PROOXIDANT ACTIVITY OF FLAVONOIDS - EFFECTS ON GLUTATHIONE AND GLUTATHIONE-S-TRANSFERASE IN ISOLATED RAT-LIVER NUCLEI

The effects of three representative flavonoids, quercetin, myricetin a nd kaempferol, on the nuclear antioxidant defense glutathione (GSH) an d glutathione S-transferase (GST) were investigated in a model system of isolated rat liver nuclei. The three flavonoids induced a concentra tion-dependent decrease of both the nuclear GSH content and GST activi ty. Myricetin, which has the maximum number of hydroxyl groups, was th e most active. The results demonstrate the pro-oxidant activity of the se polyphenolic flavonoids. The impairment of the nuclear antioxidant defense GSH and GST by the polyphenolic flavonoids can lead to oxidati ve DNA damage, which may be responsible for their mutagenicity.