Evaluation of phenolic constituents and antioxidant activity of aqueous extracts of Kangra tea [Camellia sinensis (L) O Kuntze]

Abstract

Consumption of green tea (Camellia sinensis) may provide protection against chronic diseases, including cancer. Green tea polyphenols are believed to be responsible for this cancer preventive effect, and the antioxidant activity of the green tea polyphenols has been implicated as a potential mechanism. The objective of this study was to determine the relationship between the plucking periods and the major constituents and the antioxidant activity in green tea. The mean values of total catechin content varied significantly in the range of 130.51 to 96.79 g kg-1 for Kangra Local; 111.18 to 82.09 g kg-1 for Kangra Asha and 136.56 to 99.26 g kg-1 for Kangra Jawala. The mean monthly total phenol content varied significantly in the range of 175.843 to 135.407 g kg-1for Kangra Local; 230.360 to 109.863 g kg-1 for Kangra Asha and 223.036 to 184.639 g kg-1 for Kangra Jawala. In addition, antioxidant activity of green tea and standard catechins was investigated using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay. The order of antioxidant activity of standard catechins was as follows: EGCG> EGC ≥ ECG ≥ EC ≥ C. Moreover, the cis-catechins contents were the key factor affecting the antioxidant activity of green tea.