Antioxidant profile of mono- and dihydroxylated flavone derivatives in free radical generating systems.

A number of free radical generating systems were used to investigate the antioxidant properties and structure-activity relationships of a series of monohydroxylated and dihydroxylated flavones. Ortho-dihydroxylated flavones showed the highest inhibitory activity on enzymic and non-enzymic microsomal lipid peroxidation as well as on peroxyl radical scavenging. Most flavones were weak scavengers of hydroxyl radical, while ortho-dihydroxylated flavones interacted with superoxide anion generated by an enzymic system or by human neutrophils. This series of compounds did not exert cytotoxic effects on these cells. Scavenging of superoxide and peroxyl radicals may determine the antioxidant properties of these active flavones.