PMID- 23122928
OWN - NLM
STAT- MEDLINE
DCOM- 20130530
LR  - 20171116
IS  - 1873-3344 (Electronic)
IS  - 0162-0134 (Linking)
VI  - 118
DP  - 2013 Jan
TI  - The use of cyclic nitroxide radicals as HNO scavengers.
PG  - 155-61
LID - S0162-0134(12)00321-2 [pii]
LID - 10.1016/j.jinorgbio.2012.10.002 [doi]
AB  - Reduction of cyclic stable nitroxides (RNO) by HNO to the respective 
      hydroxylamines (RNO-H) has been demonstrated using EPR spectrometry. HNO shows 
      low reactivity toward piperidine, pyrrolidine and nitronyl nitroxides with rate 
      constants below 1.4 x 10(5)M(-1)s(-1) at pH 7.0, despite the high driving force 
      for these reactions. The rate constants can be predicted assuming that the 
      reactions take place via a concerted proton-electron transfer pathway and 
      significantly low self-exchange rate constants for HNO/NO and RNO-H/RNO. NO does 
      not react with piperidine and pyrrolidine nitroxides, but does add to HNO forming 
      the highly oxidizing and moderately reducing hyponitrite radicals. In this work, 
      the radicals are produced by pulse radiolysis and the rate constants of their 
      reactions with 2,2,6,6,-tetramethylpiperidine-1-oxyl (TEMPO), 
      4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl (TEMPOL) and 3-carbamoyl-PROXYL 
      have been determined at pH 6.8 to be (2.4 +/- 0.2)x 10(6), (9.8 +/- 0.2)x 10(5), (5.9 
      +/- 0.5)x 10(5)M(-1)s(-1), respectively. This low reactivity implies that NO 
      competes efficiently with these nitroxides for the hyponitrite radical. The 
      ability of TEMPOL and 
      2-(4-carboxyphenyl)-4,4,5,5,-tetramethyl-imidazoline-1-oxyl-3-oxide (C-PTIO) to 
      oxidize HNO and their different reactivity toward NO are used to quantify HNO 
      formed via acetohydroxamic acid oxidation. The extent of TEMPOL or C-PTIO 
      reduction was similar to the yield of HNO formed upon oxidation by ()OH under 
      anoxia, but not by the metmyoglobin and H(2)O(2) reaction system where both 
      nitroxides catalytically facilitate H(2)O(2) depletion and nitrite accumulation. 
      In this system the conversion of C-PTIO into 
      2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl (C-PTI) is a minor 
      reaction, which does not provide any mechanistic insight.
CI  - Copyright (c) 2012 Elsevier Inc. All rights reserved.
FAU - Samuni, Yuval
AU  - Samuni Y
AD  - Oral and Maxillofacial Surgery, The Barzilai Medical Center, Ashkelon, Israel.
FAU - Samuni, Uri
AU  - Samuni U
FAU - Goldstein, Sara
AU  - Goldstein S
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20121012
PL  - United States
TA  - J Inorg Biochem
JT  - Journal of inorganic biochemistry
JID - 7905788
RN  - 0 (Benzoates)
RN  - 0 (Cyclic N-Oxides)
RN  - 0 (Free Radical Scavengers)
RN  - 0 (Free Radicals)
RN  - 0 (Hydroxamic Acids)
RN  - 0 (Hydroxylamines)
RN  - 0 (Imidazoles)
RN  - 0 (Nitrites)
RN  - 0 (Nitrogen Oxides)
RN  - 0 (Oxidants)
RN  - 12772-23-5 (Metmyoglobin)
RN  - 14448-38-5 (hyponitrite)
RN  - 145757-47-7 
      (1,3-dihydroxy-4,4,5,5-tetramethyl-2-(4-carboxyphenyl)tetrahydroimidazole)
RN  - 2FP81O2L9Z (Hydroxylamine)
RN  - 4RZ82L2GY5 (acetohydroxamic acid)
RN  - BBX060AN9V (Hydrogen Peroxide)
RN  - GFQ4MMS07W (nitroxyl)
RN  - V55XB6IT82 (TEMPOL-H)
RN  - VQN7359ICQ (TEMPO)
SB  - IM
MH  - Benzoates/chemistry
MH  - Cyclic N-Oxides/*chemistry
MH  - Electron Spin Resonance Spectroscopy
MH  - Free Radical Scavengers/*chemistry
MH  - Free Radicals/*chemistry
MH  - Hydrogen Peroxide/chemistry
MH  - Hydroxamic Acids/chemistry
MH  - Hydroxylamine/*chemistry
MH  - Hydroxylamines/chemistry
MH  - Imidazoles/chemistry
MH  - Kinetics
MH  - Metmyoglobin/chemistry
MH  - Models, Chemical
MH  - Nitrites/chemistry
MH  - Nitrogen Oxides/*chemistry
MH  - Oxidants/chemistry
MH  - Oxidation-Reduction
MH  - Pulse Radiolysis
EDAT- 2012/11/06 06:00
MHDA- 2013/06/01 06:00
CRDT- 2012/11/06 06:00
PHST- 2012/05/21 00:00 [received]
PHST- 2012/09/11 00:00 [revised]
PHST- 2012/10/04 00:00 [accepted]
PHST- 2012/11/06 06:00 [entrez]
PHST- 2012/11/06 06:00 [pubmed]
PHST- 2013/06/01 06:00 [medline]
AID - S0162-0134(12)00321-2 [pii]
AID - 10.1016/j.jinorgbio.2012.10.002 [doi]
PST - ppublish
SO  - J Inorg Biochem. 2013 Jan;118:155-61. doi: 10.1016/j.jinorgbio.2012.10.002. Epub 
      2012 Oct 12.