Toxicity of Nanocomplexes Containing Gadolinium Orthovanadate Nanoparticles and Cholesterol.

Previous studies have shown the ability of nanocomplexes (NCs), which consist of nanoparticles (NPs) of orthovanadates of rare earth metals (GdYVO4:Eu3+) and cholesterol, to inhibit the growth of Ehrlich's ascites carcinoma (EAC). However, the biosafety of these NCs remains unclear. Our objective was to investigate the acute and subchronic toxicity of NCs. NCs were administered to BALB/c mice in NPs concentration of 5.9; 29.5; 59.1; and 118.2 mg/kg. Acute toxicity was induced by a single administration of NCs, subchronic-by repeated daily administration of NCs for 14 days. On day 15 and on day 31 for acute and subchronic toxicity, respectively, the percentage of animal survival, body weight, condition of visceral organs, and activities of γ-glutamyl transferase (GGT) and glucose-6-phosphate dehydrogenase (G-6-PDH) were determined. It was found that administration of NCs in the concentration of 5.9 mg/kg and 29.5 mg/kg of NPs did not influence on survival of animals or have a negative impact on their performance status, morphological and quantitative characteristics of visceral organs, and activities of the GGT and G-6-PDH in the liver. For acute toxicity, the semi-lethal dose (LD50) of nanocomplexes was determined (118.2 mg/kg of NPs). As to subchronic toxicity, it was found that repeated (for 14 days) administration of NCs containing 59.1 mg/kg of NPs decrease survival of animals to 50%. The coefficient of accumulation (Cacum = 7) indicates the low accumulative ability of NCs upon long-term use. Thus, from the LD50 and accumulation coefficient, NCs can be referred to as low-toxic substances and used in conditionally therapeutic doses in oncological practice to develop nanostructured formulations of drugs.

Effects of vanadium (sodium metavanadate) and aflatoxin-B1 on cytochrome p450 activities, DNA damage and DNA methylation in human liver cell lines.

Vanadium is considered as "possibly carcinogenic to humans" (V2O5, IARC Group 2B), yet uncertainties persist related to the toxicity mechanisms of the multiple forms of vanadium. Exposure to vanadium often co-occurs with other metals or with organic compounds that can be transformed by cytochrome p450 (CYP) enzymes into DNA-reactive carcinogens. Therefore, effects of a soluble form of vanadium (sodium metavanadate, NaVO3) and aflatoxin-B1 (AFB1) were tested separately and together, for induction of CYP activities, DNA damage (γH2AX and DNA alkaline unwinding assays), and DNA methylation changes (global genome and DNA repeats) in HepaRG or HepG2 liver cell lines. NaVO3 (≥ 2.3 µM) reduced CYP1A1 and CYP3A4 activities and induced DNA damage, butcaused important cell proliferation only in HepaRG cells. As a binary mixture, NaVO3 did not modify the effects of AFB1. There was no reproducible effect of NaVO3 (<21 µM) on DNA methylation in AluYb8, satellite-α, satellite-2, and by the luminometric methylation assay, but DNA methylation flow-cytometry signals in HepG2 cells (25-50 µM) increased at the G1 and G2 cell cycle phases. In conclusion, cell lines responded differently to NaVO3 supporting the importance of investigating more than one cell line, and a carcinogenic role of NaVO3 might reside at low concentrations by stimulating the proliferation of tumorigenic cells.

In vitro study of the protective effect of manganese against vanadium-mediated nuclear and mitochondrial DNA damage.

