Phytochcmical and antimicrobial activities of the wild mango Irvingia gabonensis extracts and fractions

Abstract

Crude methanol extracts obtained from the leaf, stem bark and root of the wild mango, Irvingia gabonensis, were screened for antimicrobial properties by agar well diffusion method at three different concentrations (100mg/ml, 50 mg/ml and 25 mg/ml) against six human pathogenic microorganisms consisting of four bacteria and two fungi. The hexane, chloroform, ethyl acetate and methanol fractions of the leaf and root methanol extracts were also subjected to the same assay at concentrations of 100 mg/ml - 5mg/ml. Gentamicin and Tioconazole were used as positive and methanol as negative controls. Significant inhibitory activities were exhibited by the leaf and root extracts. The crude methanol extract of the root displayed the highest activity at a concentration of 100 mg/ml. It had a diameter of zone of inhibition of 19.7 mm while the reference drug had 19.3mm on Pseudomonas aeruginosa, the most sensitive bacteria. The fungi used in this study were also very sensitive to the leaf extract. All the active extracts and fractions exhibited concentration-dependent activities against all the test organisms. Diameter of zones of inhibition ranges from 10.0-30.0 mm. The stem bark was inactive against all the studied organisms. The most active fraction was the ethyl acetate soluble fraction of the leaf which showed a comparable antimicrobial activity against the organisms at concentrations 1OOmg/ml and 50mg/ml comparable to the reference standard drug Gentamicin and Tioconazole. The ethyl acetate soluble fractions of leaf and root were found to show the highest activity. At a concentration of 5mg/ml, the root ethyl acetate fraction inhibited the growth of all the bacteria tested. The phytochemical screening of the plant materials revealed the presence of tannins, saponins, alkaloids and anthraquinones and the absence of cardiac glycosides. Thin layer chromatography indicated the presence of phenolic compounds.