Tea extracts are source of polyphenols, which are antioxidant components. Green tea phenolic compounds are predominately composed of catechin derivatives, although other compounds such as flavanols and phenolic acids are also present in lower proportion.
The content of polyphenols in green tea is higher than those of black tea. Over the past few years, numerous studies have indicated that catechins and other polyphenols in tea exhibit powerful antioxidant activities.
Flavonoids (and their fraction – catechins) are the basic phenolic compounds in green tea responsible for antioxidant activities such as neutralization of free radicals that are formed in the process of metabolism. Free radicals are formed from molecules via breakage of a chemical bond such that each fragment keeps one electron, by cleavage of a radical to give another radical and, also via redox reactions. Free radicals are the main factors responsible for the initiation of formation of cancer cells.
Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions.
The main catechin compounds found in green tea are (-) Epigallocatechin Gallate (EGCG), that represents approximately 59% of the total content of catechins; (-) Epigallocatechin (EGC), 19%; (-)Epicatechin Gallate (ECG), 13.6%; and (-)Epicatechin (EC), 6.4% and also other compounds.
Chemical compound of antioxidants in green tea
