In vitro and in vivo inhibition of muscle lipid and protein oxidation by carnosine

Carnosine, a beta -alanyl-L-histidine dipeptide with antioxidant properties is present at high concentrations in skeletal muscle tissue. In this study , we report on the antioxidant activity of carnosine on muscle lipid and pr otein stability from both in vitro and in vivo experiments. Carnosine inhib ited lipid peroxidation and oxidative modification of protein in muscle tis sue prepared from rat hind limb homogenates exposed to in vitro Fenton reac tant (Fe2+, H2O2)-generated free radicals. The minimum effective concentrat ions of carnosine for lipid and protein oxidation were 2.5 and 1 mM, respec tively. Histidine and beta -alanine, active components of carnosine, showed no individual effect towards inhibiting either lipid or protein oxidation. Skeletal muscle of rats fed a histidine supplemented diet for 13 days exhi bited a marked increase in carnosine content with a concomitant reduction i n muscle lipid peroxidation and protein carbonyl content in skeletal muscle caused by subjecting rats to a Fe-nitrilotriacetate administration treatme nt. This significant in vitro result confirms the in vivo antioxidant activ ity of carnosine for both lipid and protein constituents of muscle under ph ysiological conditions.