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, 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.