, whereas for Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris and Pseudomonas aeruginosa, it inhibited growth at 5,000µg/ml concentration. The respective growth inhibitory mean values recorded were 3±0.42mm, 5±0.27mm and 8±0.44mm for Staphylococcus aureus, 7±0.60mm and 8±0.18mm for Escherichia coli, 7±0.20mm and 8±0.05mm for Klebsiella pneumonia, 7±0.40mm and 8±0.60mm for Proteus vulgaris, and 7±0.40mm and 8±0.44mm for Pseudomonas aeruginosa. The CHCl3 soluble fraction inhibited the growth of Staphylococcus aureus at the concentrations of 5,000µg/ml and above with the minimum zone of inhibition being 6±0.5mm. The distilled H2O-EtOAc interphase soluble fraction demonstrated growth inhibitory activity on Escherichia coli at concentrations of 5,000µg /ml and above with the minimum zone of inhibition being 6±0.09mm. The EtOAc soluble fraction demonstrated growth inhibitory activity on Staphylococcus aureus only at 10,000µg/ml, both Pseudomonas aeruginosa and Klebsiella pneumoniae at 5,000µg /ml and above, and both Escherichia coli and Proteus vulgaris at all the tested concentrations. The respective growth inhibitory mean values recorded were 7±0.40mm for Staphylococcus aureus, 7±0.27mm and 8±0.20mm for Pseudomonas aeruginosa, 7±0.17mm and 8±0.44mm for Klebsiella pneumoniae, 2.1±0.20mm, 3±0.10mm, 4.5±0.20mm and 7±0.10mm for Escherichia coli, and 3±0.05mm, 4±0.10mm, 6±0.20mm and 9±0.10mm for Proteus vulgaris. The growth inhibitory effect demonstrated by the EtOH soluble extract and other solvent soluble fractions on the bacterial isolates indicated that the seed-pod of the plant contained antibacterial agents. The activity of column chromatographed fractions AN-8-7, AN-8-12 and AN-8-14 of the seed-pod on Artemia salina Leach larvae was also an indication of pesticidal, cytotoxic and Pharmacological effects, and were correlated with the traditional medicinal uses of the plant, with fraction AN-8-12 being the most active at 95 % confidence interval and LC50 value of 126 µg/ml concentration.
Conclusion and application of findings: These results supported the use of the seed-pods of Acacia nilotica Willd by cattle rearing Fulani men in Northern Nigeria to treat foot and mouth cow disease. It also revealed that the seed-pods can be used to treat diseases caused by the beta-lactamase producing bacteria used in the research which are known to be resistant to some penicillin antibiotics.
Key words: Seed-pod extracts, Acacia nilotica Willd, antibacterial effect, column chromatography, Artemia salina and cytotoxicity
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