We aimed to study the effect of vanadium(V) exposure on cell viability, nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) and to elucidate if these effects can be reverted by co-exposure to V and manganese (Mn). HepG2 cells were incubated with various concentrations of bis(maltolato)oxovanadium(IV) or MnCl2 for 32 h for viability study. The higher concentrations (59   µM V, 54 nM Mn and 59   µM V+54 nM Mn) were used to study DNA damage and uptake of V and Mn. Comet assay was used for the study of nDNA damage; mtDNA damage was studied by determining deletions and number of copies of the ND1/ND4 mtDNA region. Cellular content of V and Mn was determined using ICPMS. Cellular exposure to 59   µM V decreased viability (14%) and damaged nDNA and mtDNA. This effect was partially prevented by the co-exposure to V + Mn. Exposure to V increased the cellular content of V and Mn (812.3% and 153.5%, respectively). Exposure to Mn decreased the content of V and Mn (62% and 56%, respectively). Exposure to V + Mn increased V (261%) and decreased Mn (56%) content. The positive effects on cell viability and DNA damage when incubated with V + Mn could be due to the Mn-mediated inhibition of V uptake.

Vanadium Derivative Exposure Promotes Functional Alterations of VSMCs and Consequent Atherosclerosis via ROS/p38/NF-κB-Mediated IL-6 Production.

Vanadium is a transition metal widely distributed in the Earth's crust, and is a major contaminant in fossil fuels. Its pathological effect and regulation in atherosclerosis remain unclear. We found that intranasal administration of the vanadium derivative NaVO3 significantly increased plasma and urinary vanadium levels and induced arterial lipid accumulation and atherosclerotic lesions in apolipoprotein E-deficient knockout mice (ApoE-/-) murine aorta compared to those in vehicle-exposed mice. This was accompanied by an increase in plasma reactive oxygen species (ROS) and interleukin 6 (IL-6) levels and a decrease in the vascular smooth muscle cell (VSMC) differentiation marker protein SM22α in the atherosclerotic lesions. Furthermore, exposure to NaVO3 or VOSO4 induced cytosolic ROS generation and IL-6 production in VSMCs and promoted VSMC synthetic differentiation, migration, and proliferation. The anti-oxidant N-acetylcysteine (NAC) not only suppresses IL-6 production and VSMC pathological responses including migration and proliferation but also prevents atherosclerosis in ApoE-/- mice. Inhibition experiments with NAC and pharmacological inhibitors demonstrated that NaVO3-induced IL-6 production is signaled by ROS-triggered p38-mediated NF-κB-dependent pathways. Neutralizing anti-IL-6 antibodies impaired NaVO3-mediated VSMC migration and proliferation. We concluded that NaVO3 exposure activates the ROS-triggering p38 signaling to selectively induce NF-κB-mediated IL-6 production. These signaling pathways induce VSMC synthetic differentiation, migration, and proliferation, leading to lipid accumulation and atherosclerosis.

Vanadium compounds and cellular death mechanisms in the A549 cell line: The relevance of the compound valence.

Non-small lung cell carcinoma has a high morbidity and mortality rates. The elective treatment for stage III and IV is cisplatinum that conveys serious toxic side effects. Vanadium compounds are metal molecules with proven antitumor activity that depends on its valence. Therefore, a better understanding of the mechanism of action of vanadium compounds is required. The aim of our study was to investigate the mechanisms of cell death induced by sodium metavanadate (NaVO3 [V(+5)]) and vanadyl sulfate (VOSO4 [(+4)]), both of which have reported apoptotic-inducing activity. We exposed the A549 cell line to various concentrations (0-100 µM) and to different exposure times to each compound and determined the cell viability and expression of caspases, reactive oxygen species (ROS) production, Bcl2, Bax, FasL and NO. Our results showed that neither compounds modified the basal expression of caspases or pro- and anti-apoptotic proteins. The only change observed was the 12- and 14-fold significant increase in ROS production induced by NaVO3 and VOSO4 , respectively, at 100 µm concentrations after 48 hours. Our results suggest that classical apoptotic mechanisms are not related to the cell death induced by the vanadium compounds evaluated here, and showed that the higher ROS production was induced by the [(+4)] valence compound. It is possible that the difference will be secondary to its higher oxidative status and thus higher ROS production, which leads to higher cell damage. In conclusion, our results suggest that the efficacy of the cell death mechanisms induced by vanadium compounds differ depending on the valence of the compound.

