In vitro antimicrobial and phytochemical properties of crude extract of stem bark of Afzelia africana (Smith)

Abstract

Afzelia africana is used in folklore remedies for the treatment of diarrhoea, gastrointestinal disorders and gonorrhoea among other ailments; hence we assessed the in vitro antimicrobial activities of this
important medicinal plant. Thirty bacterial isolates as well as four fungal isolates were tested in this study. The crude extract of the stem bark of the plant exhibited antimicrobial activities at a concentration of 25 mg/ml against twenty-one of the bacterial isolates, (i.e. 72.41% of the tested isolates) comprising both Gram positive and Gram negative strains. The zones of inhibition exhibited by the extract against the test bacterial species ranged between 13 and 22 mm. The Minimum Inhibitory Concentrations (MIC) of the extract vary between 1.56 and 12.50 mg/ml while the Minimum Bactericidal Concentration (MBC) ranged between 3.13 and 25.00 mg/ml. However, the extract lacked activity against all four tested fungal species. Phytochemical assay revealed the presence of alkaloids, tannins, flavonoids and saponins in the extract. We conclude that the stem bark of A. africana is a promising candidate as source of new antibacterial compounds.