Chemistry and some biological effects of model melanoidins and pigments as Maillard intermediates

Various pigments were formed in the D‐xylose‐glycine reaction system. Blue pigments (Blue‐M1 and Blue‐M2) and red pigments (Red‐M1 and Red‐M2) were generated in the Maillard reaction. Blue‐M2 is presented to have been generated by the reaction between Blue‐M1, which involved two pyrrolopyrrole structures as the major blue pigment, and di‐D‐xyluloseglycine. We identified red pigments as the isomers of addition compounds of D‐xyluloseglycine to condensated compound between pyrroropyrrole‐2‐carbaldehyde and pyrrole‐2‐carbaldehyde compounds. These pigments have polymerizing activities, suggesting that they are important Maillard reaction intermediates through the formation of melanoidins. Blue‐M1 as well as melanoidins effectively suppressed the peroxidation of linoleic acid. The scavenging activity toward Blue‐M1 on hydroxyl and DPPH radicals was also as strong as that of melanoidins. Furthermore, Blue‐M1 prevents the oxidative cell injury. Therefore, Blue‐M1 will be an antioxidant which protects against the oxidative stress in biological systems. Melanoidins induced IFN‐γ mRNA and IL‐12 mRNA expressions in spleen cells exposed to allergen and in macrophage‐like J774.1 cells, respectively. These findings suggest that melanoidins have suppressive effect on allergic reaction as a novel physiological effect.