Antioxidants as therapies: can we improve on nature?

• Antioxidants have been relatively poor therapies.
• It is difficult to assess how well antioxidants work in vivo.
• Lack of efficacy is in part due to antioxidants not concentrating in the parts of the cell where they are needed.
• A way forward is to use medicinal chemistry to make more effective artificial antioxidants.

Although oxidative damage contributes to many pathologies the use of naturally occurring, small-molecule antioxidants as therapies for these disorders has not been successful. Here I discuss some of the reasons this may be so. Paramount among these are the difficulties in delivering enough of the antioxidant to the intracellular location required to decrease pathological oxidative damage and the challenge of assessing whether the intervention has actually decreased oxidative damage in the patient to a therapeutically useful extent. To develop effective antioxidant therapies the best strategy may be to create new chemical entities designed to detoxify a defined reactive oxygen species-dependent process that underlies a particular pathology, in the same way a conventional drug is designed to modulate a biochemical process, rather than applying antioxidants in an unfocused manner. In developing new antioxidants it will be useful to utilize endogenous processes to activate and recycle the molecules in parallel with the targeting of compounds to cells and organelles in ways that are not limited by the constraints that impair the distribution of endogenous antioxidants. In short, I suggest that the future development of antioxidant therapies should be viewed as an arm of drug development, utilizing focused approaches similar to those of medicinal chemistry and pharmacology, rather than as a branch of nutrition.

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