Cancer is the second most common disease related cause of death in the USA. A combination of epidemiological and basic science evidence strongly suggests that diet and plant-derived phytochemicals may play an important role in cancer prevention. Thus, there is an urgent need for research on phytochemicals which may prevent cancer or which may be useful adjuncts in the prevention of cancer recurrence among successfully treated cancer survivors where prevention of cancer recurrence is vital. Green Tea contains potent antioxidants called polyphenols that have been shown to reduce tumor growth and metastasis capacity and angiogenesis in several studies. The four major catechins in green tea are: (-)-epicatecchin, (-)-epicatechin-3-gallate, (-)-epigallocatechin, and (-)-epigallocatechin-3-gallate (EGCG). EGCG is the main component, accounting for 40% of the total polypenolic mixture, but it is not clear that this is the only component important in the action of green tea. Preliminary work suggests that these polyphenols protect DNA more than either Vitamin E or beta-carotene in the retro-Ames assay. Anti-angiogenic strategies differ from other therapeutic agents because they are based on static effects on tumors and require prolonged administration. Dietary supplements such as green tea would be perhaps useful alone or in combination of other anti-angiogenic agents. The studies outlined in this proposal are aimed to compare the activities of standardized Green tea extracts and purified EGCG to provide a critical scientific support for future clinical studies of green tea dietary supplements versus proceeding with EGCG. Thus, the aims are: To compare EGCG with green tea catechin extract, examining DNA protection, and tumor cell growth.
This aim will determine whether the antioxidant and DNA protective effects of green tea are due to other constituents other than ECGC. To compare anti-angiogenic potency of EGCG and green tea extract in vitro and in vivo.
This aim will determine whether the growth inhibitory effects induced by green tea are due to EGCG or to additional catechins in the green tea mixture. To compare the bioavailability and antioxidant bioactivity of EGCG and mixed green tea catechins by measuring polyphenols, oxygen radical absorbing capacity (ORAC), lipid peroxidation, and white cell DNA base damage in timed blood samples from normal volunteers.
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