Superoxide anion scavenging capacity measured by a polarographic method. Comparison with a colourimetric method.
A polarographic method to assess the scavenging capacity of a molecule for O2-. is proposed. This method is based on the fact that O2-. is not detected by the Clark electrode and that a scavenger competes with spontaneous dismutation of O2-. So, the reduction of O2 into O2-. and the decomposition of H2O2 by catalase, releasing O2, show a biphasic kinetic. Various kinetic parameters can be used to calculate the nmol of O2-. scavenged and also supply data on the reaction mechanisms (oxidation or reduction of O2-.) involved in scavenging. This method presents several other advantages: scavenging capacity can be assayed without added indicators which themselves behave as scavengers (as demonstrated for NBT), the presence of scavengers which interfere with the O2-. generating system (xanthine-xanthine oxidase) does not invalidate the measurements made.
Darmon
N
N
Institut de Physiologie, Toulouse, France.
Fernandez
Y
Y
Periquet
A
A
Mitjavila
S
S
D000838:Anions / Q000494:pharmacology; D003124:Colorimetry; D003574:Cytochrome c Group / Q000737:chemistry; D016166:Free Radical Scavengers; D006861:Hydrogen Peroxide / Q000737:chemistry; D007700:Kinetics; D009580:Nitroblue Tetrazolium; D010084:Oxidation-Reduction; D011048:Polarography; D015203:Reproducibility of Results; D013481:Superoxides / Q000494:pharmacology*; D019820:Xanthine; D014969:Xanthine Oxidase; D014970:Xanthines
D000838:Anions; D003574:Cytochrome c Group; D016166:Free Radical Scavengers; D014970:Xanthines; D013481:Superoxides; D019820:Xanthine; D009580:Nitroblue Tetrazolium; D006861:Hydrogen Peroxide; D014969:Xanthine Oxidase