In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons. These unpaired electrons are usually highly reactive, so radicals are likely to take part in chemical reactions.
Reactive oxygen species (ROS) include oxygen ions, free radicals and peroxides both inorganic and organic. They are generally very small molecules and are highly reactive due to the presence of unpaired valence shell electrons. ROSs form as a natural byproduct of the normal metabolism of oxygen and have important roles in cell signaling.
The source of ROS is the oxidative metabolism, mainly mitochondrial. During energy transduction, a small number of electrons accidentally “leak” to oxygen prematurely, forming damaging radicals, ROS (reactive oxygen species). The key reactive species are superoxide radical (O 2 -) and hydrogen peroxide (H 2 O 2 ); an important role is also played by hydroxil radical (HO°). These partially reduced species, as it is dictated by their higher reduction potentials, can oxidize the biomolecules with which oxygen itself reacts poorly. The strong univalent oxidant is hydroxil radical (HO°), which reacts at virtually diffusion-limited rates with most biomolecules.
All of these species are oxidants with the exception of superoxide anion (O 2 -) which is a strong reducing agent
(O 2 - + Fe +++ --> O 2 + Fe ++ )
Additional sources of ROS are:
- Cyt P450
- Oxidases (NADPH Oxidase, Xanthine-Ox. Glucose Ox., Cholesterol Ox.)
Antioxidants tentative list
- levels of intracellular glutathione
- glutathione peroxidase
- oxygen reactive metabolites
- antioxidant biologic potential
- Carr unit (oxidizing reserve of plasma)?
- Dove effettuarli?
- Quale è il modo migliore di reintegrare il glutatione?
Chronic elevation of plasma thioredoxin: inhibition of chemotaxis and curtailment of life expectancy in AIDS.