Novel dehydrofuroimidazole compounds formed by the advanced Maillard reaction of 3-deoxy-D-hexos-2-ulose and arginine residues in proteins

Similar unknown peaks were detected on an amino acid chromatogram of the acid hydrolysates in 3-deoxyglucosone (3DG)-lysozyme as well as glucose-lysozyme reaction systems. Unknown peaks were also detected in the acid hydrolysates of 3DG and N-alpha-benzoylarginine amide (BzArgNH(2)) reaction system. By this system, 2-(N-alpha-benzoyl-N-delta-ornithylamide)-5-(2,3,4- trihydroxybutyl)-4-imidazolone (S17) and 2-(N-alpha-benzoyl-N-delta-ornithylamide)-5-(2,3,4- trihydroxybutyl)-2-imidazoline-4-one (S12) were identified as major products in a previous paper (Hayase et al. Biosci. Biotechnol. Biochem. 1995, 59, 1407-1411). In addition, minor products were also formed from one molecule of BzArgNH(2) and two molecules of 3-DG. The minor product was identified as 2-(N-alpha-benzoyl-N-delta-ornithylamide)-5,6a-di(2,3,4- trihydroxybutyl)-5,6-dihydroxydehydrofuro[2,3-d]imidazole (S11). Periodic changes in the amounts of compounds S17, S12, and S11 suggest the formation of compound S17 via compound S12 by dehydration and oxidation from the BzArgNH(2)-3DG reaction system to be the major pathway, the formation of compound S11 by the addition of 3DG to compound S12 being the other pathway.