Evidence for a direct interaction of superoxide anion radical with carnosine

Abstract

Using photochemiluminescence, the interaction between carnosine and superoxide anion was measured directly. Carnosine at physiological concentrations decreased the amplitude of luminol chemiluminescence like superoxide dismutase (SOD) did, and prolonged the lag-period of the chemiluminescence similar to the effect of ascorbic acid. From the interaction of nitro blue tetrazolium with superoxide anion generated by the xanthine oxidase system, the constant for interaction of carnosine with O2(@?) was calculated to be 105 M-1.sec-1. The possible biological significance of the quenching of superoxide anion by carnosine is discussed.