Influence of flavonoids on cell cycle phase as analyzed by flow-cytometry

Flavonoids were previously reported to have cytostatic activity in vitro and in vivo. In the present study each phase of the cell cycle was observed by flow-cytometry after HCT-15 cells had been cultured with flavonoids for 2 days. In the control group, two peaks were observed on the histogram, the first peak representing double strands of DNA, and the second tetra strands. Chalcone, which is known to be a precursor of all flavonoids, seemed to block the passage from S to G(2) and M phases. Flavonone, which is freely transformed into chalcone in vivo, showed a similar histogram as chalcone. Among the anthocyanins most effective in suppressing the tumor cell growth, cyanin and pelargonidin made a mild rise between the Ist and 2nd peak suggesting block between G(1) and S phase. Delphinidin gave a high percent of cells in G(1) phase, suggesting prolongation of G(1) phase. When quercetin or kaempherol, both of which are flavonols were added to the culture, the second peak rose significantly, indicating a block between G(2) and M phases. Thus, the site of these cytostatic agents seems to differ depending on the kind of flavonoid.