18583-39-6Relevant academic research and scientific papers
Reaction between peroxynitrite and triphenylphosphonium-substituted arylboronic acid isomers: Identification of diagnostic marker products and biological implications
Sikora, Adam,Zielonka, Jacek,Adamus, Jan,Debski, Dawid,Dybala-Defratyka, Agnieszka,Michalowski, Bartosz,Joseph, Joy,Hartley, Richard C.,Murphy, Michael P.,Kalyanaraman, Balaraman
, p. 856 - 867 (2013)
Aromatic boronic acids react rapidly with peroxynitrite (ONOO-) to yield phenols as major products. This reaction was used to monitor ONOO - formation in cellular systems. Previously, we proposed that the reaction between ONOO- and arylboronates (PhB(OH)2) yields a phenolic product (major pathway) and a radical pair PhB(OH)2O ?-...?NO2 (minor pathway). [ Sikora, A. et al. (2011) Chem. Res. Toxicol.24, 687-697 ]. In this study, we investigated the influence of a bulky triphenylphosphonium (TPP) group on the reaction between ONOO- and mitochondria-targeted arylboronate isomers (o-, m-, and p-MitoPhB(OH)2). Results from the electron paramagnetic resonance (EPR) spin-trapping experiments unequivocally showed the presence of a phenyl radical intermediate from meta and para isomers, and not from the ortho isomer. The yield of o-MitoPhNO2 formed from the reaction between o-MitoPhB(OH)2 and ONOO- was not diminished by phenyl radical scavengers, suggesting a rapid fragmentation of the o-MitoPhB(OH) 2O?- radical anion with subsequent reaction of the resulting phenyl radical with ?NO2 in the solvent cage. The DFT quantum mechanical calculations showed that the energy barrier for the dissociation of the o-MitoPhB(OH)2O?- radical anion is significantly lower than that of m-MitoPhB(OH)2O ?- and p-MitoPhB(OH)2O?- radical anions. The nitrated product, o-MitoPhNO2, is not formed by the nitrogen dioxide radical generated by myeloperoxidase in the presence of the nitrite anion and hydrogen peroxide, indicating that this specific nitrated product may be used as a diagnostic marker product for ONOO-. Incubation of o-MitoPhB(OH)2 with RAW 264.7 macrophages activated to produce ONOO- yielded the corresponding phenol o-MitoPhOH as well as the diagnostic nitrated product, o-MitoPhNO2. We conclude that the ortho isomer probe reported here is most suitable for specific detection of ONOO- in biological systems.
Electrochemical Dimerization of Phenylpropenoids and the Surprising Antioxidant Activity of the Resultant Quinone Methide Dimers
Romero, Kevin J.,Galliher, Matthew S.,Raycroft, Mark A. R.,Chauvin, Jean-Philippe R.,Bosque, Irene,Pratt, Derek A.,Stephenson, Corey R. J.
supporting information, p. 17125 - 17129 (2018/12/04)
A simple method for the dimerization of phenylpropenoid derivatives is reported. It leverages electrochemical oxidation of p-unsaturated phenols to access the dimeric materials in a biomimetic fashion. The mild nature of the transformation provides excellent functional group tolerance, resulting in a unified approach for the synthesis of a range of natural products and related analogues with excellent regiocontrol. The operational simplicity of the method allows for greater efficiency in the synthesis of complex natural products. Interestingly, the quinone methide dimer intermediates are potent radical-trapping antioxidants; more so than the phenols from which they are derived—or transformed to—despite the fact that they do not possess a labile H-atom for transfer to the peroxyl radicals that propagate autoxidation.
