Abstract
(-)-Epigallocatechin-3-gallate (EGCG) is the most abundant of the green tea polyphenols. The properties ascribed to EGCG are anti-tumorigenic, anti-inflammatory, antioxidative, antiproliferative, antibacterial and antiviral effects. Recent studies also report pro-inflammatory and pro-apoptotic effects, with a mechanism of action through cell cycle progression inhibition. Its novel properties include inhibition of expression of the matrix metalloproteases-2 (MMP- 2) gene by direct binding. Studies have shown that EGCG interferes with HIV-1 viral infection by virion destruction and HIV-1 reverse transcriptase inhibition. Its anticancer activity includes suppression of ligand binding to different tyrosine kinase receptors (TKR), inhibition of protein kinase C (PKC), lipoxygenase (LOX), cycloxygenase (COX), and induction of apoptotic cell death. EGCG exerts its anti-carcinogenic property by down regulating COX-2. EGCG inhibited the catalytic activity of extra cellular signal regulated kinases (ERKs) and p38 mitogen-activated protein kinase (MAPK), which are upstream enzymes known to regulate COX-2 expression suggesting that these could be potential targets for the anti-tumor activity of EGCG. It selectively inhibits tyrosine kinase and MAPK in the transformed cells and downregulates Ras and Jun. In the present article we review the various mechanisms through which EGCG exerts its antiproliferative effects and its potential application as a natural drug against several proliferative diseases are discussed.
Keywords: catechins, egcg, lipoxygenase, cycloxygenase, tyrosine receptor kinases, map kinases, matrix metalloproteases, proteosome
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