Superoxide anion radical scavenging property of catecholamines

The direct effect of the four catecholamines (adrenaline, noradrenaline, dopamine and isoproterenol) on superoxide anion radicals (O-2(center dot)) was investigated. The reaction between 18-crown-6-ether and potassium superoxide in dimethylsulfoxide was used as a source of O-2((center dot) over bar). The reactivity of catecholamines with O-2((center dot) over bar) was examined using chemiluminescence, reduction of nitroblue tetrazolium and electron paramagnetic resonance spin-trapping techniques. 5,5-Dimethyl-1-pyrroline-N-oxide was included as the spin trap. The results showed that the four catecholamines were effective and efficient in inhibiting chemiluminescence accompanying the potassium superoxide/18-crown-6-ether system in a dose-dependent manner over the range 0.05-2 mm in the following order: adrenaline>noradrenaline>dopamine>isoproterenol, with, IC50=0.15 +/- 0.02 mm 0.21 +/- 0.03 mm, 0.27 +/- 0.03 mm and 0.50 +/- 0.04 mm, respectively. The catecholamines examined also exhibited a strong scavenging effect towards O-2((center dot) over bar) when evaluated this property by the inhibition of nitroblue tetrazolium reduction (56-73% at 1 m concentration). A very similar capacity of O-2((center dot) over bar) scavenging was monitored in the 5,5-dimethyl-1-pyrroline-N-oxide spin-trapping assay. The results suggest that catecholamines tested may involve a direct effect on scavenging O-2(-) radicals. Copyright (c) 2013 John Wiley & Sons, Ltd.