Role of Catechins in Chemosensitization

Anticancer drugs are now frequently being combined with dietary phytochemicals/nutraceuticals in an effort to enhance their antitumor efficacy while lowering their toxic effects. This forced the research to shift toward traditional medical practices with some advancement, that is, the use of nutraceuticals such as catechins. Catechins and their gallate esters are a class of polyphenolic compounds that has recently attracted a great deal of attention because of its beneficial effect on human health. They are functionally versatile and regulate a number of biological pathways to deal with various physiological or pathophysiological pathways. Catechins are mostly known for their potent antioxidants activity; however, depending on the doses, they may also show prooxidant effects. Reports on green tea catechin-mediated modulation of several key cellular functions associated with strong chemoprotective and chemosensitizing properties have been often ascribed to both anti- and prooxidant activities. Catechins hit multiple targets in cancer therapy and are also found to be useful in managing multidrug-resistant tumors. Catechins have been shown to suppress several key pathways linked to oncogenesis, including those involved in cell survival, proliferation, and invasion, along with angiogenesis. They are also helpful against disorders involving lipid and glucose metabolism such as type 2 diabetes and obesity and could also alleviate the risk of cardiovascular diseases. The beneficial effects of catechins especially EGCG have been reported from in vitro and in vivo studies in model organisms and from some pilot studies in preclinical and clinical trials. Catechins, potent antioxidants with biological activity relevant to the prevention and treatment of cancer, are actively being tried in combination with many chemotherapeutic drugs in order to increase the efficacy of the chemotherapeutic drugs and to ameliorate the drug-associated side effects.