Despite the fact that the physiological pathways are unclear, it is now known that vanadate has different pharmacokinetics compared to the decavanadate and therefore different pharmacological activities, although, in relation with the carbohydrate and lipid metabolism, these act very similar.
By contrast, metforminium decavanadate (MetfDeca) presented in Figure 1 showed an improvement in the intracellular biochemical behavior and also a recovering of the adequate levels of lipids and carbohydrates .
In this sense, the MetfDeca showed an important decrease of glycemia levels after 4 weeks of administration in the hyperglycemic alloxan-induced model, since decavanadate complexes have been described as insulin mimetics [6, 9-11, 23].
Protection on [beta] cell could be due to antioxidant feature that has been described, in which antioxidant stress markers as superoxide dismutase, catalase, and glutathione peroxidase are dependent on the nature of the polyoxovanadates present, besides the concentration administered, because higher levels of decavanadate can produce an increase of superoxide anion and cellular damage associated with Fenton-like reactions as it is observed in transitional elements [6, 23].
Insulin-mimetic attributes of decavanadate were challenged in two models with different metabolic disturbances, but with hyperglycemia in common.
The number of review papers and chapters reporting decavanadate biochemistry and biological activities has clearly increased since 2005 [1-5].
In the last years, our research group has performed novel in vivo studies with decavanadate in order to understand the contribution of decameric vanadate species to vanadium toxic effects [1, 10].
First of all, it was concluded that the effects induced by both vanadate and decavanadate depend not only on the concentration but also on other experimental parameters such as the exposure time, cellular fraction, type of tissue, mode of administration, and species of animal [1, 3, 10].
However, it is proposed that the mechanism for decavanadate detoxification is not the same, as it was suggested for the mechanism of thiol compounds oxidation by similar POMs .