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Synthesis and evaluation of DMPO-type spin traps
1Institute for Life Support Technology, Yamagata Technopolis Foundation, Japan.
Free Radical Research
|July 1, 1995
Summary
New spin traps, 4MDMPO, 4PDMPO, and 4HMDMPO, were synthesized and evaluated against DMPO. These derivatives show comparable performance in trapping superoxide radicals but exhibit distinct electron spin resonance spectra when trapping hydroxyl radicals.
Area of Science:
- Organic Chemistry
- Analytical Chemistry
- Spectroscopy
Background:
- Dimethyl-1-pyrroline N-oxide (DMPO) is a widely used spin trap for detecting free radicals.
- Modifications to the DMPO structure can alter its physical properties and spin-trapping capabilities.
- Understanding these modifications is crucial for optimizing radical detection methods.
Purpose of the Study:
- To synthesize and characterize novel DMPO derivatives: 4,5,5-Trimethyl-1-pyrolline N-oxide (4MDMPO), 5,5-dimethyl-4-phenyl-1-pyrolline N-oxide (4PDMPO), and 5,5-dimethyl-4-hydroxymethyl-1-pyrolline N-oxide (4HMDMPO).
- To compare the spin-trapping abilities and physical properties of these new derivatives with DMPO.
- To investigate the electron spin resonance (ESR) spectra of spin adducts formed with these compounds.
Main Methods:
- Synthesis of 4MDMPO and 4PDMPO using the Bonnett method.
- Synthesis of 4HMDMPO from 2(5H)-furanone.
- Determination of melting points and partition coefficients (hydrophilicity) in a 1-octanol--water system.
- Spin trapping of various radicals (O2-., HO., .CH3, .CH2OH, .CH(CH3)OH, (CH3)3CO., H.) using DMPO and its derivatives.
- Analysis of ESR spectra of the resulting spin adducts.
Main Results:
- The synthesized DMPO derivatives (4MDMPO, 4PDMPO, 4HMDMPO) exhibited higher melting points than DMPO.
- Hydrophilicity order was determined as 4HMDMPO > DMPO > 4MDMPO > 4PDMPO.
- Spin adducts of superoxide radicals (O2-.) with the derivatives showed ESR spectra similar to DMPO, with minimal line-width broadening despite diastereomer formation.
- Intensities and decay rates of O2-. adducts were comparable across all tested spin traps.
- Trapping of hydroxyl radicals (.OH) by 4MDMPO, 4PDMPO, and 4HMDMPO resulted in distinct eight-line ESR spectra, differing from the characteristic four-line spectrum of DMPO-.OH.
Conclusions:
- The novel DMPO derivatives possess altered physical properties (melting point, hydrophilicity) compared to DMPO.
- These derivatives are effective spin traps for superoxide radicals, showing similar trapping efficiency and adduct stability to DMPO.
- The distinct ESR spectral patterns observed for hydroxyl radical adducts suggest potential for differentiating radical species or reaction environments.