Abstract

SYNTHESIS AND CHARACTERIZATION OF NOVEL PYRIDINIMINE-BASED SCHIFF BASE LIGANDS AND THEIR Cu (II) COMPLEXES FOR BIOMEDICAL APPLICATIONS

Gajanan Hegde, Shivarudrappa Honnali Pattanashetty, Yallappa Shiralgi*, Talavara Venkatesh, Nagendra Sastry Yarla, Bharath Raj B., Mohammed Shafeeulla R., Dhananjaya B. L.

Abstract

In this study, Cu (II) complexes with pyridinimine-based Schiff base tetradentate ligands were synthesized, by condensation of pyridine with substituted 3-formyl-2-hydroxy quinolines. These copper complexes were characterized using analytical techniques such as elemental analyses (CHN), spectral analyses (FTIR, 1HNMR and ESR) and physicochemical studies (molar conductance and magnetic moment). FTIR spectra demonstrated coordination mode for the Schiff base ligand that behaves as tetradentate with Cu2+ ions. The elemental analysis by magnetic studies and ESR spectra suggested the distorted square-planar geometry for these complexes. Further, ESR spectra of the crystalline Cu (II) complexes showed covalent nature for the metal ligand bond. The molar conductance in dimethylformamide solution indicated that all complexes are nonelectrolytes. Furthermore, these compounds were tested for their therapeutic potentials, using rat and mouse models. The Cu (II) complexes with pyridinimine-based Schiff base tetradentate ligands exhibited potent anti-inflammatory, anti-arthritic and analgesic activities in vivo. In addition, the serum copper levels were significantly higher in rats, which received copper complexes. However, these copper complexes did not exhibit acute toxicity or deaths at the higher dose (800 mg/kg) tested in the present investigation. In conclusion, copper complexes-mediated anti-inflammatory activity might be through the stimulation of copper-dependent enzymes such as ceruloplasmin and super-oxide dismutase, both of which have free radical scavenging properties.

Keywords: Schiff base, Cu (II) complex; pyridinimine, Spectral analysis, Biological evaluations.