Resveratrol Ameliorates Tau Hyperphosphorylation at Ser396 Site and Oxidative Damage in Rat Hippocampal Slices Exposed to Vanadate: Implication of ERK1/2 and GSK-3ß Signaling Cascades.

The objective of this study was to investigate the effect of resveratrol (a natural polyphenolic phytostilbene) on tau hyperphosphorylation and oxidative damage induced by sodium orthovanadate (Na3VO4), the prevalent species of vanadium (vanadate), in rat hippocampal slices. Our results showed that resveratrol significantly inhibited Na3VO4-induced hyperphosphorylation of tau at the Ser396 (p-S396-tau) site, which is upregulated in the hippocampus of Alzheimer's disease (AD) brains and principally linked to AD-associated cognitive dysfunction. Subsequent mechanistic studies revealed that reduction of ERK1/2 activation was involved in the inhibitory effect of resveratrol by inhibiting the ERK1/2 pathway with SL327 mimicking the aforementioned effect of resveratrol. Moreover, resveratrol potently induced GSK-3ß Ser9 phosphorylation and reduced Na3VO4-induced p-S396-tau levels, which were markedly replicated by pharmacologic inhibition of GSK-3ß with LiCl. These results indicate that resveratrol could suppress Na3VO4-induced p-S396-tau levels via downregulating ERK1/2 and GSK-3ß signaling cascades in rat hippocampal slices. In addition, resveratrol diminished the increased extracellular reactive oxygen species generation and hippocampal toxicity upon long-term exposure to Na3VO4 or FeCl2. Our findings strongly support the notion that resveratrol may serve as a potential nutraceutical agent for AD.

Vanadium toxicity in the thymic development.

The purpose of this study was to define the toxic effects of vanadium on thymic development in broilers fed on diets supplemented with 0, 5, 15, 30, 45 and 60 mg/kg of vanadium for 42 days. We examined the changes of relative weigh, cell cycle phase, apoptotic cells, and protein expression of Bcl-2, Bax, and caspase-3 in the thymus by the methods of flow cytometry, TUNEL (terminal-deoxynucleotidyl transferase mediated nick end labeling) and immunohistochemistry. The results showed that dietary high vanadium (30 mg/kg, 45 mg/kg and 60 mg/kg) caused the toxic effects on thymic development, which was characterized by decreasing relative weigh, increasing G0/G1 phase (a prolonged nondividing state), reducing S phase (DNA replication) and proliferating index (PI), and increasing percentages of apoptotic thymocytes. Concurrently, the protein expression levels of Bax and caspase-3 were increased, and protein expression levels of Bcl-2 were decreased. The thymic development suppression caused by dietary high vanadium further leads to inhibitive effects on T lymphocyte maturity and activity, and cellular immune function. The above-mentioned results provide new evidences for further understanding the vanadium immunotoxicity. In contrast, dietary 5 mg/kg vanadium promoted the thymic development by increasing relative weigh, decreasing G0/G1 phase, increasing S phase and PI, and reducing percentages of apoptotic thymocytes when compared to the control group and high vanadium groups.

Pituitary Adenylate Cyclase-Activating Polypeptide Reverses Ammonium Metavanadate-Induced Airway Hyperresponsiveness in Rats.

