ANTIOXIDANT PROPERTIES OF POLYPHENOLS EXTRACTED FROM GREEN AND BLACK TEAS

ABSTRACT The catechins, including epicatechin gallate (ECG), epigallocatechin (EGC), and epigallocatechin gallate (EGCG), and the theaflavins, including theaflavin (TF), theaflavin monogallate (TF‐1), and theaflavin digallate (TF‐2), were extracted from green tea and black tea, respectively. The 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical‐scavenging ability, superoxide‐scavenging efficiency, and lipid oxidation‐inhibition ability of the pure compounds listed above as well as epicatechin (EC), carnosol, carnosic acid, and butylated hydroxytoluene (BHT) were investigated. The DPPH radical‐scavenging ability of the catechins was EGCG > ECG > EGC > EC and of the theaflavins was TF‐2 > TF‐1 > TF. EGCG, ECG, EGC, TF‐2, TF‐1, and TF showed higher DPPH radical‐ and superoxide‐scavenging abilities than carnosol, carnosic acid, and BHT. EGCG, ECG, EGC, carnosol, and carnosic acid showed higher lipid oxidation‐inhibition activity, as measured by the Rancimat method, than BHT and theaflavins.