View source for Hydroxyl radical

== Introduction ==

The [[Hydroxyl radical|hydroxyl radical]] is a highly reactive [[Oxygen|oxygen]] species that is produced in biological systems. It is a type of [[Free radical|free radical]], which are atoms or molecules that have unpaired electrons. Because of its high reactivity, the hydroxyl radical can damage a wide range of molecules in cells, including [[DNA|DNA]], [[Protein|proteins]], and [[Lipid|lipids]].

[[Image:Detail-48641.jpg|thumb|center|A close-up image of a hydroxyl radical molecule.|class=only_on_mobile]]
[[Image:Detail-48642.jpg|thumb|center|A close-up image of a hydroxyl radical molecule.|class=only_on_desktop]]

== Formation ==

The hydroxyl radical is formed in the body through several mechanisms. One of the most common is through the [[Fenton reaction|Fenton reaction]], where [[Hydrogen peroxide|hydrogen peroxide]] (H2O2), a byproduct of normal metabolic processes, reacts with [[Iron|iron]] ions. This reaction produces the hydroxyl radical and other reactive oxygen species. Another common mechanism is through the [[Haber-Weiss reaction|Haber-Weiss reaction]], which involves the reaction of superoxide anion (O2-) with hydrogen peroxide.

== Role in Biological Systems ==

Despite its potential for causing damage, the hydroxyl radical plays an important role in several biological processes. For example, it is involved in the [[Immune system|immune response]], where it helps to kill bacteria and other pathogens. It is also involved in the regulation of [[Cell signaling|cell signaling]] pathways and the induction of [[Programmed cell death|programmed cell death]], or apoptosis.

== Damage to Biological Molecules ==

The hydroxyl radical is highly reactive and can cause extensive damage to biological molecules. It can react with DNA, causing mutations and DNA strand breaks. It can also react with proteins, leading to changes in protein structure and function. In addition, it can react with lipids, leading to lipid peroxidation and the disruption of cell membranes.

== Role in Disease ==

The hydroxyl radical has been implicated in a number of diseases. For example, it has been linked to [[Cancer|cancer]], where it can cause DNA mutations that lead to the development of cancerous cells. It has also been linked to [[Neurodegenerative disease|neurodegenerative diseases]], such as [[Alzheimer's disease|Alzheimer's]] and [[Parkinson's disease|Parkinson's]], where it can cause damage to neurons. In addition, it has been linked to [[Cardiovascular disease|cardiovascular diseases]], such as [[Atherosclerosis|atherosclerosis]], where it can contribute to the oxidation of low-density lipoproteins (LDL), a key step in the development of atherosclerosis.

== Detection and Measurement ==

Detecting and measuring the hydroxyl radical in biological systems is challenging due to its high reactivity and short lifespan. However, several methods have been developed to detect the hydroxyl radical, including [[Electron paramagnetic resonance|electron paramagnetic resonance]] (EPR) spectroscopy and the use of hydroxyl radical-specific fluorescent probes.

== See Also ==

* [[Reactive oxygen species]]
* [[Oxidative stress]]
* [[Antioxidant]]

[[Category:Chemistry]]
[[Category:Biology]]
[[Category:Medicine]]