The rate of atmospheric vanadium is constantly increasing due to fossil fuel combustion. This environmental pollution favours vanadium exposure in particular to its vanadate form, causing occupational bronchial asthma and bronchitis. Based on the well admitted bronchodilator properties of the pituitary adenylate cyclase-activating polypeptide (PACAP), we investigated the ability of this neuropeptide to reverse the vanadate-induced airway hyperresponsiveness in rats. Exposure to ammonium metavanadate aerosols (5 mg/m(3)/h) for 15 minutes induced 4 hours later an array of pathophysiological events, including increase of bronchial resistance and histological alterations, activation of proinflammatory alveolar macrophages, and increased oxidative stress status. Powerfully, PACAP inhalation (0.1 mM) for 10 minutes alleviated many of these deleterious effects as demonstrated by a decrease of bronchial resistance and histological restoration. PACAP reduced the level of expression of mRNA encoding inflammatory chemokines (MIP-1α, MIP-2, and KC) and cytokines (IL-1α and TNF-α) in alveolar macrophages and improved the antioxidant status. PACAP reverses the vanadate-induced airway hyperresponsiveness not only through its bronchodilator activity but also by counteracting the proinflammatory and prooxidative effects of the metal. Then, the development of stable analogs of PACAP could represent a promising therapeutic alternative for the treatment of inflammatory respiratory disorders.

Cyclooxygenase-1 as the main source of proinflammatory factors after sodium orthovanadate treatment.

Vanadium is a metal present in air pollution. Its compounds may have both anticancer and carcinogenic properties. Vanadium compounds are tested in treatment of diabetes and cancer. An important research direction aimed at better understanding of the mechanisms of action of the vanadium compounds is a more detailed insight into their impact on inflammatory reactions. The aim of this study was to examine the effect of micromolar concentrations of sodium orthovanadate, Na3VO4, on the activity and expression of cyclooxygenases: COX-1 and COX-2. PMA-activated THP-1 macrophages were incubated in vitro for 48 h with micromolar concentrations of sodium orthovanadate. As shown by an ELISA assay, sodium orthovanadate increases the quantity of prostaglandin E2 being released into the medium in a dose-dependent manner as well as impacts the quantity of the stable metabolite of thromboxane A2: thromboxane B2. The use of a COX-2 inhibitor, NS-398, revealed that this effect was independent of changes in the activity of COX-2. Western blotting analysis showed that sodium orthovanadate increased the expression of COX-2 when used with NS-398. Quantitative real-time PCR measurements of mRNA levels of genes PTGS1 and PTGS2 revealed no effect of the tested vanadium compound on the levels of analyzed transcripts.

Exposure to bis(maltolato)oxovanadium(IV) increases levels of hepcidin mRNA and impairs the homeostasis of iron but not that of manganese.

The aim of this study was to examine whether alterations in iron homeostasis, caused by exposure to vanadium, are related to changes in the gene expression of hepatic hepcidin. Two groups of rats were examined: control and vanadium-exposed. Vanadium, as bis(maltolato)oxovanadium(IV) was supplied in the drinking water. The experiment had a duration of five weeks. Iron and manganese were measured in excreta, serum and tissues. Leptin, ferritin, IL-1ß, IL-6, TNF-α, red blood cells, haemoglobin and haematocrit were determined. Protein carbonyl group levels and hepcidin gene expression were determined in the liver. In the vanadium-exposed rats, iron absorption, serum iron and leptin and all haematological parameters decreased. Levels of IL-6, TNF-α and ferritin in serum and of iron in the liver, spleen and heart increased. In the liver, levels of protein carbonyl groups and hepcidin mRNA were also higher in the vanadium-exposed group. Exposure to vanadium did not modify manganese homeostasis. The results obtained from this study provide the first evidence that bis(maltolato)oxovanadium(IV) produces an increase in the gene expression of the hepcidin, possibly caused by an inflammatory process. Both factors could be the cause of alterations in Fe homeostasis and the appearance of anaemia. However, Mn homeostasis was not affected.

Vanadate from air pollutant inhibits hrs-dependent endosome fusion and augments responsiveness to toll-like receptors.

