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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 ...
This radical adds O 2 to give hydroperoxyl radical (red). In a propagation step, this hydroperoxyl radical abstracts an H + atom from a new diene, generating a new pentadienyl radical and a hydroperoxide (blue). The chemical reaction of lipid peroxidation consists of three phases: initiation, propagation, and termination. [4]
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 fact that oxygen changes the radiation chemistry might be one reason why oxygenated tissues are more sensitive to irradiation than the deoxygenated tissue at the center of a tumor. The free radicals, such as the hydroxyl radical, chemically modify biomolecules such as DNA, leading to damage such as breaks in the DNA strands. Some substances ...
Skeletal formulae of 1-hydroxy-2()-pyridinethione and its tautomer. The hydroxyl radical, • HO, is the neutral form of the hydroxide ion (HO –).Hydroxyl radicals are highly reactive and consequently short-lived; however, they form an important part of radical chemistry.
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]