Related Experiment Video
Updated: Jun 2, 2026
09:23
A Protocol for Detecting and Scavenging Gas-phase Free Radicals in Mainstream Cigarette Smoke
Published on: January 2, 2012
Endogenous antioxidants and radical scavengers
Angela Maria Rizzo1, Patrizia Berselli, Stefania Zava
1Department of Molecular Sciences Applied to Biosystems, DISMAB, University of Milan, Italy. Institute of General Physiology and Biochemistry,
Advances in Experimental Medicine and Biology
|April 28, 2011
Summary
Oxidative stress from reactive species (RS) causes cellular damage and aging. This chapter reviews endogenous antioxidants like Glutathione and Melatonin that combat these harmful effects.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Biology
Background:
- Organisms face constant exposure to endogenous and exogenous oxidants, leading to biomolecule modification and cellular damage.
- Oxidative stress, driven by free radicals, plays a significant role in tissue damage and the aging process.
- Reactive species (RS), including reactive oxygen species (ROS) and reactive nitrogen species (RNS), are key contributors to oxidative stress.
Purpose of the Study:
- To critically discuss endogenous antioxidant molecules that protect against oxidative damage.
- To highlight the imbalance between reactive species production and antioxidant defenses.
- To provide a comprehensive overview of key endogenous antioxidants.
Main Methods:
- Literature review focusing on endogenous antioxidant molecules.
- Critical analysis of scientific data regarding antioxidant functions.
- Synthesis of information on specific antioxidant compounds.
Main Results:
- Identified key endogenous antioxidants: Glutathione, Alpha-lipoic acid, Coenzyme Q, Ferritin, Uric acid, Bilirubin, Metallothioneine, L-carnitine, and Melatonin.
- Detailed the mechanisms by which these molecules counteract reactive species.
- Emphasized the importance of antioxidant defense systems in preventing cellular damage.
Conclusions:
- Endogenous antioxidants are crucial for mitigating oxidative stress and its detrimental effects.
- Maintaining a balance between reactive species and antioxidant defenses is vital for cellular health.
- Understanding these endogenous molecules provides insight into aging and disease prevention.
More Related Videos
Related Concept Videos
01:20Radical Autoxidation
The oxidation of an organic compound in the presence of air or oxygen is called autoxidation. For example, cumene reacts with oxygen to form hydroperoxide. Autoxidation involves initiation, propagation, and termination steps. Many organic compounds are susceptible to autoxidation—especially ethers in the presence of oxygen, which form hydroperoxides. Even though this reaction is slow, old ether bottles contain small amounts of peroxide, which leads to laboratory explosions during ether...
01:17Oxidation of Phenols to Quinones
In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The electron-donating hydroxyl group enhances the reactivity of the aromatic ring, enabling oxidation of the ring even in the absence of an α hydrogen.
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
01:11Radical Reactivity: Overview
Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired molecule. These three...
01:10Radical Reactivity: Steric Effects
The presence of electron-donating, electron-withdrawing, or conjugating groups adjacent to a radical center, imparts electronic stabilization to the radicals. Examples of such electronically-stabilized radicals are triphenylmethyl, tetramethylpiperidine‐N‐oxide, and 2,2‐diphenyl‐1‐picrylhydrazyl. These radicals are remarkably stable and are known as persistent radicals. Some of the persistent radicals can even be isolated and purified.
Along with electronic factors, steric factors also account...
Along with electronic factors, steric factors also account...
01:33Radical Reactivity: Intramolecular vs Intermolecular
Radical reactions can occur either intermolecularly or intramolecularly. In an intermolecular radical reaction, a nucleophilic radical adds to an electrophilic alkene or vice versa. In such reactions, the radical and generally the alkene, which is also called the radical trap, are two different molecules. Additionally, for such intermolecular reactions to occur, the radical trap must be active, present in an excess concentration, and the radical starting material must have a weak carbon–halogen...
01:16Radical Reactivity: Nucleophilic Radicals
Radicals adjacent to electron-donating groups are called nucleophilic radicals. These radicals readily react with electrophilic alkenes. The SOMO–LUMO interactions are the driving force for the reaction, where the high-energy SOMO of the electron-rich, nucleophilic radicals interacts with the low-energy LUMO of the electron-deficient, electrophilic alkenes. Such SOMO–LUMO interactions are the basis of reactive radical traps, affecting the selectivity in radical reactions. For instance, consider...