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Detection of Nitric Oxide and Superoxide Radical Anion by Electron Paramagnetic Resonance Spectroscopy from Cells using Spin Traps
Published on: August 18, 2012
Improved spin trapping properties by beta-cyclodextrin-cyclic nitrone conjugate.
Yongbin Han1, Beatrice Tuccio, Robert Lauricella
1Department of Pharmacology, The Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University, Columbus, Ohio 43210, USA.
The Journal of Organic Chemistry
|August 19, 2008
Summary
A novel beta-cyclodextrin-cyclic nitrone conjugate (CDNMPO) was synthesized for enhanced spin trapping of superoxide radicals. This compound shows improved reactivity and adduct stability, aiding in radical detection.
Area of Science:
- Biochemistry and Biophysics
- Chemical Biology
- Spectroscopy
Background:
- Spin trapping with nitrones and electron paramagnetic resonance (EPR) spectroscopy is crucial for identifying transient radicals.
- Growing interest in nitrone pharmacology necessitates improved spin traps with controlled cellular delivery.
- Existing spin traps require optimization for enhanced reactivity and stability, particularly for biologically relevant radicals.
Purpose of the Study:
- To synthesize and characterize a novel beta-cyclodextrin (beta-CD)-cyclic nitrone conjugate (CDNMPO) for improved spin trapping.
- To evaluate the spin trapping efficiency and kinetics of CDNMPO for superoxide radical anion (O2(*-)).
- To utilize computational methods to rationalize the design and stability of the new spin trap.
Main Methods:
- Synthesis and characterization of the beta-cyclodextrin-cyclic nitrone conjugate (CDNMPO) using 1D and 2D NMR.
- Spin trapping experiments using CDNMPO to detect superoxide radical anion (O2(*-)) via EPR spectroscopy.
- Kinetic analysis of O2(*-) adduct formation/decay using singular value decomposition and pseudoinverse deconvolution.
- Molecular modeling to understand nitrone-beta-CD interactions and adduct stability.
Main Results:
- CDNMPO was successfully synthesized, existing in two stereoisomeric forms (5S- and 5R-).
- CDNMPO exhibited distinct EPR spectra for O2(*-) compared to other radicals.
- Kinetic analysis yielded a bimolecular rate constant (k = 58 +/- 1 M(-1) s(-1)) and a maximum half-life (t(1/2) = 27.5 min) for O2(*-) adducts at pH 7.0.
- Molecular modeling supported enhanced O2(*-) adduct stability due to intramolecular interactions with beta-CD.
Conclusions:
- The synthesized CDNMPO demonstrates effective spin trapping of superoxide radicals with enhanced reactivity.
- Beta-cyclodextrin conjugation improves the stability of O2(*-) adducts through intramolecular interactions.
- Computational approaches are valuable for designing advanced spin traps with tailored properties for radical detection.
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