Interactions between fluoride and biological free radical reactions

• Published in: Fluoride Vol. 31; no. 1; pp. 43 - 45
• Main Authors: Rzeuski, R, Chlubek, D, Machoy, Z
• Format: Journal Article
• Language: English
• Published: 01.02.1998
• ISSN: 0015-4725

The term "free radical" means an atom, molecule or its fragment containing an unpaired electron. Oxygen free radicals include the superoxide radical (O sub(2) super(-)) and hydroxyl radical (OH) which, together with hydrogen peroxide (H sub(2)O sub(2)) and singlet oxygen ( super(1)O sub(2)), are jointly called reactive oxygen species. They originate in cells in the microsomal and mitochondrial electron transport chains, in chloroplasts in the process of photosynthesis, and in numerous enzymatic reactions as well as autoxidation of many compounds. Due to their high reactivity they may lead to chemical modification and impairment of the components of living cells (proteins, lipids, carbohydrates, nucleotides). Aerobic organisms mobilize mechanisms protecting them against the toxic action of oxygen radicals. Among these the most important involve enzymes, including superoxide dismutase (SOD), which catalyzes superoxide radical dismutation: O sub(2) super(-) + O sub(2) super(-) + 2H super(+) arrow right H sub(2)O sub(2) + O sub(2). The resulting hydrogen peroxide in turn is decomposed by the enzyme glutathione peroxidase (GSH-Px) and catalase (CAT). The basic activity of neutrophilic granulocytes - polymorphonuclear (PMN) leukocytes - is to defend the organism against infections. Fluoride is known to stimulate the so-called respiratory burst and the production of superoxide radicals of human and rabbit neutrophils as well as those of guinea pig. This process is associated with the activation of NADPH-dependent membranous oxidase appearing in these cells. Analogous effects are evoked by fluoride ions in leukemic cells (HL-60).