Preparation, characterization and biological evaluation of copper(II) and zinc(II) complexes with Schiff bases derived from amoxicillin and cephalexin

Abstract

Copper(II) and zinc(II) complexes of Schiff bases obtained by condensation of amoxicillin and cephalexin with salicylaldehyde/pyridoxal were prepared and characterized by microanalytical, thermogravimetric, magnetic and spectroscopic data. All the complexes were found to be sixcoordinate and containing two water molecules. The electron paramagnetic resonance spectral lines exhibited rhombic distortion from axial symmetry, with g > g ⊥ > g e , in the copper(II) complexes. The geometry of the zinc(II) complexes appears to be octahedral. All the compounds under investigation showed antibacterial activity. The antibacterial activity showed the following trend: copper(II) complexes > zinc(II) complexes > Schiff base ligands > parent drugs. The copper(II) complexes with the Schiff bases derived from cephalexin showed substantially enhanced activity against Pseudomonas aeruginosa compared with the parent drug. All the copper complexes were also found to be active against kaolin paw oedema, whereas the parent drugs were inactive.

Synthesis, Spectral Characterization and Thermal Behaviour of New Metal(ii) Complexes With Schiff Base Derived From Amoxicillin

“…After 606 o C the mass loss has a higher value than that was recorded for Co(II) complex because in presence of carbon or CO the Ni oxide reduces to metal 27,28 as reactions II and III show, final residue being of 26.3%; this is consists of a mixture containing C, Ni and NiO. Similar events were reported for Cu(II) and Zn(II) complexes of Schiff bases obtained by condensation of amoxicillin and salicylaldehyde 10 . Other studies showed that amoxicillin was thermally decomposed at several stages with a total weight loss of 51.06%, leaving a residual mass at 350°C of 48.94%.…”

“…Atoms involved in coordination and the structure of these complexes depend on several factors including reaction medium, pH, temperature, solvents, etc. Iqbal M. et al 10 reported Cu(II) and Zn(II) complexes with Schiff base derived from amoxicillin and salicylaldehyde which were characterized by conventional methods such as microanalytical, magnetic and spectroscopic techniques associated with thermal analysis. Joshi S. et al 11 synthesized Co(II), Zn(II), Ni(II) and Mn(II) complexes with Schiff base derived from amoxicillin with two aldehydes -cinnamaldehyde and p-chlorobenzaldehyde -having improved antibacterial activity than the one that was found for free Schiff bases.…”

Effect of derivatization of sulfamethoxazole and trimethoprim with copper and zinc on their medicinal value

“…The copper complexes were found to be active whereas the zinc complexes and the parent drugs had no significant activity. The results are in line with previous findings (Iqbal et al, 1999(Iqbal et al, , 2005.…”

“…It has been demonstrated that transition elements play a very important role in of various medicinal compounds (Blower, 1999;Iqbal et al, 1999;Iqbal et al, 2005). In the present work we report new derivatives of sulfamethoxazole and trimethoprim with copper and zinc with greater medicinal value.…”

“…The hydrated complexes have significance in the enzymatic systems as the substrates can bind to zinc by substituting the coordinated water molecules in the complexes. Six-coordinate complexes of zinc (II) derived from indomethacin (Zhou et al, 2003) and other ligands (Iqbal et al, 2005;Niklas et al, 2003;Zhang and Janiak, 2001) have also been reported. The proposed structures of the complexes under investigation, on the basis of the above experimental evidence, are shown in Figs.…”