Synthesis, characterization, antioxidant and selective xanthine oxidase inhibitory studies of transition metal complexes of novel amino acid bearing Schiff base ligand

The amino acid [1-(aminomethyl)cyclohexyl]acetic acid was reacted with 2-hydroxynaphthaldehyde to produce the Schiff base ligand [1-({[(Z)-(2-hydroxynaphthalen-1-yl)methylidene]amino}methyl)cyclohexyl]acetic acid (H-HMAC) which was fully characterized spectroscopically and by single crystal diffraction. It was reacted with metal ions to produce compounds with composition [M(HMAC)(2)] [M = Co(II), Ni(II), Cu(II) and Zn(II)], which were characterized spectroscopically, with distorted tetragonal geometries assigned based on spectroscopic and B3LYP theoretical studies. All synthesized compounds were studied for their thermal stabilities under static air. The coordination compounds were also screened for their free radical scavenging properties using DPPH free radicals and xanthine oxidase inhibitory activities. Only the zinc complex was found to be an inhibitor of the enzymatic activity with IC50 = 0.7 +/- 0.01 mu M +/- SEM better than the standard reference drug used. The inhibitory activity was structurally rationalized by carrying out molecular modeling studies using the auto dock program. (C) 2015 Elsevier B.V. All rights reserved.