Comparative evaluation of cytotoxicity and antioxidative activity of 20 flavonoids.

Flavonoids are common dietary components with many health benefits shown through epidemiological studies. However, the fact that flavonoids also act as pro-oxidants and mutagens makes the safety of flavonoids uncertain when used at higher doses. To give a preliminary evaluation on the correlation between beneficial and harmful effects of flavonoids, the antioxidative activity and cytotoxicity of 20 flavonoids from food and herbs were investigated in vitro. The results indicated that luteolin, hydroxygenkwanin, and kaempferol possessed significant dual properties, whereas flavokawain B, flavokawain C, cardamonin, and uvangoletin showed a marked cytotoxicity. The relationships between structure and antioxidant and cytotoxic activity are intensively discussed. In view of the toxicity, the intake of flavonoids in large amounts should not yet be encouraged.