Antioxidant effects of metronidazole in colonic tissue.

Reactive oxygen species, primarily generated in the mitochondria, contribute to tissue injury in inflammatory bowel diseases. The efficacy of metronidazole (MTZ) in some situations of inflammatory bowel disease may result not only from its antibiotic effect, but also from an antioxidant effect. We evaluated, under physiologic conditions, the antioxidant potential of MTZ on the biomarkers of oxidative damage to proteins (protein carbonyls), lipids (malondialdehyde), and the levels of antioxidant defense (glutathione) in the small bowel, large bowel, and liver of control and MTZ-treated rats. Basal levels of protein carbonyls and malondialdehyde were significantly higher in the colon compared with those in the small intestine, whereas glutathione levels were quite similar along the bowel. MTZ reduced significantly the colonic oxidative damage to proteins without any side effect in the liver. This is the first evidence of an antioxidant effect of MTZ on oxidative protein damage in the colon under physiologic conditions.