Quercetin, a bioflavonoid, inhibits the DNA synthesis of human leukemia cells

Quercetin, a flavonoid, is found in many plants, including edible fruits and vegetables. It has been proposed that flavonoids may have potential as anticancer agents. To test an aspect of this hypothesis, we examined the effects of the flavonoid, quercetin, on the DNA synthesis of the human leukemia cell, HL-60. Quercetin induced a dose-dependent inhibition of DNA synthesis in the test range of 1 microM to 1 mM. The inhibitory effect on DNA synthesis was evident as early as 24 h after the addition of quercetin. At the concentrations of 10 microM, 100 microM and 1 mM, 50, 82 and 85% of DNA synthesis, respectively, was inhibited by quercetin as compared to the control. After 48 and 72 h incubation of the cells with 100 microM and 1 mM quercetin, DNA synthesis was almost completely abolished. These results suggest that the inhibitory effects of quercetin on HL-60 cell DNA synthesis is not due to a non-specific cytotoxic effect, since following removal of quercetin, the treated cells regrew normally.