Collect. Czech. Chem. Commun. 2004, 69, 2081-2090

Reactivity of Free Radicals Generated from Neurotransmitters Studied by Electron Spin Resonance Spectroscopy

Alexander Tkáča,* and Eva Hanušovskáb

a Institute of Physical Chemistry, Faculty of Chemical and Food Technology, Slovak Technical University, 812 37 Bratislava, Slovak Republic
b Institute of Neuroimunology, Slovak Academy of Sciences, 845 10 Bratislava, Slovak Republic


Free phenoxy radicals derived from catecholamine-type neurotransmitters (dopamine, noradrenaline, adrenaline) σ-coordinated to Co(III) chelates were generated by the reaction of π-coordinated tert-butylperoxy radicals with the neurotransmitters in non-polar solvent at ambient temperature. The ESR signals of the formed complexes are split into the basic octet line resulting from the interaction of the unpaired electron of the phenoxy radical with the 59Co nucleus (I = 7/2). Increasing the polarity of the solution starts the decomplexation and the liberated phenoxy radicals of the neurotransmitters disappear by recombination or by H-abstraction from the added antioxidant. When vitamin E is added to the system, only the ESR signal of the stable α-tocopheroxy radicals is detectable. Similarly, in the presence of the antiarrhytmic drug Stobadine, only the signal of the corresponding nitrogen-centred radical is seen. In the presence of both antioxidants, rapid H-transfer occurs from vitamin E to the Stobadine radicals.

Keywords: Neurotransmitters; Free radicals; ESR spectroscopy; Dopamine; Antioxidants; Vitamin E; Stobadine.

References: 27 live references.