Synthesis, characterization, in vivo antitumor properties of the cluster rhenium compound with GABA ligands and its synergism with cisplatin.

A new dirhenium(III) complex cis-[Re2(GABA)2Cl5(H2O)]Cl.2H2O with zwitterionic gamma-aminobutyrate ligands was prepared and characterized by spectral methods and crystallography. The structure of the compound is comprised of dinuclear complex cations (Re-Re 2.2437(3) A) involving cis-oriented double carboxylate bridges, four equatorial chloride ions and two weakly bonded aqua and chloride ligands in the axial positions at two rhenium centers (Re-O 2.363(3), Re-Cl 2.6735(12) A). Antitumor properties of the complex were studied in the model of tumor growth with the use of Wistar rats inoculated by tumor carcinoma Guerink cells. The introduction of the compound in dosage according to the scheme of antioxidant therapy, inhibited the tumor growth by ca. 60% and led to stabilization of red blood cells in the tumor-bearing organisms. The combined introduction of the compound and cisplatin had a significant impact on the tumor growth and the disappearance of the tumors in most of the animals.

Liposomal forms of rhenium cluster compounds: enhancement of biological activity.

Liposomal formulations of dinuclear cluster rhenium (Re) compounds were used in biochemical trials. Interaction of liposomal forms of some Re compounds with red blood cells in experiments in vitro showed strong cell-stabilizing properties. In the models of tumor growth and hemolytic anemia in vivo, liposomal forms had better therapeutic effects in comparison with their solutions. The process of formation of liposomes of cluster Re compounds with different organic ligands was investigated by the method of electronic absorption spectra and mechanism of their interactions with lipids is proposed. Encapsulation of cluster Re compounds to lipid coating may have activation significance for the quadruple Re-Re bond.