Biological origin of free radicals, and mechanisms of antioxidant protection

https://doi.org/10.1016/0009-2797(94)90033-7Get rights and content

Abstract

Reduced intermediates of molecular oxygen, such as superoxide and hydrogen peroxide, are ubiquitous inorganic products of normal aerobic metabolism. Certain cells, such as phagocytes, have evolved to use superoxide and hydrogen peroxide for purposeful chemistry beneficial to the host, but most cells require antioxidant protection against excessive production of these intermediates. Superoxide and hydrogen peroxide are themselves poorly reactive in aqueous solution, and unable to directly damage DNA, lipids and proteins. Excessive generation, however, of superoxide and hydrogen peroxide invariably accompanies molecular damage. Substantial evidence suggests that conversion of these poorly reactive intermediates of oxygen to highly reactive forms requires the participation of transition metal ions, particularly iron. Iron ions react with hydrogen peroxide (Fenton chemistry) to generate hydroxyl radicals that can damage all organic molecules.

References (18)

There are more references available in the full text version of this article.

Cited by (279)

  • Endosulfan causes oxidative stress in the liver and brain that involves inhibition of NADH dehydrogenase and altered antioxidant enzyme status in rat

    2022, Ecotoxicology and Environmental Safety
    Citation Excerpt :

    Xenobiotics alter this redox balance that results in cellular oxidative stress. The brain is endowed with relatively lower antioxidant enzymes such as catalase, and therefore, GPx plays the main role in quenching H2O2 and other peroxides, which otherwise will lead to the production of hydroxyl and peroxyl radicals in the presence of iron (Gutteridge, 1994; Bast and Bar, 1997). Hence, our study focussed on GPx activity in the brain.

  • Biomarkers of Oxidative Stress and Antioxidant Defense

    2022, Journal of Pharmaceutical and Biomedical Analysis
View all citing articles on Scopus
View full text