Transition metal complexes (M = Cu, Ni and Mn) of Schiff-base ligands: Syntheses, crystal structures, and inhibitory bioactivities against urease and xanthine oxidase

Six new transition metal complexes (M=Cu(II), Ni(II) and Mn(III)) of tridentate (H2L1, HL2) and/or bidentate (HL3, HL4) Schiff-base ligands, obtained from the condensation of salicylaldehyde with glycine, N-(2-aminoethyl)morpholine, 4-(2-aminoethyl)phenylic acid and 4-(2-aminoethyl)benzsulfamide, respectively, were synthesized and structurally determined by single-crystal X-ray analysis. Complexes 1-6 were evaluated for their effect on the jack bean urease and xanthine oxidase (XO). Copper(II) complexes 1-3 (IC50=0.43-2.25 mu M) showed potent inhibitory activity against jack bean urease, comparable with acetohydroxamicacid (IC50=42.12 mu M), which is a positive reference. And these copper(II) complexes (IC50=10.26-15.82 mu M) also exhibited strong ability to inhibit activity of XO, comparable to allopurinol (IC50=10.37 mu M), which was used as a positive reference. Nickel(II) and manganese(III) complexes 4-6 showed weak inhibitory activity to jack bean urease (IC50=4.36-8.25 mu M) and no ability to inhibit XO (IC50>100 mu M). (C) 2007 Elsevier B.V. All rights reserved.