Activity-directed fractionation and isolation of four antibacterial compounds from Abrus precatorius L. roots

Root extracts of the plant Abrus precatorius L. was tested for antibacterial activity. Various solvent fractions exhibited inhibitory activity against 13 gram-positive and gram-negative bacteria. Root extracts were analyzed by thin layer chromatography. The antibacterial activity was localized to specific chromatophores in the chloroform fraction through a bioautography assay. It was found localized to 4 chromatophores out of 7. The chromatophores were isolated from the TLC plates and rechecked for activity against Staphylococcus aureus A, using a disc diffusion assay. Among the four active principles isolated, AP 3 (Rf 0.87) exhibited maximum activity, i.e., 56% inhibition of growth of S. aureus A, in disc diffusion assay compared to the standard antibiotic Ampicillin. Results of this study suggest that chloroform extractable phytochemicals in A. precatorius L. may yield promising molecules with antibiotic activity.