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PubMed2006

The permeability and cytotoxicity of insulin-mimetic vanadium (III,IV,V)-dipicolinate complexes.

Vanadium (III,IV,V)-dipicolinate complexes with different redox properties were selected to investigate the structure-property relationship of insulin-mimetic vanadium complexes for membrane permeability and gastrointestinal (GI) stress-related toxicity using the Caco-2 cell monolayer model. The cytotoxicity of the vanadium complexes was assayed with 3-(4,5-dimethylthiazoyl-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assays and the effect on monolayer integrity was measured by the trans-epithelial electric resistance (TEER). The three vanadium complexes exhibited intermediate membrane permeability (P(app) = 1.4-3.6x10(-6) cm/s) with low cellular accumulation level (<1%). The permeability of all compounds was independent of the concentration of vanadium complexes and excess picolinate ligands. Both V(III) and V(V)-dipicolinate complexes induced 3-4-fold greater reactive oxygen and nitrogen species (RONS) production than the V(IV)-dipicolinate complex; while the vanadium (III)-dipicolinate was 3-fold less damaging to tight junction of the Caco-2 cell monolayer. Despite the differences in apparent permeability, cellular accumulation, and capacity to induce reactive oxygen and nitrogen species (RONS) levels, the three vanadium complexes exhibited similar cytotoxicity (IC50 = 1.7-1.9 mM). An ion pair reagent, tetrabutylammonium, increased the membrane apparent permeability by 4-fold for vanadium (III and IV)-dipicolinate complexes and 16-fold for vanadium (V)-dipicolinate as measured by decrease in TEER values. In addition, the ion pair reagent prevented damage to monolayer integrity. The three vanadium (III,IV,V)-dipicolinate complexes may pass through caco-2 monolayer via a passive diffusion mechanism. Our results suggest that formation of ion pairs may influence compound permeation and significantly reduce the required dose, and hence the GI toxicity of vanadium-dipicolinate complexes.

Caco-2 Cells↗
PubMed2004

Inhibition of DNA alkylation damage with inorganic salts.

Human exposure to alkylating agents metabolized from tobacco- and food-borne carcinogens occurs regularly. Dietary inorganic compounds such as selenium and vanadium have been shown previously to provide chemoprotective benefits in rat and human trials. Here, we present biochemical data on the ability of inorganic compounds to protect DNA from alkylation damage. An enzyme cleavage assay is used to observe alkylated DNA. Simple salts (e.g., NaCl or NiCl(2)) did not prevent DNA alkylation, whereas anionic oxo species (e.g., Na(2)SeO(4) or Na(3)VO(4)) did inhibit alkylation. We propose that these oxo species behave as nucleophilic targets for the electrophilic alkylating agents, thereby preventing DNA damage.

Alkylation↗
PubMed2002

Metvan: a novel oxovanadium(IV) complex with broad spectrum anticancer activity.

Among the 25 bis(cyclopentadienyl)vanadium(IV) and 14 oxovanadium(IV) compounds synthesised and evaluated for anticancer activity, bis(4,7-dimethyl-1,10-phenanthroline) sulfatooxovanadium(IV) (metvan) was identified as the most promising multitargeted anticancer vanadium complex with apoptosis-inducing activity. At nanomolar and low micromolar concentrations, metvan induces apoptosis in human leukaemia cells, multiple myeloma cells and solid tumour cells derived from breast cancer, glioblastoma, ovarian, prostate and testicular cancer patients. It is highly effective against cisplatin-resistant ovarian cancer and testicular cancer cell lines. Metvan is much more effective than the standard chemotherapeutic agents dexamethasone and vincristine in inducing apoptosis in primary leukaemia cells from patients with acute lymphoblastic leukaemia, acute myeloid leukaemia or chronic acute myeloid leukaemia. Metvan-induced apoptosis is associated with a loss of mitochondrial transmembrane potential, the generation of reactive oxygen species and depletion of glutathione. Treatment of leukaemia cells from acute lymphoblastic leukaemia, acute myeloid leukaemia and chronic acute myeloid leukaemia patients with metvan inhibits the constitutive expression as well as the gelatinolytic activities of matrix metalloproteinase-9 and -2. Treatment of human malignant glioblastoma and breast cancer cells with metvan at concentrations > 1 microM is associated with a nearly complete loss of the adhesive, migratory and invasive properties of the treated cancer cell populations. Metvan shows favourable pharmacokinetics in mice and does not cause acute or subacute toxicity at the dose levels tested (12.5 - 50 mg/kg). Therapeutic plasma concentrations > or = 5 microM, which are highly cytotoxic against human cancer cells, can be rapidly achieved and maintained in mice for at least 24 h after intraperitoneal bolus injection of a single 10 mg/kg non-toxic dose of metvan. Metvan exhibits significant antitumour activity, delays tumour progression and prolongs survival time in severe combined immunodeficient mouse xenograft models of human malignant glioblastoma and breast cancer. The broad spectrum anticancer activity of metvan together with favourable pharmacodynamic features and lack of toxicity warrants further development of this oxovanadium compound as a new anticancer agent. Metvan could represent the first vanadium complex as an alternative to platinum-based chemotherapy.

