Antibacterial activity and phytochemical screening of leaf and bark extracts of Vitex negundo l. from similipal biosphere reserve, Orissa

The antimicrobial activity and phytochemicals of the leaves and bark of Vitex negundo L. was evaluated against three Gram-positive bacteria viz. Staphylococcus epidermidis, Bacillus subtilis, Staphylococcus aureus and five Gram-negative bacteria viz. Escherchia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Vibrio cholerae and Vibrio alginolyteus. Both polar and nonpolar extracts viz. petroleum ether, chloroform, ethanol, methanol and aqueous extracts were prepared and studied for antibacterial activity using disc diffusion, agar cup and broth dilution methods. Results showed promising antibacterial activity of all the extracts of both leaf and bark against E. coli, followed by S. aureus. Ethanol and methanol extracts of the leaf showed inhibition activity against both Gram-positive and Gram-negative bacteria where as petroleum ether and chloroform extracts of bark had better antibacterial activity against Gram-positive bacteria. MIC showed that 5% of the extracts were active in a concentration of 0.312 mg/ml; 27.5% in a concentration of 0.625 mg/ml and 88.75% in a concentration of 1.25 mg/ml; were active against different human pathogenic bacteria. At concentration about 2.5 mg/ml, 100% of inhibition was recorded against both Gram-positive and Gram-negative bacteria. The result obtained with ethanol and methanol extracts of leaves; petroleum ether and chloroform extract of bark exhibited significant antibacterial activity, a property that supports traditional use of the plant in the treatment of some diseases as broad spectrum antibacterial agents.