Free radical

atom, molecule, or ion that has an unpaired valence electron; typically highly reactive

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

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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

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  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.
  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