Reactive Oxygen Species

Definition

Reactive oxygen species, often abbreviated ROS, are oxygen-containing molecules that are more chemically reactive than ordinary oxygen. Examples include superoxide, hydrogen peroxide, and hydroxyl radicals. ROS are produced during normal metabolism, especially in mitochondria, and can also arise from immune activity, inflammation, radiation, toxins, and other cellular stresses. [1] [2] [3]

Why It Matters in Ageing Research

Reactive oxygen species matter because they can both damage cellular components and act as signalling molecules. At excessive levels, ROS can contribute to oxidative stress by damaging DNA, proteins, lipids, and mitochondria. At controlled levels, however, ROS also participate in normal cell signalling, adaptation to stress, immune defence, and exercise-related responses. Modern ageing research therefore treats ROS as part of a regulated redox system rather than simply as harmful waste products. [2] [4] [5]

Common Confusion

• ROS are not always harmful; they also serve important signalling and defence roles.
• Oxidative stress is not the same as ROS production; it refers to an imbalance between oxidants and protective systems.
• Antioxidant supplements do not automatically improve ageing outcomes just because ROS can cause damage.

Related Reading

• Oxidative Stress
• Mitochondrial Dysfunction
• Mitophagy

References

1. Halliwell, B. (2006). Reactive species and antioxidants. Redox biology is a fundamental theme of aerobic life. https://pubmed.ncbi.nlm.nih.gov/16500660/
2. Finkel, T. (2011). Signal transduction by reactive oxygen species. https://pubmed.ncbi.nlm.nih.gov/21954935/
3. Murphy, M. P. (2009). How mitochondria produce reactive oxygen species. https://pubmed.ncbi.nlm.nih.gov/19076483/
4. Sena, L. A., & Chandel, N. S. (2012). Physiological roles of mitochondrial reactive oxygen species. https://pubmed.ncbi.nlm.nih.gov/23131636/
5. Sies, H., Berndt, C., & Jones, D. P. (2017). Oxidative stress. https://pubmed.ncbi.nlm.nih.gov/28441057/