Bioprospecting of pods of Moringa oleifera Lam. as novel antibacterial agent

Abstract

In the treatment of bacterial diseases, increasing resistance to traditional chemotherapeutics has drawn the necessity for substitute remedies. In this context, here, we evaluated the bactericidal activity of pods of Moringa oleifera Lam., an ethno medicinal plant, against eight pathogenic bacterial strains, both Gram positive (Bacillus licheniformis, B. mycoides, B. subtilis and Staphylococcus aureus) and Gram negative (Escherichia coli, Pseudomonas aeruginosa, P. fluorescens and P. putida). Different organic solvent extracts, like ethyl acetate, acetone and alcohol, of pods of M. oleifera were examined for bactericidal activity against test microorganisms. Minimum inhibitory concentration, chromatographic analyses along with infrared spectroscopy, gas chromatography-mass spectroscopy and nuclear magnetic resonance spectroscopy was carried out for chemical characterization of active ingredient responsible for antibacterial activity. Both the Gram positive and Gram negative organisms showed variable sensitivity to different solvent extracts of M. oleifera pods. Ethyl acetate extracts showed maximum antibacterial activity with MIC value ranging from 1.30 to 4.10 mg/mL. IR analysis provided preliminary information about the amines, amides, aromatics and sulphur containing compounds of the active ingredient. GC-MS and NMR analyses indicated the presence of principal bioactive antibacterial compound 2-(benzoylsulfanyl)-1,3- thiazol,4-yl, benzoate with molecular formula C17H11NO3S2 from ethyl acetate extract of M. oleifera pods. The study concludes that the compound 2-(benzoylsulfanyl)-1,3-thiazol,4-yl, benzoate from ethyl acetate extract of pods of M. oleifera possess the antibacterial activity against the tested strains.