Spin Traps & Spin Probes

Spin trapping is a common analytical method for the detection of free radicals. The spin trap molecule (e.g., PBN, DMPO, TEMPO) reacts with a typically transient free radical species, thus “trapping” the free radical in the form of a more stable spin adduct. Adducts can then be detected using electron paramagnetic resonance (EPR) spectroscopy.

Enzo offers a variety of spin traps and probes for the detection of general or specific free radical species. Our compounds are of the highest purity, ensuring the most consistent results.

• Highest purity spin traps for in vitro and in vivo applications
• No additional purification is required
• All products are quality tested by ESR spectroscopy

Spin trapping is widely used for unambiguous detection of free radicals, such as superoxide radical. Unfortunately, EPR detection of the O₂ ^•- radicals in biological systems is limited by slow kinetics of O₂ ^•- spin trapping (~55 M-1s-1) and biodegradation of the radical adducts (reduction to EPR silent hydroxylamines and oxidation to secondary nitrones) [1]. It has been previously shown that PP-H is an effective scavenger of the O₂ ^•- [2], rapidly reacts with O₂ ^•- to form stable nitroxides with a much longer half-life than O₂ ^•- radical adducts. This is a distinct advantage of cyclic hydroxylamines over nitrone spin traps, which form relatively stable O₂ ^•- adducts in cell-free systems [3], but these adducts rapidly degrade in biological samples [4]. Cyclic hydroxylamines react with O₂ ^•- 100 times faster (~104 M-1s-1) than spin traps, which allow cyclic hydroxylamines to compete with cellular antioxidants and react with intracellular O₂ ^•- . The lack of specificity of cyclic hydroxylamines can be overcome by use of superoxide dismutases or inhibitors of O₂ ^•- production by NADPH oxidase, uncoupled eNOS (NOS III), xanthine oxidase, apocynin, L-NAME, and oxypurinol [5-7]. Cationic, anionic and neutral spin probes with various lipophilicity and cell permeability allow site-specific O₂ ^•- detection with higher sensitivity than nitrone spin traps.

1. M. Sentjurc & R. P. Mason; Free Radic. Biol. Med. 13, 151 (1992)
2. S. I. Dikalov, et al.; Arch. Biochem. Biophys. 402, 218 (2002)
3. H. Zhao, et al.; PNAS 102, 5727 (2005)
4. K. Zwicker, et al.; Arzneimittelforschung 48, 629 (1998)
5. N. Kuzkaya, et al.; Biochem. Pharmacol. 70, 343 (2005)
6. K. E. Wyche, et al.; Hypertension 43, 1246 (2004)
7. J. S. McNally, et al.; Arterioscler. Thromb. Vasc. Biol. 25, 1623 (2005)