semiquinone

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sem·i·quin·one

(sem'ē-kwin'ōn),
A free radical resulting from the removal of one hydrogen atom with its electron during the process of dehydrogenation of a hydroquinone to quinone or similar compound (for example, flavin mononucleotide).
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it was also observed that semiquinone and quinone radicals are involved in damage of DNA structure by discussed xenobiotics.
4benzoqui-none and tetrachloro-1,2-benzoquinone by intermediate steps with formation of respective semiquinone radicals.
Although a link between free radicals in these samples and health impacts was suspected, their potential health impacts were not recognized because they were thought to be "inaccessible to cells and too stable to play any part in carcinogenesis" until the publication of a series of papers by Pryor and colleagues demonstrating the viability of catalytic cycles involving semiquinone radicals (Pryor and Squadrito 1995; Pryor et al.
Semiquinone radicals are known to undergo redox cycling to produce biologically damaging superoxide and hydroxyl radicals.
Hence, as it follows from our data, ubisemiquinone radicals were much less susceptible to oxygen than radicals of other semiquinones when studied within a CL bilayer, which modeled the mitochondrial environment of respiratory complexes.
In case of semiquinone, this will partly regenerate the initial quinol molecule via disproportionation:
For instance, a semiquinone radical can be oxidized by molecular oxygen yielding a superoxide anion and a fully oxidized quinone molecule as products:
Generally, any interaction that would selectively stabilize the polar semiquinone molecule should increase the respective [E.
that not stored in vesicles and due to VMAT inhibition) enhance both enzymatic and nonenzymatic degradation of DA, leading to an increase in the formation of reactive DA metabolites (LaVoie and Hastings 1999), including quinones and semiquinones shown to inhibit DAP function (Berman et al.
In this context, phenolics, and especially 1,2- and 1,4-diphenols, which are ubiquitously present in the olive oil, can easily undergo (auto)oxidation producing semiquinone or quinone radicals, or they can become radicals themselves during the reaction with free radicals [8, 23], thereby contributing to the overall oxidant/electrophilic load.