Drug antioxidant effect

An antioxidant may be defined as any substance that protects a given target against oxidative damage: hence the antioxidant properties of a compound will depend on the means used to assay it. Important targets of injury include not only lipids but also proteins and DNA. A wide range of natural and synthetic antioxidants has been proposed for therapeutic use. The logic behind their selection and potential problems in their use will be discussed. Another possibility is that drugs developed for other purposes may exert secondary antioxidant actions: possible examples include deprenyl, some Ca2+-antagonists and tamoxifen. By contrast, oxidation of certain drugs by free radical or by haem proteins (e.g. myoglobin, haemoglobin, myeloperoxidase, cytochrome c) can generate damaging free radicals that may contribute to drug side-effects; examples will be given from drugs used in the treatment of rheumatoid arthritis.