Figure 6.

Effect of flavonoids (1–10) at a concentration of 10 μM (pink) and 20 μM (red) on the intracellular accumulation of doxorubicin in resistant HL60/MDR cells. The accumulation was determined after 1 h of incubation of cells with doxorubicin (10 μM) in the presence or absence of the flavonoids 1–10 or verapamil (VERA, 20 μM used as a positive control) using flow cytometry doxorubicin accumulation assay. Results were expressed as the percentage ratio of the doxorubicin fluorescence in the presence of each modulator to the fluorescence of doxorubicin alone (Ctrl). The data show means ± SD of at least four independent experiments (* p < 0.05; ** p < 0.005).