Tea (Camellia sinensis) is native to the southern regions
of China and parts of India, Laos, Thailand, Vietnam,
and Myanmar [1].Green tea refers to non-fermented tea, in which the
oxidation of the tea polyphenols, called catechins, is
prevented by quickly heating the leaves after harvest to
inactivate the main oxidising enzyme, polyphenol oxidase
(PPO), and thus, most of the catechins are preserved during
the processing.As catechins can donate
hydrogens from the hydroxyl groups in their structure, they
have been found to have excellent antioxidant activities,
expressed through their free radical scavenging ability being
more powerful than vitamin C, vitamin E, or b-carotene
[5-7].In these teas, aerobic
oxidation of the tea leaf polyphenolics is allowed to occur
and the catechins are enzymatically catalysed to form thea flavins and thearubigins.In addition, green tea and its catechins have been
linked with reductions in cardiovascular disease, dental
decay, obesity, diabetes, and an improvement in the
immune systemThe recent in vivo
and epidemiology studies have linked the green tea cate chins with the prevention of some skin and liver cancers
[8-11].They have also been shown to chelate transition metal
ions, modulate oxidant and antioxidant enzymes, and affect
gene expression [5].