STRUCTURE FEATURES AND PHARMACOLOGICAL PROPERTIES OF GERMANIUM(IV) COMPLEXES WITH 1-HYDROXYETHANE-1,1-DIPHOSPHONIC ACID

The review article presents the results of systematic research by the authors of a number of heterometals and mixed-ligand 1-hydroxyethane-1,1-diphosphonatogermanates, their structure, biological and pharmacological properties. It was observed, that hexanuclear cyclic complex anions of the general composition [Ge6(µ-OH)6-n(µ-O)n(µ-hedp)6](6+n)− were present in the aqueous solutions of investigated compounds. At the same time, the composition and charge of the anion in each compound obtained in the solid state depends on the nature of the cation. They all have a common hexameric structure, with germanium atoms connected in pairs by 1-hydroxyethane-1,1-diphosphonate, hydroxo-, or oxo- and hydroxo-bridges. The coordination polyhedron Ge is a curved octahedron with two six-membered GeO2P2C cycles and an eight-membered bimetallic Ge2O4P2 closing, and each ligand performs a tetradentate tris(chelate)-µ-bridging function. The ratio of formed oxo- and hydroxo-bridges and, as a result, the charge of the anion varies under the influence of cation parameters and electrosta­tic interactions. Acute and chronic toxicity studies proved the safety of 1-hydroxyethane-1,1-diphosphonatogermanates. Complexes show a wide spectrum of pharmacological activity: antihypertensive, antiarrhythmic, hepatoprotective, cerebroprotective etc.The pharmacological and biological activities of 1-hydroxyethane-1,1-diphosphonatogermanates(IV) are ensured by the combined action of all biologically active components, which do not compete but show synergistic action. It was concluded that the preparation of new complexes of germanium(IV) with etidronic acid by chemical modification of their composition is a promising area of research in the field of creating coordination compounds with a wide range of pharmacological effects.