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Inhibition of 1,2-dimethylhydrazine-induced oxidative DNA damage in rat colon mucosa by black tea complex polyphenols
M Lodovici1, C Casalini, C De Filippo
1Department of Pharmacology, University of Florence, Italy. maura@pharm.unifi.it
Abstract:
The effect of black tea polyphenols on 1,2-dimethylhydrazine (DMH)-induced oxidative DNA damage in rat colon mucosa has been investigated. Fischer 344 rats were treated orally with thearubigin (TR) or theafulvin (TFu) for 10 days (40 mg/kg), injected ip with DMH (20 mg/kg) or saline and sacrificed 24 hr after DMH administration. The levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) were measured in colonic mucosa DNA and expressed as a ratio relative to 2'-deoxyguanosine (2dG). Control rat mucosa had 8-OHdG values of 1.12 +/- 0.14/10(5) dG (mean +/- SEM, n=11), whereas DMH-treated rats significantly higher values (1.52 +/- 0.14/10(5) dG, n=26, P<0.05). Pretreatment of rats with TR had significantly inhibited DMH-induced oxidative DNA damage 0.99 +/- 0.09/10(5) dG, n=10, P<0.05) and a similar, although less marked, effect was observed with TFu (1.15 +/- 0.19/10(5), n=9, P=0.06). These findings confirm that DMH causes oxidative DNA damage in the colon mucosa of rats and demonstrate that this effect is prevented by the consumption of complex polyphenols from black tea.
Insights
Black tea polyphenols, specifically thearubigin and theafulvin, significantly protected against 1,2-dimethylhydrazine (DMH)-induced oxidative DNA damage in rat colon mucosa. This research highlights black tea
Area of Science:
- Biochemistry
- Toxicology
- Nutritional Science
Background:
- 1,2-dimethylhydrazine (DMH) is a chemical agent known to induce oxidative DNA damage.
- Oxidative DNA damage in the colon mucosa is a significant concern in gastrointestinal health.
- Polyphenols, particularly those found in black tea, are recognized for their antioxidant properties.
Purpose of the Study:
- To investigate the protective effects of black tea polyphenols against DMH-induced oxidative DNA damage.
- To quantify the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) as a biomarker of oxidative DNA damage.
- To compare the efficacy of thearubigin (TR) and theafulvin (TFu) in preventing DNA damage.
Main Methods:
- Fischer 344 rats were orally administered thearubigin or theafulvin for 10 days.
- Rats were injected with 1,2-dimethylhydrazine (DMH) or saline.
- Levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in colonic mucosa DNA were measured and normalized to 2'-deoxyguanosine (2dG).
Main Results:
- DMH treatment significantly increased 8-OHdG levels in rat colon mucosa compared to controls.
- Pretreatment with thearubigin significantly inhibited DMH-induced oxidative DNA damage.
- Theafulvin showed a similar, though less pronounced, protective effect against DMH-induced DNA damage.
Conclusions:
- DMH reliably induces oxidative DNA damage in the rat colon mucosa.
- Complex polyphenols present in black tea, such as thearubigin and theafulvin, demonstrate chemopreventive potential.
- Consumption of black tea may offer protection against colon oxidative DNA damage.