Syntheses, Characterization and Biological Activity of Novel Thiazoylazo Dye and Its Coordination Compounds

The present work describes the synthesis of a novel heterocyclic azo dye by general diazonization of 2-amino-4,5-dimethylthiazole followed by the diazo- coupling of the resulting diazonium ion with 5-methyl-2-(propan-2-yl)phenol to obtain ligand L. This was characterized using Fourier-transformed infrared and electronic spectrophotometry. Ligand L was further coordinated with five metal ions, M:L, 1:2 [M = Cu(II), Mn(II), Zn(II), Ni(II) and Co(II)]. The coordination compounds obtained were characterized by electronic, IR spectrophotometry, magnetic susceptibility and percentage metal analyses. The results obtained suggested that a thiazoylazo dye was obtained as ligand L. It was proposed that two molecules of the solvent coordinated to the metal ion in addition with the ligands to give an octahedral geometry for copper(II), manganese(II) and nickel(II) complexes. On the other hand, square planar geometry was suggested for zinc(II) and cobalt(II) complexes. The anti-infla- mmatory activity of the ligand and coordination compounds was evaluated using four in vitro-based assays viz: xanthine oxidase and lipoxygenase inhibition assay, membrane stability and protein denaturation assay. The synthesized compounds generally exhibited good anti-inflammatory activity in all the assays carried out. However, the reference standards, in this instance, were more effective in the case of xanthine oxidase, lipoxygenase and protein denaturation inhibitory assays. For the membrane stability study, the coordination compounds and ligand L elicited more potent anti-inflammatory activity than the standard drug.