evaluating the effect of dracocephalum kotschyi methanol extract on mycobacterium tuberculosis

background and objectives: tuberculosis (tb) is the major public health problem in the world. each year there are 2-3 million deaths worldwide caused by tb. the increasing incidence of multi drug resistance tuberculosis (mdr-tb) worldwide highlights the urgent need to search for new anti-tuberculosis compounds. it has been reported that medicinal plant, dracocephalum kotschyi, possesses some antibacterial effect, thus in the present study its anti-mycobacterial property was evaluated. methods: the sensitivity and resistance of m. tuberculosis strains at concentration of 0.2 µg/ml isoniazid was determined by proportion method. methanol extract of d. kotschyi was prepared using maceration method. six concentrations of d. kotschyi, including 20, 40, 80, 160, 320 and 640μg/ml were prepared and its anti-mycobacterial effect on four groups of m. tuberculosis including m. tuberculosis h37rv (atcc 27294), isoniazid susceptible and resistance and mdr strains was determined. results: the methanol extract of d. kotschyi was significantly against m. tuberculosis. the percent of growthwas decreased from 100% to 0% in m. tuberculosis  h37rv (atcc 27294),  isoniazid resistant and isoniazid susceptible strains but from 100% to 50% in mdr strain in 640 μg/ml concentration. conclusion: the results showed that different concentrations of d. kotschyi methanol extracts showed a remarkable inhibitory effect on m. tuberculosis. identification of the effective fraction of d. kotschyi against m. tuberculosis is a further step to be studied.