DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity of flavonoids obtained from some medicinal plants

A reactive oxygen species has been implicated in a range of human pathologi cal diseases such as atherosclerosis and certain cancers. Flavonoids are re ported to exhibit various biological activities, including antioxidative an d free radical scavenging activities. Several flavonoids obtained from. bar ley leaves, soybean and some medicinal plants, Silybum marianum, Sophorae F los, Cinnamon, Ephedrae Herba and Scutellariae Radix, were tested for their DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity. The stru cture-activity relationships suggested that not only the numbers of hydroxy group but also the position of hydroxy group might be important for mediat ing potent activity.