Background: Plant cells fundamentally are chemical factories containing a rich supply of therapeutically useful phytocompounds that have the potential of being developed into potent antimicrobial agents.
Aim of the study: To investigate the antibacterial activity of fractionated extracts of the ethyl acetate extract of the stem bark of Bridelia micrantha (Hochst., Baill., Euphorbiaceae).
Materials and methods: Thin-layer chromatography and column chromatography were used to purify the extracts and antimicrobial activity performed on reference and clinical strains of Staphylococcus aureus, Shigella sonnei, Salmonella Typhimurium, and Helicobacter pylori using direct and indirect bioautographic methods respectively. Furthermore, the eluted compound fractions were then assayed for minimum inhibitory concentration (MIC50) using the 96-well micro dilution technique.
Results: Better separation of phytocompounds was obtained from the non-polar Benzene/Ethanol/Ammonia (BEA) and intermediate-polar Chloroform/Ethyl acetate/Formic acid (CEF) eluents compared to the polar Ethanol/Methanol/Water (EMW). Bioautography revealed the presence of three bioactive compounds (Rf values; 0.12, 0.20, and 0.42) on the BEA plates, designated fractions 3, 7, and 8 with MIC50 values; 0.0048mg/mL to 1.25mg/mL (fraction 3), 0.0024mg/mL to 5 mg/mL (fraction 7), and 0.0024mg/mL to 2.5mg/mL (fraction 8).
Conclusion: Our findings demonstrate that ethyl acetate extract of the stem-bark of B. micrantha possess potent bioactive phytocompounds that may be developed into new antimicrobials.
Keywords: Antibacterial activity; Bridelia micrantha; euphorbiaceae; medicinal plants; minimum inhibitory concentration.