Polyphenolic composition and antioxidant activity of Kenyan Tea cultivar

Abstract

Polyphenolic fractions in tea are potent bioactive molecules. In this study, the polyphenolic composition of 25 different types of Kenyan tea cultivars was determined using the HPLC and the Folin’s-Ciocalteu spectrophotometric methods. Total Polyphenols, Total Catechins, individual catechins and Antioxidant Activity were significantly (P<0.05) different among tea varieties, with green tea had the highest levels of Total Polyphenols ranging from (19.70-26.12%), TC (8.51%-17.60%), individual catechins, and AA (86.65-94.50%). In vitro bioassay carried out using 2, 2’-diphenyl picrylhydrazyl radical showed epigallocatechin gallate was the most potent catechin and the most potent in antioxidant activity (r=0.968***). Epigallocatechin (r=0.659***, p<0.001), Epicatechigallate (r=0.454*, p<0.001) and Epicatechin (EC) (r=0.780***, p<0.001) showed significant (p<0.05) antioxidant activity. Black tea contained high levels of Theaflavins and Thearubigins (2.072% to 17.12%), respectively) which accounted for its antioxidant activity (r=0.803*** and r=0.859***, respectively). Gallic acid also showed significant (r=0.530*) contribution to the antioxidant activity in black tea. Data obtained from this study reveals that different Kenyan tea cultivars have different polyphenolic composition which imparts on their unique biochemical qualities. Green and white tea products are rich in catechins, black tea products are rich in TFs and TRs while purple teas are rich in anthocyanins.