ABSTRACT
Flavonoids may be useful for the prevention or treatment of free-radical-associated diseases; hence, much attention has been paid to the physiological functions of flavonoids as antioxidants. However, there was a lack of information on the molecular mechanism in which flavonoids play the antioxidative role. It has been reported that their function is strongly dependent on their structural properties. We have already studied the oxidation of quercetin with hydrogen peroxide and sodium hypochlorite in alcoholic aqueous solution and determined the structure of the two major oxidation products (Figure 27.1). Through the structural analysis of the oxidation products, it was suggested that the hydroxyl group at the C-3 position in the C ring plays an important role in the antioxidative action. In this study, we oxidized morin by sodium hypochlorite and determined the structure of the oxidation products. Additionally, we compared the antioxidative activity of two flavonoids with that of their oxidation products and discussed the structureantioxidant activity relationships between these flavonoids. The result indicated
that the positions of hydroxyl groups in the B ring affect the electronic state and structural geometry of flavonoids.
