Reactive oxygen species such as hydrogen peroxide, superoxide, peroxynitrite, or singlet oxygen causes damage to animal or plant cells and hence to the tissues and organs composed of those cells. This damage is medically termed as oxidative stress.

In simple words, it is an imbalance between antioxidants and free radicals. Free radicals prevail in this imbalance. 1-electron transfer in the mitochondrial electron transfer chain detrimentally produces Superoxide. Cytochrome P450(s), xanthine oxidase, and NADPH oxidases are rest of the enzymes with the capability to produce superoxide.

A wide variety of enzymes including oxidases and monoxygenases produces hydrogen peroxide; a role is played in cell signaling by oxygen species in Redox signaling.

Glutathione Peroxidase, Superoxide dismutase (SOD), and Catalase are the enzymes that are the best studied cellular antioxidants. Enzymatic antioxidants that are less well studied, but are of no less importance, are the Peroxiredoxins and the recently discovered sulfiredoxin. Aldehyde dehydrogenases, Paraxonase, and Glutathione-S transferases are the examples of other enzymes with antioxidant properties. However, antioxidant properties are not the primary characteristics of these enzymes.

Symptoms of Oxidative Stress:

They include;

• Tissue injury
• Hyperoxia
• Irradiation
  
  
• Neurodegenerative diseases (including Alzheimer’s disease, Lou Gehrig’s disease, Huntington’s disease, and Parkinson’s disease)

• Since oxidation of LDL in the endothelium is precursor to plaque formation, oxidative stress is considered to be linked to certain cardiovascular diseases
• Stroke
• Heart attack
• According to Harman’s free radical theory of aging, oxidative stress is also considered to contribute to the aging process. The evidence in mammals is contradictory despite the fact that in the model organism Drosophila melanogaster, there is somewhat strong evidence to support this idea.

Treatment Options:

• Antioxidants (vitamin E, C, and alpha-lipoic) NOTE: the use of vitamin E along without supplemented by other types of antioxidants can be harmful to high-risk group (e.g. smokers). You must never try to treat oxidative stress by yourself using drugs.
  
  
• Vegetables rich in vitamin E are beneficial to neurodegenerative diseases.

• AstraZeneca’s radical scavenging nitrone drug NXY-059 shows some efficacy in the treatment of stroke.