Phytochemical and antimicrobial screening of Globimetula oreophila (Oliv) van Tiegh and Phragmanthera capitata (Spreng) Balle

Abstract

Background: Medicinal plants will continue to be relevant in the production of lead compounds that can be utilized for its antibacterial activity directly or through chemical modification (s). Aims: The present study is conducted to evaluate the antibacterial activity vis‑a‑vis phytochemical constituents of Globimetula oreophila and Phragmanthera capitata. Materials and Methods: Cup plate agar diffusion assay was used to determine the minimum inhibitory concentrations (MIC) of the extracts of both plants against Escherichia coli, Klebsiella spp., Shigella spp., Salmonella typhi, Staphylococcus aureus and Pseudomonas aeruginosa by plotting the diameters of zones of inhibition against the logarithm of concentrations and the straight line graph so generated extrapolated to the value equivalent to the diameter of the cork‑borer. The antilog of the corresponding value of concentration was taken as the MIC value. Statistical Analysis: All the values of the results of cup plate diffusion assay were expressed as means of two replicates ± standard deviation. Results: Preliminary phytochemical screening reveals the presence of saponin, tannins, alkaloids, anthraquinones and flavonoid in both plants. Antibacterial screening of both plants showed that both of them were active against all clinical bacterial isolates tested with P. capitata having a higher activity than G. oreophila on most of the isolates. The ability of both plants to inhibit the growth of S. typhi is a major breakthrough in the control of incidence of typhoid fever notwithstanding the reports of resistance to existing antibiotics. Conclusion: It therefore follows that the importance of both plants in the management and control of infections with which all the bacterial isolates used for this study were associated cannot be underestimated. Key words: Cup plate agar diffusion, Globimetula oreophila, minimum inhibitory concentrations, Phragmanthera capitata, Salmonella typhi