Polyphenols and flavonoids from natural products possess antioxidant properties which are known to prevent as well as treat cancer. Natural compounds from plant kingdom are non-toxic in a wide range of concentrations and are safe for long term usage. Many studies have demonstrated anticancer properties of many polyphenols and other antioxidants involving cell cycle modulation, transcription factor NF-κB and protein kinases. Research results from our laboratory have shown enhanced cytotoxic activity of a number of polyphenols, such as triphala, ellagic acid, curcumin, biochanin A and others in tumor cells in combination with radiation whereas normal cells were protected against the damage. The present paper gives a brief review of differential action of polyphenols in tumor and normal cells and outlines the mechanism of action through induction of apoptosis in oxidatively stressed cells. It is suggested that antioxidants drive cells to survival or death depending upon the level of homeostasis. Results point to clinical evaluation of some of these polyphenols for practical applications in cancer radiotherapy.
Keywords: Polyphenols; Cancer; Antioxidants; Oxidative Stress; Chemoprevention.