Antibacterial and antifungal activity of Isatis tinctoria L. (Brassicaceae) using the micro-plate method

摘要

Isatis tinctoria L. has well-documented history as conventional therapeutic herb. In present study its crude extract was examined for broad-spectrum antimicrobial activity using micro-titer plate method. Four different plant parts were extracted with 14 different solvents. All fractions were analyzed against seven bacterial and four fungal strains. Ethyl acetate, chloroform, n-hexane and acetone showed maximum antibacterial activity with minimum IC 50 value (≤200 μg/ml). Leavesbranches rootsflower is the order of different parts based on antibacterial activity. Although, in some cases like against Klebsiella pneumonia and Micrococcus luteus the flower showed better results as compared to other parts. Roots showed better results against Staphylococcus aureus and Pseudomonas aeruginosa. Extracts showed better antimicrobial activity as compared to antibiotics (cefotaxime). The activity of the extracts against gram positive was better than gram negative. For antifungal activity, ethyl acetate n-hexane-ethyl acetate (1:1) chloroform acetone was the order of the fraction with increasing growth inhibition rate. All the parts (except branches) were observed having antifungal activity. The most resistant strains found in this study were Mucor mycosis, none of the fraction have more than 30% inhibition on used concentration. Plant crude extract being having broad spectrum antimicrobial activity is suggested for pre-clinical and clinical trials.