INVOLVEMENT OF PHENOXYL RADICAL INTERMEDIATES IN LIPID ANTIOXIDANT ACTION OF MYRICETIN IN IRON-TREATED RAT HEPATOCYTE CULTURE

Supplementation of rat hepatocyte cultures with the flavonoid myriceti n (300 mu M) led to the formation of phenoxyl radical intermediates, a s detected in intact cells by electron paramagnetic resonance (EPR) sp ectroscopy. These radicals corresponded to one-electron oxidation prod ucts of myricetin. The level of phenoxyl radicals was significantly re duced when myricetin-treated hepatocyte cultures were also supplemente d with iron (Fe-NTA 100 mu M). This suggested that iron could accelera te the oxidation flux of myricetin. Moreover, myricetin was found to b e able to inhibit lipid peroxidation induced by iron in hepatocyte cul ture. Free malondialdehyde (MDA) levels and the amount of radicals der ived from oxidized lipids were greatly reduced when myricetin was adde d to iron treated cultures. This showed that myricetin was a good inhi bitor of lipid peroxidation in this model and that the intermediate ge neration of phenoxyl radicals might contribute to the antioxidant mech anism of myricetin. (C) 1998 Elsevier Science Inc.