Abstract

The present study was conducted to evaluate the antimicrobial activity of various extracts (viz. methanol, acetone and ethyl acetate) of Thuja orientalis and its preliminary phytochemical screening. In vitro antimicrobial activity was tested by agar well diffusion assay against human pathogenic microbes which are Gram positive (viz. S. aureus andB. subtilis), Gram negative bacteria (viz. P. aeruginosa, A. faecalis and K. pneumoniae) and fungi (A. flavus and A. niger). Methanol and acetone extract of leaf exhibited maximum activity against B. subtilis with zones of inhibition of 20.33 mm and 17.83 mm, respectively. All the extracts of stem were found to be most effective against P. aeruginosa. S. aureus was found to be sensitive to leaf extracts prepared in methanol, acetone and ethyl acetate with 13.66, 14.03 and 15.00 mm zone of inhibition, respectively.A. flavus and A. niger, both were found to be sensitive towards the methanol extract of leaf with inhibition zones of 15.50 and 16.00 mm, respectively compared to fungicides (viz. ketoconazole and fluconozole). Methanol extract of leaf and ethyl acetate extract of stem exhibit marked antimicrobial activity against B. subtilis and P. aeruginosa, which was comparable to standard antibiotics (that is, penicillin, ampicillin, tetracycline and streptomycin). It was also observed that leaf extracts were more effective as compared tostem extracts of the plant. Thus, Thuja orientalis could be considered as potential source of natural antimicrobials used for the treatment of bacterial and fungal infections.

Key words: Plant extracts, antibacterial activity, minimal inhibitory concentration, phytochemical screening.