Antifungal and antibacterial activities of different extracts of Harungana madagascariensis stem bark

Abstract

The antifungal and antibacterial effects of the stem bark extracts of Harungana madagascariensis Lam. ex Poir. (Clusiaceae) were examined against nine microbial pathogens causing infections in both man and animals. Hexane (H), dichloromethane (D), chloroform (C), ethyl acetate (E), acetone (A), methanol (M), and water (W) extracts were tested in vitro through bioautography and minimum inhibitory concentrations (MIC) determination using the serial micro-dilution assays. Bioautographic results revealed the presence of eight different spots. Extract A exhibited the lowest MIC of 0.04 mg/mL against Microsporum canis, while water extract (W) and methanol (M) showed the highest MIC of 2.5 mg/mL against at least one of the tested fungi when compared to amphotericin B with 0.0625–1 g/mL. Sporotrichum schenckii was the most susceptible fungal pathogen with average MIC of 0.06 mg/mL, while the acetone extract (A) was the most active against three fungal organisms when compared with other extracts. Similarly, extracts D, C, E and A exhibited very high activity with low MIC values of 0.156–0.62 mg/mL, while M and W gave the highest values of 0.31–2.5 mg/mL on bacterial pathogens as compared to gentamicin (0.02–0.62 8 g/mL). The dichloromethane extract is the most active against bacteria with average MIC of 0.19 mg/mL, while Staphylococcus aureus is the most sensitive organism; that shows susceptibility at an average MIC of 0.34 mg/mL. These results provide promising information for the potential use of the crude extracts from the stem-bark of H. madagascariensis in the treatment of bacterial and fungal infections similar to what was obtained in the leaves.

Keywords::

• Antimicrobial activity
• crude extracts
• Harungana madagascariensis
• medicinal plants
• stem bark

Declaration of interest: The authors are grateful for the financial support given through the South African National Research Foundation. This work was also supported by the Obafemi Awolowo University, Ile-Ife, Nigeria. The authors alone are responsible for the content and writing of the paper.