Chapter 24 - Green Tea and Skin Cancer: Immunological Modulation and DNA Repair

Abstract

The characteristic aroma and health benefits of green tea are associated with the presence of catechin/epicatechin derivatives, which are commonly called “polyphenols.” The major polyphenolic constituents present in green tea are (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin-3-gallate, and (-)-epigallocatechin-3-gallate (EGCG). These polyphenols are antioxidant and anti-inflammatory in nature and have been shown to possess anticarcinogenic activity in several in vitro and in vivo systems. EGCG is the major and most effective chemopreventive agent and has been extensively studied in several disease models including its use in skin photoprotective activity. In addition to a small amount of catechins, black tea contains thearubigins and theaflavins, which are the polymerized forms of catechin monomers and are the major components formed during enzymatic oxidation and fermentation processes. The experimental evidence from several in vitro and in vivo studies indicates that the green tea polyphenols (GTPs) are better chemopreventive in nature than those present in black tea. The chapter describe the photoprotective potential, in particular antiphotocarcinogenic potential, of green tea polyphenols and their mechanisms of action, specifically the recent developments on the photoimmunology and DNA repair mechanisms in prevention of photocarcinogenesis by GTPs or EGCG. It has been shown that green tea can protect against both UVA and UVB radiation-induced skin cancer in mice. Also, the regular use of chemopreventive agents, such as green tea polyphenols, might be useful for the prevention of UV-induced immunosuppression in humans.