Natural products such as green tea have attracted a great deal of attention in the last decade because of its potent anti-oxidant properties and distinct anti-cancer activity. Catechins are important constituents of green tea and belong to the natural product class of flavonoids. The green tea flavonoids are rich in phenolic antioxidants, which are believed to be responsible for the chemoprotective potential of the tea extracts. The major polyphenolic constituents found in green tea are (-)-epicatechin, (+)-catechin, (-)-catechin, (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG) & (-)-epigallocatechin (EGC).
Eco-Friendly Starting Materials
Commercially prepared green tea extracts are standardized to contain 50-60% polyphenols. Recent studies have revealed that the naturally occurring polyphenolic catechins inhibit some forms of breast cancer cell proliferation1 and tumor growth and prevent recurrence in some forms of Stage I-II breast cancer in women2. Green tea polyphenols have also been used as chemopreventive agents for skin cancer3 and for the reduction in cancer of colon, pancreas, rectum and lungs. These flavonoids have also found to possess anti-inflammatory, antiallergic, antithrombotic and antiviral properties. To date the efficacy of these flavonoids in cancer therapy is still low as compared to commercial available anticancer drugs. One of the reasons for this is the variability of catechin preparations when they are extracted from natural sources and the lack of standard for measuring the activity of various preparations distributed to investigators. However, these flavonoids provide tremendous opportunity as eco-friendly starting materials that can be chemically/enzymatically modified to yield a range of flavonoid analogues with improved efficiency.
Most drugs used to treat breast cancer are highly toxic. Green tea flavonoids used here as starting materials, polymerized using “green” chemistry, yields highly active & stable products that are biocompatible and can be tolerated by humans to much higher dose levels (>2g/day) as compared to commercial drugs.
A major innovation in the proposed research is the simplicity of the approach to synthesize antitumorigenic compounds based on polycatechins. These studies should lead to the development of a new family of chemotherapeutics that are well tolerated in vivo, with a high therapeutic ratio demonstrated in vitro and in vivo against primary and metastatic human tumor cells.