Glycine Specific Novel Maillard Reaction Products:  5-Hydroxy-1,3-dimethyl-2(1<i>H</i>)-quinoxalinone and Related Compounds

Abstract

A major product of the reaction of d -glucose with excess glycine was detected by Py/GC/MS analysis and subsequently synthesized and isolated using focused microwave irradiation at atmospheric pressure conditions. Spectroscopic analyses by NMR, FTIR, MS, and UV in conjunction with labeling studies have indicated the unknown compound to be 5-hydroxy-1,3-dimethyl-2(1 H )-quinoxalinone. Analysis of the mass spectra of the unknown compound obtained by reacting separately labeled [ 13 C]- d -glucoses with unlabeled glycines and reacting separately labeled [ 15 N]- and [ 13 C]glycines with unlabeled d -glucoses indicated the incorporation of 10 carbon atoms (six from sugar, one C-1 atom of glycine, and three C-2 atoms of glycine) and two nitrogens. In addition, other derivatives of quinoxalinone formed in d -glucose/glycine and d -glucose/ l -alanine mixtures were also tentatively identified based on similar amino acid incorporation patterns and mass spectroscopic analysis. Keywords: Amadori; decomposition mechanisms; Maillard reaction; 13 C-labeled d -glucose; [ 15 N]- and [ 13 C]glycine and l -alanine; pyrazinones; quinoxalinone; Py/GC/MS; microwave-assisted synthesis