ANTIBACTERIAL ACTIVITY OF STEM BARK AND ROOT OF INDIAN ZANTHOXYLUM NITIDUM

The in vitro antibacterial activity of aqueous and ethanol extracts from the stem bark and root of Zanthoxylum nitidum (Roxb.) DC (Rutaceae), growing in north-east India was evaluated against five Gram-positive bacteria including Staphylococcus aureus, Streptococcus faecalis, Bacillus cereus, Sarcina lutea, Bacillus subtilis and two Gram-negative bacteria, Klebsiella pneumoniae, and Escherichia coli; using disk diffusion method followed by determination of minimum inhibitory concentrations (MIC) by broth dilution method, against sensitive bacteria. All extracts, at higher concentrations showed varying degrees of inhibitory activity against all bacteria; except the aqueous extract of the stem bark, which was inactive against S. lutea and B. subtilis. The highest activity was exhibited by the ethanol extract of root against B. cereus, while the lowest activity was exhibited by aqueous extract of stem bark against K. pneumoniae; in the highest (40 mg/ml) concentration. The ethanol extract of root was the most active, showing maximum concentration dependent antibacterial effects and the aqueous extract of stem bark was the least active. Root extracts exhibited higher antibacterial effects than stem bark extracts. Gram-positive bacteria were more sensitive to the extracts, except aqueous extract of stem bark.