Synthesis, Structure, and Radioprotective Activity of the Palladium (II) Complex With Mexidol

Abstract

New complex compounds of palladium (II) with biologically active ligand 2 - ethyl - 6 methyl - 3 - hydroxy-pyridine - mexidol in acidic medium (pH = 5,3) of the following composition have been synthesized – (C8H12O⊕N)2 [PdCl4]. In this case, the ligand is protonated and as a single-charged cation occupies an external coordination sphere. The structure of the complex is proved by X-ray structure analysis. It is shown that the structure is constructed of an isolated complex anion [PdCl4]2- and cation C8H12O⊕N. The square planar coordination of the palladium atom is formed from three chlorine atoms and the formed tetraacidoanion ligand forms a hydrogen bond. The average length of Pd-Cl bond is 2, 3030 Α°, there are no deviations from 900 valence angles of Cl-Pd-Cl. The palladium atom is not shifted from the plane coordination polyhedron (square) and therefore trance angles of Cl-Pd-Cl are 1800. Two different lengths -2,289 Α° and 2,713 Α° of hydrogen bonds are related to the geometric location of the ligand functional group. The obtained 2 – ethyl – 6 – methyl – 3 -hydroxypyridinetrachloro - palladium - mexidazole was tested for radioprotective properties. Toxicity of the preparation is LD50 - 240 mg/kg of animal weight. Toxicological studies of mexidazole in mice, rats and dogs did not reveal cardiotoxic, immunotoxic, embryonic, nephrotoxic, hematoxic and other types of side effects. Mexidazole is removed from the body with urine 5-8 hours after intravenous injection. The carried out biological test showed that the compound, along with radioprotective properties, has some antitumor activity.