<i>In-vitro</i> effects of aqueous and ethanolic extracts of <i>Parkia biglobossa</i> (Jacq.) Benth on selected microorganisms

Abstract

The in-vitro effects of aqueous and ethanol extracts of Parkia biglobosa (Jacq.) R.Br. ex G.Don synonymous to Parkia africana (common name: African locust bean) were investigated against  Staphylococcus aureus, Pseudomonas aeruginosa, Aspergillus niger, Microsporum gypseum, Aspergillus fumigatus, Microsporum audoni, and Aspergillus flavus. Staphylococcus aureus growth was inhibited by different concentrations of aqueous and ethanol infusion extracts with a Minimum Inhibitory Concentration (MIC) range of 3.125- 200mg/ml. All target fungal species except Microsporum gypseum were unaffected by the extracts and had the lowest MIC range of 12.2 – 50 mg/ml. Results further showed that the unfiltered ethanol extract of the stem had the best zone of inhibition (31 mm) against Staphylococcus aureus while the unfiltered aqueous extract of the root had the least zone of inhibition value of 5 mm. Observed inhibitory activity of the extracts is directly proportional to increase concentration in gradient. Phytochemical analyses revealed the presence of flavonoid in all the extracts while terpenoids and saponins were limited to stem and root extracts respectively. Effective performances of filtered and unfiltered extracts of both the stem and the roots against target microbes are not markedly different from each other. This alludes to the relatively heavy presence of flavonoids, tannins and terpenoids observed in
the extracts. The result obtained from this study further corroborates the antimicrobial qualities of P. biglobosa and recognizes it as an accessible plant resource for experimentations that focus on tackling the emergence of resistant pathogenic microbes of plants, animals and humans.

Keywords: antimicrobial, clinical pathogens, phytochemicals, locust bean, infusion, extraction.