Unexpected oxidation of nitrendipine. Properties of oxidized nitrendipine and its Cu(II) complex

Abstract

In the search of improving the biological properties of medicines by metal complexation the calcium channel blocker nitrendipine (ntp) was selected to design its copper(II) complex. During the preparative the 1- 4-dihydropyridine moiety of the ligand was oxidized to pyridine (oxntp) and its copper(II) complex [Cu(oxntd)2Cl2] (Cuoxntp), has been obtained. The crystal structure of the complex has been determined by X-ray diffraction methods. The complex is centre-symmetric with the metal in an almost perfect rhombic environment, coordinated to two inversion-related organic ligands through their pyridine N-atoms and to two chlorine ions.The complex, ntp and oxntp have been characterized by vibrational and electronic spectroscopies. The antioxidant behavior of ntp, common for dihydropyridines, was determined by the DPPH assay. The oxidized ligand does not show antioxidant behavior while its copper(II) complex acted as a moderate antioxidant agent.