free radical


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radical

 [rad´ĭ-kal]
1. thorough or sweeping; directed to the cause or root of a morbid process.
2. a group of atoms that enters into and goes out of chemical combination without change and that forms one of the fundamental constituents of a molecule.
color radical chromophore.
free radical a radical that carries an unpaired electron; such radicals are extremely reactive, with a very short half-life.
oxygen radical a toxic metabolite of oxygen, such as superoxide or singlet oxygen, capable of damaging microorganisms and normal tissues.

free rad·i·cal

a radical in its (usually transient) uncombined state; an atom or atom group carrying an unpaired electron and no charge; e.g., hydroxyl and methyl
Free radicals may be involved as short-lived, highly active intermediates in various reactions in living tissue, notably in photosynthesis. The free radical nitric oxide, NO·, plays an important role in vasodilation.
Synonym(s): radical (4)

Free radicals are formed naturally as products of metabolic processes and can also be introduced from outside the body through smoking, inhaling environmental pollutants, or exposure to ultraviolet radiation. They interact readily with nearby molecules and may cause cellular damage, including genetic alterations. It has been theorized that they are involved in degenerative disorders such as Alzheimer dementia and parkinsonism, in plaque formation in atherosclerosis, and in cancer. Natural enzymes such as superoxide dismutase and peroxidase are thought to counteract free radicals, and there is evidence that many nutrients, including vitamins C and E and beta-carotene, also exert an antioxidant effect. see also antioxidant.

free radical

n.
An atom or group of atoms that has at least one unpaired electron and is therefore unstable and highly reactive. In animal tissues, free radicals can damage cells and are believed to accelerate the progression of cancer, cardiovascular disease, and age-related diseases.

free radical

Physiology
Any of a family of highly reactive molecules containing an unpaired electron in the outer orbital (e.g., the excited variants of O2). Free radicals cause random damage to structural proteins, enzymes, macromolecules and DNA; they play major roles in inflammation, hyperoxidation, post-ischaemic tissue damage, infarction and possibly also in carcinogenesis and tissue damage induced by organ transplantation. Free radical production is increased by cigarette smoking, radiation, UV light and chemical pollutants.

free radical

Physiology Any of a family of highly reactive molecules containing an unpaired electron in the outer orbital–eg, the excited variants of O2; FRs cause random damage to structural proteins, enzymes, macromolecules, DNA, playing major roles in inflammation, hyperoxidation, post-ischemic tissue damage, infarction, possibly also CA and tissue damage in transplants. See Antioxidants, Free radical scavenger, Free radical theory Vox populi Freed radical A paroled political polemicist.

free rad·i·cal

(frē rad'i-kăl)
A radical in its (usually transient) uncombined state; an atom or atom group carrying an unpaired electron and no charge. Free radicals may be involved as short-lived, highly active intermediates in various reactions in living tissue, notably in photosynthesis. The free radical nitric oxide, NO·, plays an important role in vasodilation.
Synonym(s): radical (4) .

free radical

an atom which has been ionized by radiation and from which electrons have been ejected as a result, leaving one or more unpaired electrons; such atoms react with other molecules e.g. DNA, and may cause damage or mutation.

Free radical

An unstable molecule that causes oxidative damage by stealing electrons from surrounding molecules, thereby disrupting activity in the body's cells.
Mentioned in: Smoking

free rad·i·cal

(frē rad'i-kăl)
A radical in its (usually transient) uncombined state; an atom or atom group carrying an unpaired electron and no charge.
Synonym(s): radical (4) .
References in periodicals archive ?
Free radicals are unstable molecules that can cause damage to healthy cells and have been linked to conditions like inflammation, heart disease, and cancer.
DPPH free radicals scavenging assay: For this attempt of DPPH (1, 1-diphenyle-2-picrylehydrazyl) scavenging activity, the technique of Gymfi et al., (1999) with some modifications.
"The most important aim of this research was to better understand the development of stable free radicals during the roasting process and the possible influence exerted by developed radicals on the well-documented coffee antioxidant properties.
The free radicals had no impact on the pups' immune responses or their ability to fight the flu.
The onslaught from internal free radicals caused by infections, illness, obesity, accidents and surgery, plus external free radicals from smoking and exposing our skins to bright sunlight, means the body is unable to keep pace.
(b) Optimal conditions of thermal sterilization for bismuth subgallate with the lowest free radical formation are temperature 170[degrees] C and time of heating 60 minutes.
If your body is under siege from free radicals, your skin will reflect the struggle.
Recently increasing interest is seen in the role of free radicals and oxidative damage in a variety of pathophysiological processes.
A.: Free radicals are a product of a chemical reaction that is generated any time a person breathes oxygen.
At the time, Harman's idea did not generate much interest, but it wasn't long before the scientific world began to vigorously debate the existence of his rogue "free radicals."
Now researchers report in the August 2005 Journal of Clinical Investigation that even before the immune system cranks up, NADPH oxidases in pollen itself generate a type of free radical known as reactive oxygen species (ROS), which interfere with cell signaling pathways and cause the immune system to overreact.
Rohm and Haas Company has received a patent for a method for making a coating having a low gloss finish comprised of disposing a layer of a coating powder onto a substrate, wherein the coating powder comprises one or more than one cationic curable resin chosen from aromatic epoxides, polyglycidyl compounds having an aromatic structure, epoxy novolac resins, epoxy cresol resins, vinyl ethers, oxetanes, oxolanes, cyclic acetals, thiiranes, thiotanes, and combinations thereof; one or more cationic photoinitiator; one or more free radical curable resin; and one or more free radical photoinitiator.