Rubia tinctorum a root belonging to family Rubiaceae was evaluated for the antibacterial activity against a number of bacteria. We determine antibacterial activity of Alizarin, Purpurin, methanol and chloroform extracts of Rubia tinctorum roots against one gram positive and three gram negative bacteria using agar well-diffusion method. The minimum inhibitory concentration (MIC) was determined using micro dilution method. Extracts were dissolved in DMSO–d6 to obtain a concentration of 10% (w/v), and the density of bacterial suspension was 1.5 × 108 cfu/ml. The results showed a significant and promising activity towards Klebsiella pneumonia, Staphylococcus aureus, pseudomonas and E.coli. Additionally, the minimum inhibitory concentration (MIC) was determined and illustrated that, the most susceptible organisms to Alizarin ,purpurin ,methanol and chloroform extract was Klebsiella pneumonia with MIC of (12.5 , 6.25 , 3.125 , 1.562) mg/mL respectively .Therefore, R.tinctorum extract could be considered as promising source for effective antibacterial agent.
Key words : Rubia tinctorum