growth inhibition and apoptosis induction by vincetoxicum pumilum decne. on hl-60 and k562 leukemic cell lines

Background: phenanthroindolizidine alkaloids have been isolated from many species of vincetoxicum. these alkaloids show promising anti-cancer activity and are a current topic of interest. objectives: the inhibition of cell viability by different extracts of v. pumilum was measured in vitro in hl-60 and k562 human leukemic cancer cell lines and in freshly-isolated peripheral blood lymphocytes as a normal cell line. materials and methods: using resazurin staining, cell viability was measured. in addition, the presence of apoptotic cells was determined using propidium iodide (pi) staining of dna fragments (sub-g1 peak). employing western blot analysis, levels of bax, bcl-2, and parp cleavage were measured. results: thech2cl2 fraction of v.pumilumshoweda potent dose-related inhibitory effectoncell viability. thech2cl2 fractionshowed ic50 values of 8.3 and 12.5 g/ml in the k562 and hl-60 cell lines, respectively. a sub-g1 peak in the flow cytometry histograms of treated cells induced by the ch2cl2 fraction suggested an induction of apoptosis. further, both the parent methanol extract and its ch2cl2 sub-fraction increased the expression of the pro-apoptotic protein bax and of cleaved parp in the cells. conclusions: collectively, the v. pumilum extracts showed remarkable cytotoxic activity and merit further investigation as anticancer agents.