Background: Chronic myeloid leukemia (CML) is a malignant clonal disorder of hematopoietic stem cells which results in increase of myeloid cells, erythroid cells and platelets in the peripheral blood and hyperplasia in bone marrow. The research evaluates the cytotoxic effect of hydro-alcoholic extract of M.polegium before flowering aerial organs on K562 cell line as a model of chronic myeloid leukemia.

Materials and Methods: In this experimental trial, Leaves and stems of M. pulegium before flowering collected from Afoos city and extraction using maceration method. K562 cells were cultured and treated with concentrations of extract (12.5-100 &mug/ml) and different times (24,48,72 hour). Cytotoxicity of M. pulegium before flowering extract against K562 leukemia cells was estimated by the MTT test method. The absorbance was measured using an ELISA plate reader at 540 nm. Survey on data accomplished with the use of SPSS15 software and one-way ANOVA test analysis and Tukey test and p<0.001 was considered significant.

Results: Hydro-alcoholic extract of Mentha pulegium before flowering showed the highest cytotoxic effect (IC50=50 &mug/ml) and 72 hour after treatment on K562 cell line .in other words, hydro-alcoholic extract of Mentha pulegium before flowering extracts a dose and time dependent cytotoxic effect on K562 cell line.

Conclusion: Considering the cytotoxic effect of hydro-alcoholic extract of M.polegium before flowering aerial organs on K562 cells, the plant can be considered as a potential candidate for further studies on CML treatment.