Free radical scavenging abilities in vitro and antioxidant activities in vivo of black tea and its main polyphenols

Abstract

In the present study, in vitro free radical scavenging abilities and in vivo antioxidant activities of Assam black tea extract (ASTE) and theaflavins mixture (TFSM) were investigated. Our results showed that ASTE and TFSM had significant free radical scavenging activities in vitroin a dose-dependent manner, especially 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical. For antioxidant activities in vivo, the mice were fed with ASTE and TFSM everyday. The contents of malondialdehyde (MDA), and the activities of superoxide dismutase (SOD) and glutathione per- oxidase (GSH-Px) in the mice serum and liver were measured after 30 days. As a result, TFSM could obviously improve SOD and GSH-Px activities, and reduce MDA content in the serum and liver. Though ASTE also showed a certain antioxidant activity, it was slightly weaker than the antioxidant activity of TFSM in the mice. Moreover, ASTE did not change the activity of GSH-Px in the mice liver. In conclusion, our results showed that black tea and its main polyphenols were effective in scavenging DPPH, ABTS and OH free radicals in vitro, and increasing the SOD and GSH-Px activities, decreasing the MDA contents in the mice. These findings suggest the important significance of black tea consumption in prevention of diseases. Key words: Black tea, polyphenols, antioxidant, theaflavin.