The progressive increase in antimicrobial resistance was the major attribute among human pathogens that has given rise to the need to investigate other sources of therapy from various sources such as medicinal plants. The aim of this study was to assess the antibacterial activity of crude extract of leaves and bark of Millettia ferruginea against human pathogenic bacteria (Staphylococcus aureus and Shigella boydii) and Candida albicans. Maceration technique was employed for extraction of the plant by using solvents of different polarity levels. Antibacterial and antifungal activities of each crude extracts were evaluated at a concentration of 100mg/ml, 200mg/ml and 300mg/ml via agar well diffusion assay. The standard drugs of 30μg/ml and 1 ml of DMSO were used as positive and negative control respectively. Minimum inhibitory concentration was also determined. The result of the study indicated that all the three solvent extracts of leaf of Millettia ferruginea did not shown antibacterial activity for test pathogens. Acetone and chloroform bark extracts showed antibacterial activity at all three concentrations. Minimum inhibitory concentration (MIC) for acetone bark extracts were 12.5mg/ml and 25mg/ml for Staphylococcus aureus and Shigella boydii respectively and also for chloroform extracts 25mg/ml and 50mg/ml for Staphylococcus aureus and Shigella boydii respectively. Ethanol bark extracts showed antibacterial activity only for Staphylococcus aureus at higher concentrations (200mg/ml and 300mg/ml) with minimum inhibitory concentration (MIC) of 200mg/ml. Acetone extract at 300mg/ml was insignificantly different from the antibiotic Gentamicine (P = 0.12). The present results concluded that out of three leaf extracts and three bark extracts, only chloroform and acetone extracts of bark have antibacterial activity against either Staphylococcus aureus or Shigellaboydii, while no any of the prepared extracts had antifungal action.
Keywords: Millettia ferruginea, MIC, in vitro natural antimicrobial assay, S. aureus, Shigella boydii