The Origin and Fate of α-Dicarbonyls Formed in Maillard Model Systems: Mechanistic Studies Using 13 C- and 15 N-Labelled Amino Acids

Summary The origin of reactive α-dicarbonyl species formed during the Maillard reaction can be identified through labelling studies using 13C-labelled sugars and amino acids. Such studies could be performed conveniently by Py-GC-MS. Analysis of model systems consisting of short-chain dicarbonyls. D-glucose and labelled glycine; indicated that α-ketoaldehydes produced by retro-aldol reactions of sugar derivatives could undergo chain elongation through incorporation of amino acid carbons, by two processes; (1) aldol condensation with Strecker aldehydes or (2) aldol condensation with the α-carbon of the amino acids followed by deamination. The resulting α-carboxydicarbonyl, in turn, can either undergo decarboxylation to produce dicarbonyls that incorporate the side chain of the amino acids or undergo further additions of amino acids to produce pyrazinones.