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

[Image: see text] 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, (1)H NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction analysis. We describe two mononuclear complexes with a general formula {[M(NCA)(2)(H(2)O)(4)](BTA)(2)(H(2)O)}, where M = Co (1) and Zn (2), a mononuclear complex {[Ni(NCA)(2)(H(2)O)(4)](TBA)(2)(H(2)O)} (3), and two polymeric chains of a general formula {[M(INZ) (H(2)O)(3)](BTA)(2)(H(2)O)(3)}, where M = Co (4) and Zn (5). These complexes displayed significant urease enzyme inhibition with IC(50) values in the range of 3.9–19.9 μM.