There is a well-established association between exposure to air pollutants and pulmonary injuries. For example, metals found in ROFA (residual oil fly ash) increase susceptibility of mice as well as humans to microbial infections. In our research, we have found that vanadate substantially increased the response of several Toll-like receptors (TLRs) to stimulation with their ligands. Although vanadate caused generation of reactive oxygen species (ROS), the addition of ROS scavenger N-acetyl cysteine (NAC) had no effect on augmented lipopolysaccharide (LPS) stimulation. We further showed that vanadate inhibits endosome fusion. This effect was determined by measuring the size of endosomes, NF-κB activity and TLR4 degradation in Hrs (hepatocyte growth factor-regulated tyrosine kinase substrate) overexpressed cells. Moreover, we identified the role of Hrs phosphorylation in these processes. Based on our findings, we can conclude that vanadate potentiates TLR4 activity by increasing Hrs phosphorylation status, reducing the size of Hrs/TLR4-positive endosomes and impacting TLR4 degradation, thus contributing to the detrimental effects of air pollutants on human health.

The renal effects of vanadate exposure: potential biomarkers and oxidative stress as a mechanism of functional renal disorders--preliminary studies.

The alterations in the levels/activities of selected biomarkers for detecting kidney toxicity and in the levels of some oxidative stress (OS) markers and elements were studied in male rats to evaluate biochemically the degree of kidney damage, investigate the role of OS in the mechanism of functional renal disorders, reveal potential biomarkers of renal function, and assess the renal mineral changes in the conditions of a 12-week sodium metavanadate (SMV, 0.125 mg V/mL) exposure. The results showed that OS is involved in the mechanism underlying the development of SMV-induced functional renal disturbances. They also suggest that the urinary cystatin C (CysCu) and kidney injury molecule-1 (KIM-1u) could be the most appropriate to evaluate renal function at the conditions of SMV intoxication when the fluid intake, excreted urinary volume (EUV), body weight (BW), and the urinary creatinine excretion (Creu) decreased. The use of such tests as the urinary lactate dehydrogenase, alkaline phosphatase, γ-glutamyltranspeptidase, and N-acetyl-ß-D-glucosaminidase (LDHu, ALPu, GGTPu, and NAGu) seems not to be valid given their reduced activities. The use of only traditional biomarkers of renal function in these conditions may, in turn, be insufficient because their alterations are greatly influenced by the changes in the fluid intake and/or BW.

The influence of combined magnesium and vanadate administration on the level of some elements in selected rat organs: V-Mg interactions and the role of iron-essential protein (DMT-1) in the mechanism underlying altered tissues iron level.

The effect of 12 week co-administration of sodium metavanadate (SMV) and magnesium sulfate (MS) on the levels of some elements in selected rats' organs and an attempt to elucidate a role of divalent metal transporter 1 (DMT-1) in the mechanism(s) of the SMV-induced disorders in some tissue Fe homeostasis were studied. SMV taken up separately or in combination with MS may pose a risk of the rise and shortage of the total hepatic and splenic Fe and Cu contents, respectively, cerebral Fe deficiency, splenic Ca deposition, and the hepatic, renal, and cerebral DMT-1 down-regulation. When administered alone, SMV may also cause the decrease in the total renal Fe and Cu contents. A visible protective effect of Mg against the renal and cerebral V accumulation and the decrease in the renal Fe and Cu contents during the SMV-MS co-administration together with our previous findings suggest a beneficial role of Mg at SMV exposure. Further, the SMV-induced fall in total iron binding capacity (TIBC), reported previously, and its correlations with the hepatic, splenic, and cerebral Fe levels allow us to suggest that diminished TIBC could be partly involved in the mechanism(s) responsible for the dramatic redistribution of Fe in those tissues. Finally, DMT-1, which potentially could participate in the hepatic non-transferrin Fe-bound uptake, does not play a significant role in this process indicating the need for studying other Fe transporters to more precisely elucidate molecular mechanism(s) underlying the hepatic Fe loading in our experimental conditions.

Sodium metavanadate exhibits carcinogenic tendencies in vitro in immortalized human bronchial epithelial cells.

