Chiral ligand induced geometrical type of isomerism in Schiff-base Copper (II) complexes with urease inhibitory activities

Enzyme urease plays a significant role in the pathogenesis of several diseases and has practical implications in fields such as agriculture and chemical analysis. Four new copper(II) complexes with Schiff-base ligands obtained from the template synthesis of 2-formylphenoxyacetic acid (fphaa) with DL-alpha-alanine, beta-alanine, taurine, and gamma-aminobutanoic acid were synthesized in addition to the previously described [Cu(fphaa-gly)(H2O)] derived from glycine. Crystallographic study of two solvates of Cu(fphaa-alpha-ala)center dot S (where S = H2O or DMSO) showed similarity of these complexes with the one derived from glycine. In addition, an E/Z isomerism originating in a different molecular arrangement of the aqua ligand with respect to the methyl group from alanine was described in the aqua complex. Only Z isomers were found in the complex with DMSO. All prepared complexes showed excellent inhibitory properties against jack bean urease (IC50 = 0.53-0.71 mu mol/dm(3)), considerably better than the standard inhibitor acetohydroxamic acid (IC50 = 185 mu mol/dm(3)).