 The metal ion in this reaction can be reduced, oxidized, and then re-reduced, in a process called redox cycling that can generate reactive oxygen species.The relative importance of the antioxidant and pro-oxidant activities of antioxidant vitamins are an area of current research, but vitamin C, for example, appears to have a mostly antioxidant action in the body.However, less data is available for other dietary antioxidants, such as polyphenol antioxidants, zinc, and vitamin E.

Several important anticancer agents both bind to DNA and generate reactive oxygen species.