Pentavalent vanadium compounds induce intracellular changes in vitro that are consistent with those of other carcinogenic substances. While there is no clear evidence that vanadium compounds cause cancer in humans, vanadium pentoxide causes lung cancer in rodents after long-term inhalation exposures and in turn IARC has categorized it as a group 2B possible human carcinogen. The goal of this study was to investigate the carcinogenicity of NaVO3 in the human immortalized bronchial epithelial cell line, Beas-2B. Cells were treated with 10 µM NaVO3 for 5 weeks, with or without recovery time, followed by gene expression microarray analysis. In a separate experiment, cells were exposed to 1-10 µM NaVO3 for 4 weeks and then grown in soft agar to test for anchorage-independent growth. A dose-dependent increase in the number of colonies was observed. In scratch tests, NaVO3-transformed clones could repair a wound faster than controls. In a gene expression microarray analysis of soft agar clones there were 2010 differentially expressed genes (DEG) (adjusted p-value ≤ 0.05) in NaVO3-transformed clones relative to control clones. DEG from this experiment were compared with the DEG of 5 week NaVO3 exposure with or without recovery, all with adjusted p-values < 0.05, and 469 genes were altered in the same direction for transformed clones, 5 week NaVO3-treated cells, and the recovered cells. The data from this study imply that chronic exposure to NaVO3 causes changes that are consistent with cellular transformation including anchorage-independent growth, enhanced migration ability, and gene expression changes that were likely epigenetically inherited.

Effects of sodium metavanadate on in vitro neuroblastoma and red blood cells.

Toxicity of vanadium on cells is one of the less studied effects. This prompted us to study the structural effects induced on neuroblastoma and erythrocytes by vanadium (V) sodium metavanadate. This salt was incubated with mice cholinergic neuroblastoma cells and intact human erythrocytes. To learn whether metavanadate interacts with membrane lipid bilayers it was incubated with bilayers built-up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE). These are phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. Exposure of neuroblastoma cells to metavanadate showed significant decreases in cell viability as well as in cell number correlating with inhibition of aconitase activity. In scanning electron microscopy (SEM) and defocusing microscopy (DM) it was observed that induced on erythrocytes the formation of echinocytes. However, no effects were obtained when metavanadate was made to interact with DMPC and DMPE multibilayers and liposomes, assays performed by X-ray diffraction and differential scanning calorimetry (DSC), respectively. These results imply that the effects of metavanadate on erythrocytes are through interactions with proteins located in the membrane outer moiety, and could still involve other minor lipid components as well. Also, partly unsaturated lipids could interact differently the fully saturated chains in the model systems.

A multifunctional biphasic suspension of mesoporous silica encapsulated with YVO4:Eu3+ and Fe3O4 nanoparticles: synergistic effect towards cancer therapy and imaging.

Polyol mediated synthesized luminescent YVO(4):Eu(3+) nanoparticles (NPs) have been encapsulated in mesoporous silica nanoparticles (MSNs) using the sol-gel process. X-ray diffraction and Fourier transform infrared spectroscopy along with transmission electron microscopy confirm the encapsulation of the YVO(4):Eu(3+) NPs in the SiO(2) matrix. N(2) adsorption/desorption analysis confirms the mesoporous nature of the MSNs and YVO(4):Eu(3+)-MSNs. No significant quenching of the YVO(4):Eu(3+) luminescence is observed for YVO(4):Eu(3+)-MSNs. This nanocomposite has been tested as a potential drug carrier. Efficient loading of doxorubicin hydrochloride (DOX), a typical anticancer drug, is observed which reaches up to 93% in 8 mg ml(-1) of YVO(4):Eu(3+)-MSNs. pH sensitive release of DOX is observed, with 54% release for pH 4.3 and 31% in a physiological environment (pH 7.4). Both MSNs and YVO(4):Eu(3+)-MSNs nanocomposites do not show accountable toxicity to two cell lines, i.e. HeLa and MCF-7. However, as desired, toxicity is observed when cells are incubated with DOX loaded YVO(4):Eu(3+)-MSNs. Laser scanning confocal microscopy images confirm the uptake of the nanocomposite in both cell lines. The morphology of the cells (MCF-7) changes after incubation with DOX loaded YVO(4):Eu(3+)-MSNs, indicating an interaction of DOX with the cells. More cytotoxicity to both cell lines with ∼90% killing is observed due to the synergistic effect of magnetic fluid hyperthermia and chemotherapy using a biphasic suspension of superparamagnetic iron oxide magnetic nanoparticles and DOX loaded YVO(4):Eu(3+)-MSNs. In addition, an AC magnetic field triggers an enhanced drug release.

