Influence of reaction conditions oil the oxidative behavior of model Maillard-reaction products

Model nondialyzable Maillard reaction products (MRPs) were synthesized by reacting D-glucose or D-fructose with L-lysine under four different initial reaction parameters (pH, water activity, reaction time, and temperature) and evaluated for potential antioxidant or prooxidant activity and genotoxic properties. All model Glu-Lys and Fru-Lys MRPs showed various degrees of antioxidant activity when evaluated in a metal-free model linoleic acid emulsion system using thiobarbituric acid (TBA) as an end point measure of lipid oxidation. The oxidative behavior of the same MRPs, when determined by an oxygen electrode in the presence of copper ions, consisted of both prooxidant and antioxidant activities for specific MRPs. Using an in vitro DNA model system, both Glu-Lys and Fru-Lys MRP mixtures induced significant (p less than or equal to 0.05) strand breakage in PM2 bacteriophage DNA at high concentrations (>0.001%, w/v). In general, Fru-Lys MRPs exhibited more prooxidant and genotoxic activity compared to Glu-Lys MRPs synthesized under identical conditions. The results demonstrate the importance of using a number of different in vitro model systems in defining the characteristic oxidative behavior of different MRPs synthesized under specifically different conditions.