Synthesis and Characterization of Vanadium Complexes as Insulin Mimics for Diabetes Types 2 and Their Impact on Rats

Abstract

In this research oxovanadium complexes and di oxovanadium complexes (C1-C15) and ligands (L1-L16), specifically, organic ligands considered to be of biological importance, as insulin mimics. They were synthesized, and divided in four groups: vanadium salts with amino acids, carboxylic acids, thiosemicarbazone, 1.10 phenanthoroline, 3-Hydroxypyridine and Schiff-base ligands. The complexes were characterized by conductivity measurements; magnetic susceptibility, UV-Vis, IR, thermal gravimetric analysis TGA, III

1 H and 13 C NMR.The molecular structure of the complexes (C1- C15) were confirmed using the DFT calculation to obtain the optimized geometries using the Gaussian 09 program at the B3LYP/LANL2DZ level of theory. The vanadium atoms in the complexes were coordinated in different distorted geometries with ligands (L1- L16), acting as a bi-dentate and tridentate ligands through the amino nitrogen atoms, sulfur atom, phenol oxygen atom and carboxylate oxygen atom. The total energies for the highest occupied molecular orbital (HOMO) energies, the lowest unoccupied molecular orbital (LUMO) energies and the dipole moment for the ligands (L1-L16), and their complexes (C1-C15), were calculated, It was found that the more negative value of total energy of the complexes than that of free ligands indicates their extra stability polarity, much larger enhance than those of free ligands. As vanadium compounds insulin sensitivity and act as insulin mimetic and has anti-diabetic effects, complexes of C1, C6, C10, C13 were further tested on rats after they had been injected by streptozotocin, that causes a type 2 diabetes. In this study intra-peritoneal administration active anti-diabetic organic vanadium complexes. After four weeks of complexes treatment, the result showed significant hyperglycemia improvement indicating that vanadium complexes had anti-diabetic and insulin-sensitizing effects on the diabetic rats.