THE PREPARATION AND CHARACTERIZATION OF SOME AMADORI COMPOUNDS (1-AMINO-1-DEOXY-D-FRUCTOSE DERIVATIVES) DERIVED FROM A SERIES OF ALIPHATIC OMEGA-AMINO ACIDS

Amadori compounds (1-amino-1-deoxy-D-fructose derivatives) were prepared by reacting D-glucose with a series of aliphatic amino acids. These include Amadori compounds derived from glycine (1), beta-alanine (2), gamma-amino butyric acid (3), delta-aminovaleric acid (4), epsilon-aminocaproic acid (5) and N-alpha-formyl-L-lysine (6). In the FAB mass spectra, molecular-ion dusters as well as fragment ions corresponding to loss of water or CO2 molecules were observed. The C-13 NMR spectra indicate that all the compounds are conformationally unstable, but that the predominant form present in solution (D2O) is the beta-pyranose form. The H-1 NMR spectra of 1 and 2 indicate a slow rotation around the C-1-C-2 bond, possibly as a result of an intramolecular hydrogen bond involving the carboxyl group. The pK(a)'s of all compounds were measured by pH-potentiometric titration in 0.2 M KNO3 solution at 25 degrees C. All compounds showed a decrease in the basicity of their amino groups (in the order of similar to 1.5 of the K-a value), and 1 and 2 showed a decrease in the basicity of their carboxyl groups (in the order of similar to 0.2) in comparison with that of parent amino acids.