EMPO is a hydrophilic cyclic nitrone analog of the free radical spin trap DMPO . The EMPO-superoxide adduct (EMPO-OOH) exhibits an ESR spectrum that is similar to the DMPO-OOH spectrum. [1] However, the EMPO-OOH adduct is about 5-8 times more stable (t1/2 = 4.8 - 8.6 min) and does not spontaneously decay to the hydroxyl adduct, making spectral interpretation less difficult. [1][2][3]
Reference:
[1]. Olive, G., Mercier, A., Le Moigne, F., et al. 2-ethoxycarbonyl-2-methyl-3,4-dihydro-2H-pyrrole-1-oxide: evaluation of the spin trapping properties. Free Radic. Biol. Med. 28(3), 403-408 (2000).
[2]. Stolze, K., Udilova, N., and Nohl, H. Spin adducts of superoxide, alkoxyl, and lipid-derived radicals with EMPO and its derivatives. Biol. Chem. 383(5), 813-820 (2002).
[3]. Zhang, H., Joseph, J., Vasquez-Vivar, J., et al. Detection of superoxide anion using an isotopically labeled nitrone spin trap: Potential biological applications. FEBS Lett. 473(1), 58-62 (2000).