title: Free radicals in physiology and pathology.
abstract: Free radicals are molecules with odd number of electrons and a high instability. Free radicals, which can occur in both organic (i.e., quinones) and inorganic molecules (i.e., O2-), are very reactive and their reactions are critical for the normal activity of a wide spectrum of biologic processes. They are also produced in the catalytic action of a variety of cellular enzymes and electron transport processes and are implicated in a number of physiologic and pathologic processes. Organisms can be exposed to free radicals in many ways other than through the processes of normal metabolism. Irradiation of organisms with electromagnetic radiation generates primary radicals (e-aq, OH., and H.), which can then undergo secondary reactions with dissolved O2 or with cellular solutes. In addition, a wide variety of environmental agents (drugs capable of redox cycling, and xenobiotics that can form free radical metabolites) including the aging process cause free radical damage to cells. This review deals with the reactions they can undergo and discusses the free radicals related to toxicology.
authors.affiliation: Department of Experimental Medicine and Oncology, University or Torino.
authors.forename: M U
authors.initials: MU
authors.lastname: Dianzani
mesh_terms: D000447:Aldehydes / Q000378:metabolism / Q000494:pharmacology / Q000633:toxicity; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002252:Carbon Tetrachloride Poisoning / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D004578:Electron Spin Resonance Spectroscopy; D005227:Fatty Acids / Q000378:metabolism; D016166:Free Radical Scavengers; D005609:Free Radicals / Q000737:chemistry / Q000633:toxicity; D015227:Lipid Peroxidation; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism; D015388:Organelles / Q000187:drug effects; D010084:Oxidation-Reduction
chemical_list: D000447:Aldehydes; D000975:Antioxidants; D005227:Fatty Acids; D016166:Free Radical Scavengers; D005609:Free Radicals; D008563:Membrane Lipids; C027576:4-hydroxy-2-nonenal