Protective Effects of (-)Epigallocatechin Gallate and (+)Catechin on Nitrogen Oxide-Induced Sister Chromatid Exchange

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The protective effects of green tea polyphenols on nitrogen oxide (NOx)-induced sister chromatid exchange (SCE) in cultured cells were studied. (-)Epigallocatechin gallate (EGCG) and (+)catechin (CT), the major polyphenol constituents of green tea, were found to reduce the frequency of SCE induced by NOx. NO releaser (NOR4)-released NO and NaNO₂ were used as NOx. Significantly fewer SCEs were induced by 30 μM NOR4 and NaNO₂ after the treatment of cells with 0.1 μM EGCG or 0.5 μM CT. NOx (NO, NO₂^-) is a potent environmental pollutant owing to its carcinogenic properties. Therefore these experimental results indicate the protective effects of green tea against NOx-type carcinogens.