Metal chelating and antioxidant activity of model Maillard reaction products

Model glucose-lysine (Glu-Lys) and fructose-lysine (Fru-Lys) Maillard Reaction products (MRPs) were generated using 14 different reaction combinations, by varying four experimental parameters: time, temperature, initial water activity (aw), and initial pH. The synthesized MRPs were analyzed for their potential copper chelating, antioxidant or prooxidant, and genotoxic activities. Yield of MRPs varied depending on the conditions used to generate them. Amount of copper bound to MRPs ranged from 0.031-1.574 and 0.016-2.267 :mol copper per mg MRP for different Glu-Lys and Fru-Lys MRPs, respectively, in different synthesis experiments. The assessment of antioxidant activity by the 2-thiobarbituric acid (TBA) method using a lipid system devoid of copper ions showed varying antioxidant activity for both Glu-Lys and Fru-Lys MRPs. Using an oxygen electrode for the measurement of oxygen depletion in a model lipid system containing copper, as an endpoint measure of lipid peroxidation, 7 antioxidant, 2 prooxidant, and 4 inactive MRPs and 5 antioxidant, 5 prooxidant, and 2 inactive MRPs were obtained for Glu-Lys and Fru-Lys MRP synthesis experiments, respectively. All derived MRPs showed DNA strand breaking activity above a concentration of 0.001% (w/v). The results indicate the importance of reaction conditions and the source of reducing sugar in the generation of MRPs with variable antioxidant, prooxidant, and genotoxic activities.