The Comparative Study of Phytochemical Constituents and Antibacterial Activities of Methanolic Extracts of the Leaf and Stem Bark of Anogeissus leiocarpus (DC.) Guill & Perr

Abstract

This study was aimed at investigating and comparing the phytochemical constituents and antibacterial activities of methanolic extracts of the leaf and stem bark of Anogeissus leiocarpus plant against Eschericia coli, Klebsiella pnuemoniae, Pseudomonas aeruginosa, Staphylococcus aureus and Proteous mirabilis isolated from patients suffering from urinary tract infection. 500 g of each of the pulverised plant parts were used for extraction using a Soxhlet extractor. Standard chemical procedures were used for qualitative and quantitative phytoconstituents present in the plant extracts. The agar-well diffusion method and the tube dilution method were adopted to determine the antibacterial activity and minimum inhibitory concentration of the extracts, respectively. Phytochemical screening of the crude extracts of the leaf and stem bark revealed that both extracts contain alkaloids, flavonoids, saponins, tannins, phenols, and steroids, whereas only the stem bark consisted of cardiac glycosides. The result shows that the stem bark extract was more effective in inhibiting all five tested pathogens with zones of inhibition ranging between 10.88±0.56 and 26.24±0.00 as compared to the leaf extract 9.00±0.65 and 16.00±1.50, while the standard antibiotic (nitrofurantoin) exhibited greater activity with zones of inhibition ranging between 24.00±0.25 and 32.00±0.52. The phenolic and flavonoids contents were found to be higher in the stem bark (122.72±0.00 and 72.16±0.05) than the leaf (89.25±0.05 and 48.28±0.00, respectively). The MIC and MBC ranged between 2.5–25 mg/ml and 5–25 mg/ml for the leaf, whereas 0.625–10 mg/ml and 2.5–20 mg/ml for the stem bark. These results support the use of stem bark in herbal medicines for the treatment of patients with urinary tract infections.