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Free radical toxicity induced by xenobiotics and the subsequent detoxification by cellular enzymes (termination). Effects of ROS on cell metabolism are well documented in a variety of species. [ 19 ] These include not only roles in apoptosis (programmed cell death) but also positive effects such as the induction of host defence [ 36 ] [ 37 ...
The free radical theory of aging states that organisms age because cells accumulate free radical damage over time. [1] A free radical is any atom or molecule that has a single unpaired electron in an outer shell. [2] While a few free radicals such as melanin are not chemically reactive, most biologically relevant free radicals are highly ...
In alternative fashion, nitrite anions on sun-exposed skin may be photolyzed to free nitric oxide radicals by UVA in sunlight. [19] This mechanism may elicit significant changes to the systemic blood circulation in humans and be exploited for therapeutic purposes. [20] Nasal breathing also produces nitric oxide within the body. [21] [22] [23] [24]
The electrical discharges initiated by the ionization events by the particles result in plasma populated by large amount of free radicals. The highly reactive free radicals can recombine back to original molecules, or initiate a chain of free-radical polymerization reactions with other molecules, yielding compounds with increasing molecular ...
In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron. [1] [2] With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes.
The lipid hydroperoxyl radical (LOO•) can also undergo a variety of reactions to produce new radicals. [citation needed] The additional lipid radical (L•) continues the chain reaction, whilst the lipid hydroperoxide (LOOH) is the primary end product. [6] The formation of lipid radicals is sensitive to the kinetic isotope effect.
The hydroxyl radical can damage virtually all types of macromolecules: carbohydrates, nucleic acids , lipids (lipid peroxidation) and amino acids (e.g. conversion of Phe to m-Tyrosine and o-Tyrosine). The hydroxyl radical has a very short in vivo half-life of approximately 10 −9 seconds and a high reactivity. [5]
Oxidative stress mechanisms in tissue injury. Free radical toxicity induced by xenobiotics and the subsequent detoxification by cellular enzymes (termination).. Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. [1]