Vanadium toxicity in mice: possible impairment of lipid metabolism and mucosal epithelial cell necrosis in the small intestine.

Because precise information as to the toxicity of vanadium is required for practical use of vanadium compounds as antidiabetic drugs, we examined vanadium toxicity in mice fed normal diet or high-fat diet (C57BL/6N, male, 7 weeks) by oral administration of ammonium metavanadate (AMV) with a maximum dose of 20 mgV/kg/day. Marked lipid accumulation in hepatocytes, renal epithelial cells, and mucosal epithelial cells of the small and large intestines and severe degeneration, necrosis, and loss of mucosal epithelial cells in the small intestine were observed. These pathological changes were more severe in mice fed high-fat diet than mice fed normal diet, and the intensity of the changes increased with increase in the administered dose of AMV. By electron microscopy, the number and size of lipid droplets in hepatocytes were increased. In the small intestine, a TUNEL assay showed a decreased number of positive cells, and positive cells for acrolein immunohistochemistry were observed specifically in the mucosal epithelial cells indicating degeneration and necrosis in the AMV-treated group, suggesting that a possible factor responsible for cell necrosis in the small intestine could be oxidative stress. In conclusion, AMV may impair cellular lipid metabolism, resulting in lipid accumulation, and induce mucosal epithelial cell necrosis in the small intestine.

Hydroxylamido-amino acid complexes of oxovanadium(V). Toxicological study in cell culture and in a zebrafish model.

Oxovanadium(V) complexes [VO(NH(2)O)(2)(val)] and [VO(NH(2)O)(2)(met)] caused inhibition of cell proliferation in two osteoblast cell lines, MC3T3-E1 and UMR106, as well as the viability of zebrafish eggs. In MC3T3-E1, both compounds inhibited cell proliferation (up to ca. 40% at 25 µM [VO(NH(2)O)(2)(val)] and 25% at 25 µM [VO(NH(2)O)(2)(met)]). This effect occurs in a dose response manner from 2.5 µM (p < 0.01) with a more deleterious action of [VO(NH(2)O)(2)(met)]. In UMR106 tumoral cells, [VO(NH(2)O)(2)(val)] inhibited cell proliferation up to 75% from 25 µM while [VO(NH(2)O)(2)(met)] behaved as an inhibitory agent in the whole range of concentrations (p < 0.01). Similar toxic effects were obtained from morphological studies in cell cultures. Moreover, the IC(50) values for both complexes in culture studies correlated with the IC(50) values obtained with an in vivo model of toxicity (FET test). Besides, the cytotoxicity evaluation in cell culture showed a decrease in mitochondrial activity which was stronger for [VO(NH(2)O)(2)(met)] than for [VO(NH(2)O)(2)(val)] (44% vs. 58% at 25 µM) in both cell lines (p < 0.001). Genotoxicity assessed by micronuclei induction also showed a stronger effect of [VO(NH(2)O)(2)(met)] in both cell lines. Besides, [VO(NH(2)O)(2)(val)] caused DNA damage determined by comet formation in MC3T3-E1 cells in the range of 2.5-25 µM, while this effect could not be observed in the osteosarcoma cells. On the other hand, [VO(NH(2)O)(2)(val)] enhanced ROS levels over basal up to 225% and 170% at 100 µM in MC3T3-E1 and UMR106 cells, respectively (p < 0.01). For [VO(NH(2)O)(2)(met)] a similar situation was observed, suggesting an important role for oxidative stress in the toxicity mechanism of action. Although both complexes showed interesting results that would deserve further drug development [VO(NH(2)O)(2)(val)] was more stable than [VO(NH(2)O)(2)(met)] in the solid state. Therefore, we consider that [VO(NH(2)O)(2)(val)] is a good candidate to be tested in in vivo models as a potential antitumoral agent.

