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.