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

•Synthesis of new amino based Schiff base ligand containing gabapentin moiety.•Single crystal structural analysis of the ligand.•Metal coordination of the ligand with Co, Ni, Cu and Zn(II) metals.•Spectroscopic characterization of the ligand and complexes.•Xanthine oxidase inhibition activities of all the synthesized compounds for the possible treatment of Gout disease.

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 μM ± 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.

Graphical abstractTransition metal complexes of new gabapentin based Schiff base ligand were synthesized and characterized. All the compounds were screened for their xanthine oxidase inhibition activities. Zinc containing compound was found active.Figure optionsDownload full-size imageDownload as PowerPoint slide