Free radical

A free radical, or radical, is an atom or molecule with an unpaired electron. The radical is reactive and seeks another electron to pair.^[1]

Many free radicals, are (very reactive or) highly chemical reactive.

In biology

Free radicals are involved in the causes of damage associated with disease development. Examples are hydrogen peroxide, hypochlorite, nitric oxide and nitrogen dioxide.^[2]

The need for antioxidants in people's daily lives is becoming more critical with increased exposure to free radicals. Oxygen is highly reactive and can form free radicals; antioxidants can stabilize or deactivate oxygen free radicals before they attack cells. Pollution, cigarette smoke, drugs, illness, and stress can increase our exposure to oxygen free radicals.^[3]

References

↑ Rice-Evans, C. (1999). “Screening of phenolics and flavonoids for antioxidant activity”. In: Antioxidant Food Supplements in Human Health. Academic Press, p. 239–253.
↑ Afzal, M., Armstrong, D. (2002). “Fractionation of herbal medicine for identifying antioxidant activity”. In: Armstrong, D. (Ed.) Methods in Molecular Biology, vol. 186: Oxidative Stress Biomarkers and Antioxidant Protocols, Humana Press Inc.
↑ Percival, M. (1998). “Antioxidants”. Clinical Nutrition Insights 1/96 Rev. 10/98. http://acudoc.com/Antioxidants.PDF

This short article about science can be made longer. You can help Wikipedia by adding to it.

[Rice-Evans1-1] Rice-Evans, C. (1999). “Screening of phenolics and flavonoids for antioxidant activity”. In: Antioxidant Food Supplements in Human Health. Academic Press, p. 239–253.

[AfzalArmstrong1-2] Afzal, M., Armstrong, D. (2002). “Fractionation of herbal medicine for identifying antioxidant activity”. In: Armstrong, D. (Ed.) Methods in Molecular Biology, vol. 186: Oxidative Stress Biomarkers and Antioxidant Protocols, Humana Press Inc.

[3] Percival, M. (1998). “Antioxidants”. Clinical Nutrition Insights 1/96 Rev. 10/98. http://acudoc.com/Antioxidants.PDF

[1]

[2]

[3]