Prediction of stability of copper(II) and nickel(II) complexes with fructose-amino acids from the molecular graph models developed on amino acid chelates

Topological analysis was applied for the estimation of stability constants of copper(II) and nickel(II) mono- (K-1) and bis-complexes (beta(2)) with fructose-amino acid adducts (N = 5). Calibration models were built by correlating the of stability constants of Cu-II and Ni-II mono- and bis-complexes with alpha-amino acids on their (3)chi(v) connectivity index. The bivariate regression with the indicator variable (In = 1 for Cu, In = 0 for Ni) was also applied. By averaging the theoretically obtained values, log K-1 values of fructose-amino acids were estimated with the rms error of 0.22 and 0.27 log K units for Cu and Ni chelates, respectively. The best estimates of log beta(2) values yielded the rms error of 0.76 and 0.75 log beta units for Cu and Ni chelates, respectively. However, the results for nickel(II) bis-chelates were improved by the introduction of explicit interaction of amino acid side chains with fructose moiety, yielding rms = 0.34 log beta units.