Publication Type
Journal Article
UWI Author(s)
Author, Analytic
Buglyó, P; Crans, D.C; Nagy, E.M; Lindo, R.L; Yang, L; Smee, J; Jin, W; Chi, L; Godzala III, M.E; Willsky, G.R
Author Affiliation, Ana.
Article Title
Aqueous Chemistry of the VanadiumIII (VIII) and the VIII-Dipicolinate Systems and a Comparison of the Effect of Three Oxidation States of Vanadium Compounds on Diabetic Hyperglycemia in Rats
Medium Designator
Connective Phrase
Journal Title
Inorganic Chemistry
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The aqueous vanadium(III) (VIII) speciation chemistry of two dipicolinate-type complexes and the insulin-enhancing effects of V-dipicolinate (V-dipic) complexes in three different oxidation states (VIII, VIV, and VV) have been studied in a chronic animal model system. The characterization of the VIII species was carried out at low ionic strength to reflect physiological conditions and required an evaluation of the hydrolysis of VIII at 0.20 M KCl. The aqueous VIII-dipic and VIII-dipic-OH systems were characterized, and complexes were observed from pH 2 to 7 at 0.2 M KCl. The VIII-dipic system forms stable 1:2 complexes, whereas the VIII-dipic-OH system forms stable 1:1 complexes. A comparison of these complexes with the V-pic system demonstrates that a second ligand has lower affinity for the VIII, presumably reflecting bidentate coordination of the second dipic2- to the VIII. The thermodynamic stability of the [VIII(dipic)2]- complex was compared to the stability of the corresponding VIV and VV complexes, and surprisingly, the VIII complexes were found to be more stable than anticipated. Oral administration of three V-dipicolinate compounds in different oxidation states {H[VIII(dipic)2H2O]·3H2O, [VIVOdipic(H2O)2]·2H2O, and NH4[VVO2dipic]} and the positive control, VOSO4, significantly lowered diabetic hyperglycemia in rats with streptozotocin-induced diabetes. The diabetic animals treated with the VIII- or VIV-dipic complexes had blood glucose levels that were statistically different from those of the diabetic group. The animals treated with the VV-dipic complex had the lowest blood glucose levels of the treated diabetic animals, which were statistically different from those of the diabetic group at all time points. Among the diabetic animals, complexation to dipic increased the serum levels of V after the administration of the VV and VIV complexes but not after the administration of the VIII complex when data are normalized to the ingested dose of V. Because V compounds differing only in oxidation state have different biological properties, it is implied that redox processes must be important factors for the biological action of V compounds. We observe that the VV-dipic complex is the most effective insulin-enhancing agent, in contrast to previous studies in which the VIV-maltol complex is the most effective. We conclude that the effectiveness of complexed V is both ligand and oxidation state dependent.....
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