Sugar chirality modulates the antioxidant and bacterial growth-inhibitory properties of Maillard reaction products from glucose and lysine

The Maillard reaction generates compounds with antioxidant and bacterial growth-inhibitory properties, but the influence of sugar stereochemistry on Maillard reaction products (MRPs) remains insufficiently explored. This study investigated the impact of glucose chirality on the antioxidant and growth-inhibitory activities of MRPs formed with L-lysine. MRPs were prepared by heating D-glucose or L-glucose with L-lysine under identical aqueous conditions. Antioxidant activities were assessed using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), Ferric Reducing Antioxidant Power (FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays, while growth inhibition against Listeria monocytogenes was evaluated by broth microdilution growth kinetics, apparent Minimum Inhibitory Concentration (apparent MIC) estimation, and colony recovery. D-glucose-derived MRPs (MRP-D-Glu) and L-glucose-derived MRPs (MRP-L-Glu) exhibited similar ABTS and DPPH radical-scavenging capacities, whereas MRP-L-Glu demonstrated significantly higher ferric reducing power. Additionally, both MRPs inhibited L. monocytogenes growth at 50% (v/v), but only MRP-L-Glu maintained growth inhibition at 25% (v/v). Viable colonies were recovered at the highest MRP level, indicating that the minimum bactericidal concentration was not reached. Sugar stereochemistry therefore selectively modulates ferric reducing power and bacterial growth inhibition, although the molecular basis remains unresolved.