iscussing endogenous NO(?)/HNO interconversion aided by phenolic drugs and vitamins

MARIANA HAMER; SEBASTIAN A. SUÁREZ; NICOLAS NEUMAN; LUCIA ALVAREZ; MARTINA MUÑOZ; MACELO A MARTI; FABIO A DOCTOROVICH

INORGANIC CHEMISTRY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2015

0020-1669

The reduction of NO ? to HNO/NO − under biologically compatibleconditions has always been thought as unlikely, mostly because of the negativereduction potential: E°(NO ? ,H + /HNO) = −0.55 V vs NHE at physiological pH.Nonetheless, during the past decade, several works hinted at the possible NO-to-HNO conversion mediated by moderate biological reductants. Very recently, we haveshown that the reaction of NO ? with ascorbate and aromatic alcohols occurs througha proton-coupled nucleophilic attack (PCNA) of the alcohol to NO ? , yielding anintermediate RO−N(H)O ? species, which further decomposes to release HNO. Forthe present work, we decided to inspect whether other common biological aromaticalcohols obtained from foods, such as Vitamin E, or used as over-the-counter drugs,like aspirin, are able to undergo the reaction. The positive results suggest that theconversion of NO to HNO could occur far more commonly than previously expected. Taking these as the starting point, we setto review our and other groups? previous reports on the possible NO-to-HNO conversion mediated by biological compoundsincluding phenolic drugs and vitamins, as well as several thiol-bearing compounds. Analysis of revised data prompted us to askourselves the following key questions: What are the most likely physio/pathological conditions for NO ? -to-HNO conversion totake place? Which effects usually attributed to NO ? are indeed mediated by HNO? These inquiries are discussed in the context of2 decades of NO and HNO research.