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Speciation in the aqueous H+/H2VO4–/H2O2/picolinate system relevant to diabetes research
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
2004 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, no 3, 421-428 p.Article in journal (Refereed) Published
Abstract [en]

A detailed study of the quaternary aqueous H+/H2VO4/H2O2/picolinate (Pi) system has been performed at 25 °C in 0.150 M Na(Cl) medium using quantitative 51V NMR (500 MHz) and potentiometric data (glass electrode). In the ternary H+/H2VO4/Pi system, six complexes have been found in the pH region 1–10. In the quaternary H+/H2VO4/H2O2/Pisystem, eight additional complexes have been found. Generally, equilibria are fast in both systems. The rate of peroxide decomposition depends on the species in solution. Chemical shifts, compositions and formation constants for the species are given. Equilibrium conditions and the fit of the model to the experimental data are illustrated in distribution diagrams. Possible formation of mixed ligand species with imidazole, lactic acid and citric acid have been investigated and ruled out under the same experimental conditions. Structural proposals are given, based on 13C NMR data and available crystal structures.

Place, publisher, year, edition, pages
Cambridge: Royal Society of Chemistry, Thomas Graham House , 2004. no 3, 421-428 p.
URN: urn:nbn:se:umu:diva-4451DOI: 10.1039/B313424EOAI: diva2:143567
Available from: 2005-03-31 Created: 2005-03-31 Last updated: 2013-02-14Bibliographically approved
In thesis
1. Vanadate and Peroxovanadate Complexes of Biomedical Relevance: A speciation approach with focus on diabetes
Open this publication in new window or tab >>Vanadate and Peroxovanadate Complexes of Biomedical Relevance: A speciation approach with focus on diabetes
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Diabetes mellitus is one of the most threatening epidemics of modern times with rapidly increasing incidence. Vanadium and peroxovanadium compounds have been shown to exert insulin–like actions and, in contrast to insulin, are orally applicable. However, problems with side–effects and toxicity remain. The exact mechanism(s) by which these compounds act are not yet fully known. Thus, a better understanding of the aqueous chemistry of vanadates and peroxovanadates in the presence of various (bio)ligands is needed.

The present thesis summarises six papers dealing mainly with aqueous speciation in different vanadate – and peroxovanadate – ligand systems of biological and medical relevance. Altogether, five ligands have been studied, including important blood constituents (lactate, citrate and phosphate), a potential drug candidate (picolinic acid), and a dipeptide (alanyl serine) to model the interaction of (peroxo)vanadate in the active site of enzymes. Since all five ligands have been studied both with vanadates and peroxovanadates, the number of systems described in the present work is eleven, including the vanadate – citrate – lactate mixed ligand system. The pH–independent formation constants have been determined for 33 ternary vanadate – ligand, 41 quaternary peroxovanadate – ligand and two vanadate – mixed ligand species in addition to the pKa values of all five ligands. These constants have been used to model physiological conditions, and the biomedical relevance of the different species is discussed.

The studies have been performed at 25 ºC in the physiological medium of 0.150 M Na(Cl), i.e. the ionic strength of human blood. No buffers have been used, and wide pH–ranges have usually been covered. The applied experimental techniques comprise mostly 51V NMR and potentiometry, but 31P, 13C, 1H and 14N NMR as well as EPR and ESI–MS have also been used to gain additional information. Multimethod data have been treated by the least–squares program LAKE and modelling has been carried out by the software package WinSGW.

Whenever possible, solution structures of the species have been proposed. In addition, simple biological tests have been carried out to determine the stability of the formed peroxovanadate complexes in the presence of human catalase. A brief comparison is given of the different vanadate – ligand and peroxovanadate – ligand systems with emphasis on observed trends and general features.

Place, publisher, year, edition, pages
Umeå: Kemi, 2005. 74 p.
Inorganic chemistry, vanadium, hydrogen peroxide, lactate, citrate, phosphate, alanyl serine, picolinic acid, speciation, formation constants, equilibrium, solution structure, potentiometry, NMR (51V, 31P, 13C, 1H), Oorganisk kemi
National Category
Inorganic Chemistry
Research subject
Inorganic Chemistry
urn:nbn:se:umu:diva-489 (URN)91-7305-854-8 (ISBN)
Public defence
2005-04-22, KB3A9, KBC-huset, Umeå Universitet, Umeå, 13:00
Available from: 2005-03-31 Created: 2005-03-31 Last updated: 2012-06-26Bibliographically approved

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