Reactive oxygen species deleterious effects

A molecule that has a prooxidant effect can be dehned as a molecule that can react with reactive oxygen species (ROS) to form compounds more deleterious to biomolecules than the ROS alone. Possible prooxidant activity of carotenoids was for the first time mentioned by Burton and Ingold. Since then, many other examples of loss of antioxidant activity or prooxidant activity have been illustrated and reviewed in the literature. Increasing oxygen partial pressure (PO2) and/or carotenoid concentration can convert a carotenoid from antioxidant to prooxidant. Thus, depending on the environment, the same molecule can exert either antioxidant or prooxidant activity. ... 

Reactive oxygen species play a central role in bile acid bioactivity. Hence anti-oxidant supplementation can correct some of the deleterious effects of acid suppression. 

The reduced activity of the n-6 fatty acid biosynthetic pathway in the diabetic nerve could decrease the availability of AA for prostanoid formation and this could have deleterious consequences on the nerve vasculature, with resultant adverse effects on nerve function. The depletion of AA could be exacerbated by a heightened level of reactive oxygen species (ROS), which react readily with the double bonds of polyunsaturated... 

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