Vanadium Detoxification: Chemical and Biochemical Aspects

Abstract

1. Introduction. -The biological effects, biodistribution, pharmacological activity, and toxicology of vanadium are areas of increasing research interest. Although numerous biochemical and physiological functions have been suggested for this element, and despite the amount of the knowledge so far accumulated, vanadium still does not have a clearly defined role in the higher forms of life [1 -5].So far, the best evidence for a biological role of vanadium comes from bacteria (the so-called alternative nitrogenases in which vanadium replaces molybdenum in the FeMo-cofactor of some Azotobacter species) [ Environmental contamination by vanadium has dramatically increased during the last decades, especially in the most developed countries, due to the widespread use of fossil fuels, many of which liberate finely particulate V 2 O 5 to the atmosphere during combustion [13 -15]. Therefore, and also owing to the emerging interest in the pharmacological effects of some of its compounds [16 -20], the toxicology and detoxification of vanadium constitute areas of increasing research interest. The older literature about vanadium toxicology has been reviewed in the classical work of Faulkner-Hudson [21], and we have analyzed the most relevant aspects of its detoxification some years ago [22]. The pertinent information is extended and updated in the present review.Vanadium toxicity has been reported in experimental animals and in humans. The degree of toxicity depends on the route of incorporation, valence, and chemical form of the element, and is also, to some extent, species-dependent [21] [22]. In general, it increases as valence increases, pentavalent vanadium being the most toxic [22] [23]. Although, under normal natural conditions, toxic effects do not occur frequently, at high doses or as a consequence of chronic exposure, it is a relatively toxic element for humans [24].The upper respiratory tract is the main target in occupational exposure. Vanadium compounds, especially V 2 O 5 , are strong irritants of the airways and eyes. Acute and

Transcriptional and posttranscriptional regulation of CYP1A1 by vanadium in human hepatoma HepG2 cells

“…This feature of TCDD is responsible for its accumulation in the food and its sustained effects on animal and human health (Schuetz et al 1995;Stapleton and Baker 2003). Environmental contamination by vanadium has dramatically increased during the last decades, especially in the most developed countries due to the widespread use of fossil fuels, many of which liberate fine particulates of V 5+ to the atmosphere during combustion (Baran 2008). Humans consume appreciable amounts of V 5+ in food and water (Evangelou 2002).…”

Selenium interactions and toxicity: a review

“…The dietary vanadium intake is estimated to be in the range of 0.01-0.02 mg per day (ATSDR 2009). The element is distributed mainly to the liver, kidney, spleen and finally to the bone (Baran 2008). A detailed, biological role of V has not been established yet.…”

Lipid peroxidation in the liver of rats treated with V and/or Mg in drinking water

“…It has been generally accepted that imbalance between the generation of free radicals and the antioxidant potential of the organism results in oxidative stress and that overproduction of ROS impairs the capacity of the antioxidant defense system (Bartosz, 2004). It is also well known that vanadate is eff ectively reduced to vanadyl (VO 2+ ) in the cells in the presence of L-ascorbic acid, glutathione (GSH) and cysteine, involved in its biological detoxifi cation (Baran, 2008). One-electron reduction of intracellular vanadate by ascorbate has been suggested to represent an important vanadium reduction pathway in vivo, taking into account the fact that ascorbate is present at relatively high concentrations in the cellular system (Ding et al, 1994).…”