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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.

Two novel derivatives of carnosine--(S)-trolox-L-carnosine (STC) and (R)-trolox-L-carnosine (RTC) are characterized in terms of their antioxidant and membrane-stabilizing activities as well as their resistance to serum carnosinase. STC and RTC were synthesized by N-acylation of L-carnosine with (S)- and (R)-trolox, respectively. STC and RTC were found to react more efficiently with 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and protect serum lipoproteins from Fe(2+)-induced oxidation more successfully than carnosine and trolox. At the same time, STC, RTC and trolox suppressed oxidative hemolysis of red blood cells (RBC) less efficiently than carnosine taken in the same concentration. When oxidative stress was induced in suspension of cerebellum granule cells by their incubation with N-methyl-D-aspartate (NMDA), or hydrogen peroxide (H(2)O(2)), both STC and RTC more efficiently decreased accumulation of reactive oxygen species (ROS) than carnosine and trolox. Both STC and RTC were resistant toward hydrolytic degradation by human serum carnosinase. STC and RTC were concluded to demonstrate higher antioxidant capacity and better ability to prevent cerebellar neurons from ROS accumulation than their precursors, carnosine and trolox.

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