Electrochemical analysis of the kinetics of nitric oxide release from two diazeniumdiolates in buffered aqueous solutions

We have investigated in this work the kinetics of NO-release from two commercially available and commonly used diazeniumdiolates (so-called NONOates), namely diethylammonium (Z)-1-(N,N-diethylamino)-diazen-1-ium-1,2-diolate (DEA-NONOate) and (Z)-1-[N-(2-aminoepropyl)-N-(2-ammoniopropyl)amino]-diazen-1-ium-1,2-diolate (PAPA-NONOate) by electrochemical measurements. This choice was driven by the distinctive half-life of each compound (2–20 min at 37 °C for DEA- and PAPA-NONOate, respectively) that allow covering a relatively wide range of rate of NO-release. The release of NO from NONOate decomposition was followed using a home-made NO-sensitive electrochemical sensor. The electrochemical features of the starting NONOates and of the by-products of the fully decomposed molecules were also examined. Also, the electrochemical experimental results obtained under aerobic atmosphere were numerically fitted to model the production of NO and its degradation through its oxidation by molecular oxygen. All these information gathered together allows in predicting the real amount of NO released under real aerobic conditions.