Preparation, characterization and biological evaluation of copper(II) and zinc(II) complexes with cephalexin

Copper(II) and zinc(II) complexes of cephalexin have been prepared and char acterized by microanalysis and by thermogravimetric, magnetic and spectrosc opic analysis. The complexes were found to be five-coordinate, monohydrate, and ML2 type. The electron paramagnetic resonance spectral lines revealed rhombic distortion from axial symmetry, with g(parallel to) > g(perpendicul ar to) > g(e), in the elongated-tetragonal copper(II) complex. The geometry of the zinc(II) complex seems to be square-pyramidal. On complexation with copper and zinc the antimicrobial activity of cephalexin improved signific antly. The copper complex was found to be active against kaolin paw oedema whereas the parent drug was inactive. These results suggest that the metallic elements should be seriously consid ered during drug design, and that complexes already reported should be subj ected to clinical evaluation. Their use could provide an easy way of improv ing the activity and reducing the toxicity of drug substances.