Effect of aqueous extracts from black tea on free radical scavenging

Eight kinds of catechins and three kinds of theaflavins were analyzed by HPLC after water-soluble components extracted from three kinds of black tea.Then,free radical scavenging abilities including 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS)radical scavenging ability,1,1-diphenyl-2-picrylhydrazyl(DPPH)radical scavenging ability,and ferrous-ion chelating(FIC)ability of different concentration aqueous extracts were evaluated.The results showed that the order of catechins contents was Yinghong Qihong Dianhong,and the order of theaflavins contents was Yinghong Dianhong Qihong.Three black tea aqueous extracts showed significant ABTS and DPPH radical scavenging activity and ferrous-ion chelating ability.Moreover,percent DPPH and ABTS radical scavenging abilities and ferrous-ion chelating ability of black tea aqueous extracts were dose-dependent.