Abstract

The in vitro antimicrobial activity of Justicia adhatoda, Glycyrrhiza glabra andHyssopus officinalis extracts were studied against selected bacteria by using agar well diffusion assay. Methanol, ethanol, chloroform, diethyl-ether and aqueous extracts were tested in crude form for antibacterial activity against Bacillus subtillus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium and Staphylococcus aureus. Maximum antibacterial activity was exhibited by all the three plant extracts. The results obtained with P. aeruginosa were particularly interesting since it was not inhibited by the antibiotic used but the tested plant extracts effectively inhibited the growth of P. aeruginosa. The methanolic extract ofJ. adhatoda was effective against S. typhimurium. All the plants extract in water were effective against spore forming of B. subtillus while S. aureus and E. coli were not effectively inhibited by extracts of tested plants. The results of analysis of variance have shown significant differences between the species, treatments and interaction between the species and treatments. However, the differences were non-significant between the treatments for G. glabra. The results indicate that J. adhatoda, G. glabra and H. officinalis present a noteworthy potential of antibacterial activities.

Key words: Justicia adhatoda, Glycyrrhiza glabra, Hyssopus officinalis, antimicrobial assay.