Potential antidiabetic molecule involving a new chromium(III) complex of dipicolinic and metformin as a counter ion: Synthesis, structure, spectroscopy, and bioactivity in mice

Abstract The chromium(III) complex, Cr(C7H3NO4)2·C4H12N5 (1), was synthesised by chelating chromium with dipicolinic (H2dipic) in methanol, and its structure was characterised using elemental analysis (EA), spectroscopy (infrared, UV–visible, and fluorescence) and single-crystal X-ray method. The density functional theoretical (DFT) computation was performed using the Gaussian 09 package. The stability of solution at different temperatures and pH values, the electrochemical, morphological and thermal properties of complex 1 were discussed. The preliminary bioactivities of complex 1 in streptozotocin (STZ)-induced type 2 diabetes mellitus (T2DM) mice were investigated using daily oral gavage for 12 weeks. The cytotoxicity was assessed using the methyl thiazolyl tetrazolium (MTT) assays, and the acute toxicity experiment test was carried out on healthy C57BL/6 mice with this complex. The complex 1 crystallised in the monoclinic system with the space group P2(1)/n, R1 = 0.0642. The DFT-optimised structure of complex 1 was in excellent agreement with the X-ray crystal structure. The complex 1 exhibited good physical and chemical properties and beneficial function on blood glucose and lipid metabolism for T2DM. The antidiabetic activity of chromium(III) might be associated with chromium(VI). Furthermore, the cytotoxicity and the acute toxicity experiments showed that the complex 1 was hypotonic and secure to organism. The study of complex 1 showed that the prepared complex on the basis of H2dipic and Met could inhibit hyperglycaemia and hyperlipidaemia in vivo and did not have potential toxicity. These results demonstrated that the complex 1 might provide an important reference for the development of functional hypoglycaemic foods or pharmaceuticals of T2DM.