Carboxy-PTIO potassium salt

2-(4-Carboxyphenyl)-4,5-dihydro-4,4,5,5-tetramethyl-1H-imidazol-1-yloxy-3-oxide potassium salt, 2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt
Empirical Formula (Hill Notation):
CAS Number:
Molecular Weight:
MDL number:
PubChem Substance ID:
Pricing and availability is not currently available.

biological source

synthetic (organic)


≥98% (TLC)




> 270  °C


H2O: 100 mg/mL
DMSO: soluble (lit.)(lit.)
methanol: soluble (lit.)(lit.)

storage temp.


SMILES string




InChI key


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General description

2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO) is mainly considered as a scavenger of nitric oxide (NO).


Carboxy-PTIO potassium salt has been used to check the generation of hydroxyl radicals or nitric in reaction mixtures to examine the generation of nitric oxide in reaction mixture. It has also been added to neurons to analyse its effect on glucose/oxygen/serum deprivation (GOSD) condition(4)


10 mg in glass insert

Biochem/physiol Actions

Carboxy-PTIO can make a quick reaction with nitric oxide (NO) to produce nitrogen dioxide (NO2). It can be used to prevent hypotension and endotoxic shock, stimulated by lipopolysaccharide in- vivo. Carboxy-PTIO can also block in vitro vascular relaxation, stimulated by NO.
Reacts with nitric oxide to form carboxy-PTI derivatives which in turn inhibits nitric oxide synthase.

Personal Protective Equipment

dust mask type N95 (US),Eyeshields,Gloves


NONH for all modes of transport

WGK Germany


Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Certificate of Analysis
Certificate of Origin
M Yoshida et al.
Biochemical and biophysical research communications, 202(2), 923-930 (1994-07-29)
We recently found a new class of nitric oxide (NO) antidote, i.e., 2-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide derivatives (PTIOs). It has a potent inhibitory action against endothelium-derived relaxing factor. Here, we report the effect of a water-soluble carboxy derivative of PTIO (carboxy-PTIO) on endotoxin...
Interference of carboxy-PTIO with nitric oxide-and peroxynitrite-mediated reactions
Pfeiffer S, et al.
Free Radical Biology & Medicine, 22(5), 787-794 (1997)
Megumi Hada et al.
International journal of molecular sciences, 20(18) (2019-09-07)
Previously, we investigated the dose response for chromosomal aberration (CA) for exposures corresponding to less than one particle traversal per cell nucleus by high energy and charge (HZE) particles, and showed that the dose responses for simple exchanges for human...
Xinyi Zhu et al.
Applied and environmental microbiology, 85(3) (2018-11-28)
While both iron and nitric oxide (NO) are redox-active environmental signals shown to regulate biofilm development, their interaction and roles in regulating biofilms have not been fully elucidated. In this study, exposure of Pseudomonas aeruginosa biofilms to exogenous NO inhibited...
Nitric oxide scavenger carboxy-PTIO potentiates the inhibition of dopamine uptake by nitric oxide donors
Cao B J and Reith M EA
European Journal of Pharmacology, 448(1), 27-30 (2002)

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