Complexes of N- and O-Donor Ligands as Potential Urease Inhibitors.

We report five new transition-metal complexes that inhibit the urease enzyme. Barbituric acid (BTA), thiobarbituric acid (TBA), isoniazid (INZ), and nicotinamide (NCA) ligands were employed in complexation reactions. The resulting complexes were characterized using a variety of analytical techniques including infra-red and UV-vis spectroscopy, 1H NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction analysis. We describe two mononuclear complexes with a general formula {[M(NCA)2(H2O)4](BTA)2(H2O)}, where M = Co (1) and Zn (2), a mononuclear complex {[Ni(NCA)2(H2O)4](TBA)2(H2O)} (3), and two polymeric chains of a general formula {[M(INZ) (H2O)3](BTA)2(H2O)3}, where M = Co (4) and Zn (5). These complexes displayed significant urease enzyme inhibition with IC50 values in the range of 3.9-19.9 µM.