DNA degradation by water extract of green tea in the presence of copper ions: implications for anticancer properties
- 15 April 2003
- journal article
- research article
- Published by Wiley in Phytotherapy Research
- Vol. 17 (4) , 358-363
- https://doi.org/10.1002/ptr.1149
Abstract
In recent years a number of reports have documented the chemopreventive effect of green tea consumption on various types of cancers such as those of bladder, prostate, esophagus and stomach. This property is attributed to the presence in green tea of polyphenols known as catechins. These include epigallocatechin-3-gallate, epigallocatechin and epicatechin. In addition to their antioxidant properties plant derived polyphenolics are also capable of oxidative DNA damage particularly in the presence of transition metal ions. We have recently proposed a mechanism for cytotoxic action of plant-derived polyphenols against cancer cells that involves mobilization of endogenous copper and consequent prooxidant action. In partial support of the idea, in the present paper we show that water extract of green tea is considerably more efficient than black tea extract in DNA cleavage in the presence of copper ions. Green tea extract also shows a higher rate of Cu(II) reduction and consequent hydroxyl radical formation. Cu(II) reduction is presumably accompanied by the formation of ‘oxidized species’ of tea polyphenols, which in turn also appear to catalyze the reduction of Cu(II) leading to redox cycling of copper ions. The results are discussed in relation to the structural differences between polyphenols of green and black tea. Copyright © 2003 John Wiley & Sons, Ltd.Keywords
This publication has 22 references indexed in Scilit:
- Putative Mechanism for Anticancer and Apoptosis‐Inducing Properties of Plant‐Derived Polyphenolic CompoundsIUBMB Life, 2000
- A Novel Apoptosis-like Pathway, Independent of Mitochondria and Caspases, Induced by Curcumin in Human Lymphoblastoid T (Jurkat) CellsExperimental Cell Research, 1999
- Green Tea Constituent Epigallocatechin-3-Gallate and Induction of Apoptosis and Cell Cycle Arrest in Human Carcinoma CellsJNCI Journal of the National Cancer Institute, 1997
- Antioxidant, Gallic Acid, Induces Apoptosis in HL-60RG CellsBiochemical and Biophysical Research Communications, 1994
- A role for metals and free radicals in the induction of apoptosis in thymocytesFEBS Letters, 1994
- Programmed cell death (apoptosis) and response to anti-cancer drugsAnti-Cancer Drugs, 1994
- Bcl-2 inhibition of neural death: decreased generation of reactive oxygen speciesScience, 1993
- Tea and CancerJNCI Journal of the National Cancer Institute, 1993
- Quantitative analysis of copper, zinc and copper/zinc ratio in selected human brain tumorsJournal of Neuro-Oncology, 1993
- Green tea composition, consumption, and polyphenol chemistryPreventive Medicine, 1992