| Abstract |
Vanadium is an essential element, which exists in all organisms at low concentration. Nevertheless, it plays a catalytic role in metalloenzymes like haloperoxidases and nitrogenases. Equally important, however, appear to be vanadium's multiple and complex roles as inorganic cofactor, sustaining diverse physiological activities in lower and higher organisms, including humans. Most notable among such activities are its antitumorigenicity, mitogenicity, and inhibition of key metabolic enzymes such as phosphoglucomutases and others. Outstanding among the various effects vanadium can exert is its ability to promote insulin mimetic activity in the pathophysiological state of diabetes mellitus in humans.
The wide spectrum of activities exhibited by vanadium undoubtedly arises as a result of complex interactions of the metal ion in its predominant oxidation states 4+ and 5+ with a plethora of high molecular as well as low molecular mass biomolecules. Of the low molecular mass bioligands interacting with vanadium are carboxylic acids, representative of which are citric acid and malic acid. The citric acid is present in human plasma at high concentration (0.1 mM), thus being capable of promoting interactions with various metal ions, like vanadium, potentially modulating a plethora of metabolic functions. Also another important physiological ligand is the hydrogen peroxide.
The way that was selected to be realised the study of interaction of vanadium with this molecules is the synthetic approach. Aim of this approach is the determination of soluble and bioavailable species, their complete structural, spectroscopy and potential characterization, and the cross-correlation of structural, spectroscopic attributes of these species with their potential biological action.
Therefore for the comprehension of biological action of vanadium, was studied a) the binary systems: V(IV)-citric acid, V(V)-Citric acid, and b) the ternary systems: V(V)-citric acid- hydrogen peroxide and V(V)-malic acid - hydrogen peroxide. From these studies were resulted vanadium species, that were characterized structurally, spectroscopically and electrochemically.
Moreover, for the vanadium V(IV, V)-citric acid and vanadium V(V)-citric acid-hydrogen peroxide systems, took place studies of the chemical reactivity of vanadium species as for a) the pH, b) the effect oxidant reagent and c) the effect of temperature. The results of this study were a) the connection of vanadium species of a system among them and b) the connection of different oxidation state vanadium species. Thus, it was resulted speciation diagram that shows how the vanadium species are converted as the pH changes and as the oxidation state of vanadium changes. Similar chemistry is likely to take place in the biological systems.
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