Oxidative Stress and Oxidants

By Dr Ananya Mandal, MD

Oxidative stress refers to a pathological state that arises from the damage caused by free radicals (collectively known of as reactive oxygen species, ROS) when they interact with molecules in the body.

These free radicals can damage any component of the cell such as the DNA, the proteins and the lipids and give rise to cancer and various other disease states such as heart disease and neurodegenerative disorders.

Free radicals

The oxygen molecule is highly reactive and quite toxic. Examples of free radicals include:

  • Singlet oxygen
  • Perhydroxyl
  • Hydroxyl radical
  • Superoxide anion
  • Nitric oxide

Free radicals are essentially molecules that contain an unpaired electron. This means they are highly unstable and seek out and capture electrons from molecules in healthy cells to stabilize themselves. This leaves the molecules they stole an electron from destabilized and those molecules then need to seek out stabilization, leading to a chain of thousands of free radical reactions.

Antioxidants counteract the actions of free radicals by donating an electron without destabilizing their structure. Through this stabilization, antioxidants prevent further damage to healthy cells.

Oxidative stress occurs when free radicals are too numerous for antioxidants to adequately neutralize. Environmental pollutants, toxins, medications, infections, poor diet and radiation are all factors that contribute to the likelihood of this free radical/antioxidant imbalance.

Reviewed by , BSc

Sources

  1. http://web.mst.edu/~nercal/documents/chem464/lectures/lec01_freeradicals.pdf
  2. http://www.med.or.jp/english/pdf/2002_07/271_276.pdf
  3. http://www.jmas.in/2ndissue/JMAS%202nd%20issue%20PDF%20for%20Print/Free%20radicals,%20oxidative%20stress%20and%20importance%20of%20antioxidants%20in%20human%20health.pdf
  4. http://www.frag-chile.cl/documentos/H_Sies_Free_Radical_School_Chile-2009.pdf
  5. http://www.ncbi.nlm.nih.gov/pmc/articles/pmid/8367443/

Further Reading

Last Updated: Jan 14, 2014

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