Peroxynitrite reduction potential

At present, new developments challenge previous ideas concerning the role of nitric oxide in oxidative processes. The capacity of nitric oxide to oxidize substrates by a one-electron transfer mechanism was supported by the suggestion that its reduction potential is positive and relatively high. However, recent determinations based on the combination of quantum mechanical calculations, cyclic voltammetry, and chemical experiments suggest that °(NO/ NO-) = —0.8 0.2 V [56]. This new value of the NO reduction potential apparently denies the possibility for NO to react as a one-electron oxidant with biomolecules. However, it should be noted that such reactions are described in several studies. Thus, Sharpe and Cooper [57] showed that nitric oxide oxidized ferrocytochrome c to ferricytochrome c to form nitroxyl anion. These authors also proposed that the nitroxyl anion formed subsequently reacted with dioxygen, yielding peroxynitrite. If it is true, then Reactions (24) and (25) may represent a new pathway of peroxynitrite formation in mitochondria without the participation of superoxide. 

Reductions Potentials at pH 7.0 of Nitric Oxide, Peroxynitrite, and Other Secondary Species Derived from Peroxynitrite"... 

The reaction of peroxynitrite (ONOO ) was also investigated with a series of para-substituted phenols in phosphate buffer solutions . The corresponding 2-nitro derivative and the 4-substituted catechol were the major products. The reaction exhibits good correlation with Hammett ap+ and half-wave reduction potentials, suggesting a... 

In contrast, CO " radicals, with a reduction potential of 1.59V versus NHE, selectively oxidize biomolecules by one-electron abstraction mechanisms [23]. It has been suggested that in vivo, CO " radicals are formed via homolysis of nitro-soperoxycarbonate derived from the combination (feg = 2.9 x 1()4 M"1 s"1) [24] of carbon dioxide and peroxynitrite ... 

The reaction of peroxynitrite (ONOO ) with a series of phenols (8) in aqueous phosphate buffer or acetonitrile solutions has been examined. A good correlation of substituent effects on competitive reactions with the reduction potential of the radicals... 

The practical significance of the reaction depicted in Scheme 7.43 consists of the development of novel antioxidants carrying chalcogen atoms. Divalent organochalcogen compounds react readily with many types of oxidants (peroxide, peroxyl radicals, peroxynitrite, singlet oxygen, and ozone). The tetravalent organylchalcogenides formed are reduced by many mild reductants. Therefore, compounds of this sort have the potential to act as catalytic antioxidants. 

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