| An antioxidant is a molecule capable of
slowing or preventing the oxidation of other molecules. Oxidation is a
chemical reaction that transfers electrons from a substance to an oxidizing
agent. Oxidation reactions can produce free radicals, which start chain
reactions that damage cells. Antioxidants terminate these chain reactions by
removing free radical intermediates, and inhibit other oxidation reactions
by being oxidized themselves. As a result, antioxidants are often reducing
agents such as thiols or polyphenols. Although oxidation reactions are
crucial for life, they can also be damaging; hence, plants and animals
maintain complex systems of multiple types of antioxidants, such as
glutathione, vitamin C, and vitamin E as well as enzymes such as catalase,
superoxide dismutase and various peroxidases. |
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Space-filling model of the antioxidant metabolite
glutathione. The yellow sphere is the redox-active sulfur atom that
provides antioxidant activity, while the red, blue, white, and dark
grey spheres represent oxygen, nitrogen, hydrogen, and carbon atoms,
respectively. |
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| As oxidative stress might be an
important part of many human diseases, the use of antioxidants in
pharmacology is intensively studied, particularly as treatments for stroke
and neurodegenerative diseases. However, it is unknown whether oxidative
stress is the cause or the consequence of disease. Antioxidants are also
widely used as ingredients in dietary supplements in the hope of maintaining
health and preventing diseases such as cancer and coronary heart disease.
Although some studies have suggested antioxidant supplements have health
benefits, other large clinical trials did not detect any benefit for the
formulations tested, and excess supplementation may occasionally be harmful.
In addition to these uses in medicine, antioxidants have many industrial
uses, such as preservatives in food and cosmetics and preventing the
degradation of rubber and gasoline. |
