There were significant differences between chemical
characteristics of ribose (Rib)-, glucose (Glc)-,
and fructose (Fru)-lysine (Lys) Maillard reaction
products (MRPs). Rib was the most reactive sugar and
exerted the greatest change in Maillard-reaction
(MR), followed by Glc and Fru in the sugar-Lys
model. All three sugar-Lys MRPs not only exhibited
strong free radical scavenging activity in chemical
systems, but also protected intestinal Caco-2 cells
from injury caused by oxidants and transition metal
ions. Different chemical characteristics of MRPs
generated by the three sugars could not be
associated with distinct antioxidant properties in
most cases. While antioxidant activities were
apparent for whole MRP mixtures, ethanol
precipitates (i.e., HMW fraction), more so than
ethanol extracts (i.e., LMW fraction), were mainly
responsible for scavenging HO and DPPH radicals
and protecting against both ferrous ion- and cupric
ion- induced cytotoxicity. Free radical scavenging
activities of MRPs were influenced not only by high
and low molecular fractions, but also by the source
of ROS present in the reaction environment.