Antioxidant and Prooxidant Activity of Xylose-Lysine Maillard Reaction Products

Abstract

Maillard reaction product, prepared by heating xylose and lysine at pH 9.0 and 100°C for 3 h, was fractionated by ethyl ether and ethanol into acidic, neutral and basic low molecular weight, ethanol-soluble and ethanol-insoluble fractions. The ethanol-soluble and -insoluble fractions were the major fractions of xylose-lysine Maillard reaction product (XL MRP), contributing 79.5 and 20.1%, respectively. XL MRP inhibited linoleic acid peroxidation, initiated by the Fenton reaction, but did not inhibit liposome peroxidation catalyzed by Fe2+, where it had a prooxidant action. XL MRP produced oxidative damage of deoxyribose and 2′-deoxyguanosine (2′-dG) initiated by the Fenton reaction. Ethanol-soluble and insoluble fractions also caused oxidative damage, while low molecular weight fractions had an antioxidant effect by inhibiting oxidative damage to deoxyribose initiated by the Fenton reaction. The prooxidant action of ethanol-soluble and insoluble fractions resembled uafractionated products in the 2′-dG assay. In these systems with deoxyribose, 2′-dG. Linoleic acid or liposomes, the XL MRP exhibited either antioxidant or prooxidant properties, which might be due to competition between reducing power and scavenging activity against the hydroxyl radical; the low molecular weight fractions did not have prooxidant activity in these systems.