69 research outputs found
Fifty Years of Diazeniumdiolate Research. From Laboratory Curiosity to Broad-Spectrum Biomedical Advances
Salmonella enterica biofilm-mediated dispersal by nitric oxide donors in association with cellulose nanocrystal hydrogels
Protected by extracellular polymers, microbes within biofilms are significantly more resistant to disinfectants. Current research has been instrumental in identifying nitric oxide donors and hydrogels as potential disinfectant additives. Nitric oxide (NO) donors are considered a very promising molecule as biofilm dispersal agents and hydrogels have recently attracted a lot of interest due to their biocompatible properties and ability to form stable thin films. When the NO donor MAHMA NONOate was dissolved in phosphate saline buffer, it was able to reduce the biomass of well-established biofilms up to 15% for at least 24Ā h of contact time. Encapsulation of MAHMA NONOate and molsidomine within a hydrogel composed of cellulose nanocrystals (CNC) has shown a synergistic effect in dispersing well-established biofilms: after 2Ā h of exposure, moderate but significant dispersion was measured. After 6Ā h of exposure, the number of cells transitioning from the biofilm to the planktonic state was up to 0.6 log higher when compared with non-treated biofilms. To further explore the transport processes of NO donors within hydrogels, we measured the nitric oxide flux from gels, at 25Ā°C for a composite of 0.1Ā ĀµM MAHMA NONOateāCNC. Nitric oxide diffuses up to 500Ā Āµm from the hydrogel surface, with flux decreasing according to Fickās law. 60% of NO was released from the hydrogel composite during the first 23Ā min. These data suggest that the combined treatments with nitric oxide donor and hydrogels may allow for new sustainable cleaning strategies
Understanding the Role of Hyponitrite in Nitric Oxide Reduction
Herein, we review the preparation and coordination chemistry of cis and trans isomers of hyponitrite, [N2O2](2-). Hyponitrite is known to bind to metals via a variety of bonding modes. In fact, at least eight different bonding modes have been observed, which is remarkable for such a simple ligand. More importantly, it is apparent that the cis isomer of hyponitrite is more reactive than the trans isomer because the barrier of N2O elimination from cis-hyponitrite is lower than that of trans-hyponitrite. This observation may have important mechanistic implications for both heterogeneous NOx reduction catalysts and NO reductase. However, our understanding of the hyponitrite ligand has been limited by the lack of a general route to this fragment, and most instances of its formation have been serendipitous
Aminolysis of an <i>N</i>āDiazeniumdiolated Amidine as an Approach to Diazeniumdiolated Ammonia
Recent theoretical studies have suggested
that the parent diazeniumdiolate
ion, H<sub>2</sub>NāNĀ(O)ī»NO<sup>ā</sup> (ādiazeniumdiolated
ammoniaā), might be stable enough to be isolated and that it
could potentially serve as a uniquely advantageous prodrug form of
bioactive nitroxyl (HNO). Here, we report on an attempt to isolate
its O<sup>2</sup>-benzylated derivative by aminolysis of the Cī»N
bond in PhCĀ(NH<sub>2</sub>)ī»NāNĀ(O)ī»NOBn. The
reaction proved remarkably sluggish in comparison to aminolysis of
unsubstituted benzamidine, and the desired product could not be isolated,
apparently because of base sensitivity of the NH<sub>2</sub> group.
Consistent with this interpretation, <i>O</i>-benzylhydroxylamine
and N<sub>2</sub>O were recovered from the reaction mixture in high
yields, along with <i><i>N,N</i></i>ā²-dibutylbenzamidine.
Theoretical calculations rationalize the observed slow aminolysis
by demonstrating that the diazeniumdiolate group greatly suppresses
the electrophilicity of the adjacent Cī»N carbon center, rendering
attack at that position endothermic. The data provide significant
insights into the challenges inherent to the pursuit of diazeniumdiolated
ammonia
Interaction of Nitric Oxide with Glutathione or Cysteine Generates Reactive Oxygen Species Causing DNA Single Strand Breaks
- ā¦