Isolation and identification of bioactive antibacterial components in leaf extracts of Vangueria spinosa (Rubiaceae)

OBJECTIVE: The column chromatographic fraction of ethyl acetate (EA1, EA2, EA3, EA4 and EA5) leaf extracts of Vangueria spinosa (V. spinosa) were screened for antibacterial activity and phytochemical analysis. METHODS: EA3 fraction was isolated and identified by column chromatography, thin layer chromatography, spectral data analysis and phytochemical screening were used for analysis. RESULTS: EA3 fraction was significantly active at 4 to 64 mg/L against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa with minimum inhibitory concentration of 1.5625 to 3.1250 mg/mL. The active fraction (EA3) revealed the presence of flavonoid with retention factor value (R(f)) of 0.39. The active antibacterial agent in the most potent fraction (EA3) was isolated and identified as flavonoid (-)-epicatechin-3-O-β-glucopyranoside by thin layer chromatography (TLC) and phytochemical screening. EA1 and EA2 show inhibitory activity at 4 to 64 mg/L against Staphylococcus aureus only where as fraction EA4 and EA5 do not shows any inhibitory activity within that range of concentration against any bacteria. CONCLUSIONS: The results support the ethnomedicinal use of leaf of V. spinosa for the treatment of bacterial diseases.