Inhibition of 1,2‐Dimethylhydrazine‐induced Oxidative DNA Damage by Green Tea Extract in Rat

Following subcutaneous injection of 1,2‐dimethylhydrazine (DMH), which is carcinogenic to rat colon and liver, to Sprague‐Dawley rats, a significant increase of 8‐hydroxydeoxyguanosine (8‐OHdG) was observed in the DNA of colonic mucosa and liver. The 8‐OHdG formation reached the maximal level at about 24 h after the DMH injection. On the other hand, no increase of 8‐OHdG was observed in the DNA of the kidney. Drinking green tea extract (GTE) for ten days prior to the DMH injection significantly inhibited the formation of 8‐OHdG in the colon. These findings demonstrate that DMH causes oxidative damage to the DNA of its target organ, and that GTE protects colonic mucosa from this oxidative damage.