Monosaccharides and the VO(IV) metao ion. Equilibrium, thermal studies and hypoglycemic effect

MARCELA GUIOTOKU; FATIMA REGINA MENA BARRETO SILVA; JOSÉ CARLOS AZZOLINI; ANA LUCIA RAMALHO MERCÉ; ANTONIO S MANGRICH; LUIS F SALA; BRUNO SZPOGANICZ,

POLYHEDRON

Elsevier

Lugar: Holanda; Año: 2007 vol. 26 p. 1269 - 1276

0277-5387

Protonation and complexation equilibrium of monosaccharides and the VO(IV) metal ion in aqueous solution were studied as well as their effect on the hyperglycemia of diabetic rats. The complexes formed were characterized by potentiometric titrations, paramagnetic resonance spectroscopy (EPR) and thermogravimetric-differential scnning calorimetry (TGA-DSC). The system involving D-gluconic acid (HGlu) and oxovanadioum(IV) (VO2+) was chosen to study the serum goucose levels in alloxan-induced diabetic rats. A binuclear species was detected in samll quantities, which was formed by coordination of two HGlu molecules and two VO2+ ions through a hydroxide bridge. The mononuclear species formed byh HGlu and VO2+ were confirmed by EPR. The anisotropic spectra obtained from aqueous frozen solutions (77K) are characteristic of mononuclear VO-hexoses. The cyclic sugars D-ribone-1,4-lactone(Riblac), D-galactone-1,4-lactone(Galac) and 2-deoxy-D-glucopyranose(dGlu) shoed weak interaction with the metal ion and they are not able to hold the metal in solution above pH 4.6 resulting in hydrolysis of the metal ion. Also, the acute treatment with sugar complexes of HGlu-VO led to a significant hypoglycemic effect(23% and 18% by intraperitoneal or oral gavage treatment respectively) in diabetic rats. These results show the potential effectiveness of VO-HGlu complexes agents through intraperitoneal injection in alloxan-induced diabetic rats.