In vitro Antimicrobial Activity and Qualitative Phytochemical Analysis of Withania somnifera (L.) Dunal Extracts

摘要

The antibacterial activity of various solvent extracts of stem of Withania somnifera was evaluated against gram negative bacteria Escherichia coli, Serratia marcescens, Pseudomonas aeruginosa and gram positive bacterium Bacillus cereus by agar well diffusion method. While antifungal activity of same extracts was evaluated against Aspergillus niger, Aspergillus flavus, Aspergillus oryzae, Penicillium chrysogenum and Trichoderma viridae. All the extracts showed significant antimicrobial potential against different test bacteria. Most susceptible organism in the investigation was S. marcescens against which all of the plant extracts showed zone of inhibition. Maximum antibacterial activity was recorded for methanol extract of W. somnifera stem against E. coli (ZOI of 17.67±1.52 and AI of 0.974) followed by B. cereus (ZOI of 15 ± 1.0 and AI of 0.993). Ethyl acetate extract was least inhibitory towards all the bacterial strains. The range of MIC of extracts recorded was 3.125 to 50 mg/ml. In the present investigation lowest MIC value 3.125 mg/ml was recorded for methanol extract against B. cereus and E. coli. In case of antifungal study, most susceptible organism in the investigation was T. viridae against which all of the plant extracts showed inhibition zone. A. flavus, A. oryzae and P. chrysogenum were proven to be resistant against all the extracts used in the study. Lowest MIC value 50 mg/ml was recorded for methanol and ethyl acetate extracts against T. viridae. Qualitative phytochemical analysis indicated presence of different phytochemicals in different extracts.