Evaluation of antibacterial potential of crude extract of Moringa oleifera seed on orthopaedics wound isolates and characterization of phenylmethanamine and benzyl isothiocyanate derivatives

Abstract

The antibacterial activity of crude aqueous and methanolic extracts of Moringa oleifera seed on some orthopaedic wounds isolates which include Klebsiella pneumoniae, Proteus vulgaris, Providencia stuartii, Escherichia coli, Streptococcus sp., Pseudomonas fluorescens, Acinetobacter baumannii, Burkholderia cepacia, Yersinia enterocolitica, Proteus mirabilis, Serratia rubidae, Salmonella pullorum and Klebsiella oxycota was investigated. Both the crude aqueous and methanolic extracts of the seed demonstrated an appreciable inhibitory effects on the isolates with zone of growth inhibition ranging from 15 to 30.5 mm with aqueous extract and 9 to 20 mm with methanolic extract. Both extracts compared favourably with the reference standard antibiotics used. Minimum inhibitory concentration of the seed ranged from 0.875 to 5.0 μg mL -1 in aqueous extract and 0.875 to 2.5 μg mL -1 in methanolic extract. Phytochemical investigation of the methanolic extract of the seed led to the isolation and identification of new benzyl isothiocyanate and phenylmethanamine derivatives named 4-(β-D-glucopyranosyl-1-→4-α-L-rhamnopyranosyloxyl)-benzyl isothiocyanate (4) and 4-O-α-L-rhamnopyranosyloxy-N-glucopyranosyl-1-→2-fructopyranosyloxy phenylmethanamine (5) along with three known compounds, 4-hydroxyphenyl acetic acid (1), 0-methyl-4-(4'-0-acetyl-α-L-rhamnosyloxy) benzyl thiocarbamate (2) and 4-(α-L-rhamnopyranosyloxyl)-benzyl isothiocyanate (3). The structures were elucidated by extensive spectroscopic analyses which include Infra Red, Ultra Violet, Mass Spectrophotometer, ID and 2D Nuclear Magnetic Resonance spectra as well as by comparison with literature data. Both the crude aqueous and methanolic extracts displayed broad spectrum of activity as they inhibited both the Gram negative and Gram positive bacteria tested. © 2012 Academic Journals Inc.