The detection of some dicarbonyl intermediates arising from the degradation of Amadori compounds (the Maillard reaction)

Three Amadori compounds, N-(1-deoxy-d-fructos-1-yl)-glycine (1), Nϵ-(1-deoxy-d-fructos-1-yl)-Nα-formyl-l-lysine (2) and N,N-di-(1-deoxy-d-fructos-1-yl)-glycine (3) were incubated (37°C) in buffered solutions having pH values corresponding to the pKa of the substituted amino group in the presence of aminoguanidine. The dicarbonyl intermediates that were produced were trapped as the stable triazine derivatives (6a, 6b and 7), and their yields were measured as a function of reaction time. The triazines derived from both 1-deoxy-2,3-d-erythro-hexodiulose (“1-deoxyglucosone”, 5) and 3-deoxy-d-erythro-hexos-2-ulose (“3-deoxyglucosone”, 4) were detected as the trimethylsilyl derivatives by GLC and were unequivocally identified by comparison with authentic standards and by GLC-MS. Varying the pH of the incubation mixture had little effect on the ratio or the nature of the dicarbonyl compounds produced. This represents an unusual situation, wherein two different dicarbonyl intermediates (one produced, presumably, as a result of initial 1,2-enolization and the other, presumably as a result of 2,3-enolization) were identified in the same Maillard reaction mixture.