Bacitracin and a bacitracin-zinc complex damage DNA and carbohydrate in the presence of iron and copper salts.

The antibiotic bacitracin binds metal ions such as zinc, copper and iron, and is often prepared for clinical and veterinary use as a zinc complex to enhance stability. Here, we show that bacitracin and its zinc complex are able to reduce copper and iron salts with the formation of hydrogen peroxide. This results in damage to the bacitracin molecule and the release of some oxidising radicals into free solution that attack detector molecules such as deoxyribose and DNA. Damage to deoxyribose and DNA can be detected by the formation of thiobarbituric acid-reactive material and this damage can be protected against by the addition of scavengers of the hydroxyl radical implicating the OH radical in the degradation observed.