Spectrophotometric measurement of antioxidant properties of flavones and flavonols against superoxide anion

The antioxidant properties of 12 hydroxyflavones (including flavonols) and eight methoxyflavones were evaluated using the pyrogallol UV-VIS spectropho tometric method to generate superoxide anion. Pro- and antioxidant activity depends of the flavone concentration in the medium. Results show that the hydroxylation (on the C ring) of the 3- position (flavonols) enhanced antio xidant properties more than methoxylation. A similar phenomenon is observed for hydroxylation at the 2'-and 4'-positions (B ring). Hydroxylation or me thoxylation on the 7- position (A ring), however, has a negative effect on the radical scavenger activity. (C) 2000 Elsevier Science B.V. All rights r eserved.