Evaluation of the interaction of vanadium with glutathione in human blood components.

Metallo-elements including Vanadium (V) have strong affinity for sulfhydryl (-SH) groups in biological molecules including Glutathione (GSH) in tissues. Because of this fact it was of interest to further investigate the interaction of Ammonium Vanadate [NH(4)VO(3)] with Glutathione as a biomarker of toxicity and the role of Glutathione in the detoxification and conjugation pr(o)Cesses in whole blood components including plasma and cytosolic fraction. Effects of different concentrations of Ammonium Vanadate [NH(4)VO(3)] on the level of reduced Glutathione in whole blood components (Plasma and Cytosolic fraction) were examined. GSH depletion in plasma and cytosolic fraction was Ammonium Vanadate's concentration-dependent. Depleted GSH level was more pronounced with more incubation time period. These findings show that changes in the GSH status produced by Ammonium Vanadate could be due to either by adduct formation of Vanadium and glutathione i.e. (V-SG) or by increased production of oxidized Glutathione (2GSH +V(+5) → GSSG). This change in GSH metabolic status provides some information regarding the mechanism of toxicity by Ammonium Vanadate and the protective role of glutathione.

Effect of 12-week vanadate and magnesium co-administration on chosen haematological parameters as well as on some indices of iron and copper metabolism and biomarkers of oxidative stress in rats.

Changes in some blood parameters after 12-week administration of sodium metavanadate (SMV; 0.125mgV/ml) or/and magnesium sulphate (MS; 0.06mgMg/ml) in drinking water were studied in outbred male Wistar rats (16 rats/each group) to explore the probable mechanism(s) underlying SMV toxicity and check whether Mg at the level selected during SMV co-administration can protect, at least in part, from a possible deleterious action of SMV. Exposure to SMV alone and in combination with MS (a) led to a decrease in fluid and food intake and body weight gain; (b) predisposed the animals to the development of microcytic-hypochromic anaemia (with excessive liver and spleen Fe deposition, unaltered plasma Fe level and enhanced Zn concentration in the erythrocytes (RBCs) characterized by a reduced haematocrit (Ht) index and haemoglobin (Hb) level, unchanged erythrocyte and reticulocyte count, anisocytosis, lowered total iron binding capacity (TIBC) and elevated transferrin saturation (TS); (c) disturbed Cu homeostasis, but (d) did not influence the leukocyte count and the plasma total antioxidant status (TAS). We suggest that abnormal metabolism and accumulation of Fe as well as an altered Cu status and the RBC Zn level might lead to defective Fe utilization and be a factor promoting the development of Fe-utilization anaemia. The disturbances in the antioxidative capacity reported previously in rats' RBCs after SMV intoxication (Scibior, Zaporowska, Environ. Toxicol. Pharmacol. 30 (2010) 153-161) may suggest that oxidative stress (OS) could also be, in part, involved in the mechanism responsible for the development of anaemia. The Mg dose ingested in combination with V under SMV-MS co-administration (a) was able to decrease, to some extent, the V concentration in the blood, (b) normalized the RBC Mg and Fe levels and (c) restored the values of some parameters of the Fe status near the control values. These results allow a supposition that a higher Mg dose consumed during SMV exposure could have better protective potential and be more effective in limiting the SMV toxicity observed.