Animals↗
PubMed1998

Spermicidal activity of metallocene complexes containing vanadium(IV) in humans.

We have used computer-assisted sperm analysis (CASA) to evaluate the spermicidal activity of 8 metallocene dihalides (vanadocene dichloride [VDC], titanocene dichloride [TDC], zirconocene dichloride [ZDC], molybdocene dichloride [MDC], hafnocene dichloride [HDC], vanadocene dibromide [VDB], bis[methylcyclopentadienyl] vanadium dichloride [VMDC], and vanadocene diiodide [VDI]); 5 vanadocene di-pseudohalides (vanadocene diazide [VDA], vanadocene dicyanide [VDCN], vanadocene dioxycyanate [VDOCN], vanadocene dithiocyanate [VDSCN], and vanadocene diselenocyanate [VDSeCN]); and 3 disubstituted derivatives (vanadocene ditriflate [VDT], vanadocene monochloro oxycyanate [VDCO], and vanadocene monochloro acetonitrilo tetrachloro ferrate [VDFe]). Whereas the metallocene complexes containing titanium, zirconium, molybdenum, and hafnodium were inactive, all 12 vanadocene complexes elicited potent spermicidal activity at nano-micromolar concentrations with an order of efficacy VDSeCN > VDSCN > VDB > VMDC > VDCN > VDA > VDC > VDOCN > VDI > VDT > VDFe > VDCO without disrupting the acrosomal membrane, as determined by high-resolution low-voltage scanning electron microscopy. The sperm-immobilizing activity of the vanadocene complexes was rapid and irreversible, since the treated sperm underwent apoptosis as determined by the flow cytometric annexin V binding assay, DNA nick end-labeling, and confocal laser scanning microscopy. These results provide unprecedented evidence that metallocene complexes containing vanadium(IV), especially VDSeCN, may be useful as contraceptive agents.

Deferoxamine↗
PubMed2005

New insights into the interactions of serum proteins with bis(maltolato)oxovanadium(IV): transport and biotransformation of insulin-enhancing vanadium pharmaceuticals.

Significant new insights into the interactions of the potent insulin-enhancing compound bis(maltolato)oxovanadium(IV) (BMOV) with the serum proteins, apo-transferrin and albumin, are presented. Identical reaction products are observed by electron paramagnetic resonance (EPR) with either BMOV or vanadyl sulfate (VOSO4) in solutions of human serum apo-transferrin. Further detailed study rules out the presence of a ternary ligand-vanadyl-transferrin complex proposed previously. By contrast, differences in reaction products are observed for the interactions of BMOV and VOSO4 with human serum albumin (HSA), wherein adduct formation between albumin and BMOV is detected. In BMOV-albumin solutions, vanadyl ions are bound in a unique manner not observed in comparable solutions of VOSO4 and albumin. Presentation of chelated vanadyl ions precludes binding at the numerous nonspecific sites and produces a unique EPR spectrum which is assigned to a BMOV-HSA adduct. The adduct species cannot be produced, however, from a solution of VOSO4 and HSA titrated with maltol. Addition of maltol to a VOSO4-HSA solution instead results in formation of a different end product which has been assigned as a ternary complex, VO(ma)(HSA). Furthermore, analysis of solution equilibria using a model system of BMOV with 1-methylimidazole (formation constant log K1 = 4.5(1), by difference electronic absorption spectroscopy) lends support to an adduct binding mode (VO(ma)2-HSA) proposed herein for BMOV and HSA. This detailed report of an in vitro reactivity difference between VOSO4 and BMOV may have bearing on the form of active vanadium metabolites delivered to target tissues. Albumin binding of vanadium chelates is seen to have a potentially dramatic effect on pharmacokinetics, transport, and efficacy of these antidiabetic chelates.

Apoproteins↗
PubMed2002

Fever and neutrophilic alveolitis caused by a vanadium based catalyst.

AIMS: To investigate a worker who experienced systemic and respiratory symptoms when exposed to a vanadium containing powder used as a catalyst in the production of maleic anhydride. METHODS: The investigation included inhalation challenge with the suspected compound combined with monitoring of lung function tests and post-challenge bronchoalveolar lavage. RESULTS: Exposure to the vanadium containing catalyst for 120 minutes resulted in a sustained decline in forced vital capacity and forced expiratory volume in one second, while the transfer factor for carbon monoxide did not change significantly. The subject developed fever and peripheral blood neutrophilia. Bronchoalveolar lavage performed 48 hours after the end of challenge exposure showed a marked increase in neutrophils (60% of total cell count). CONCLUSIONS: Exposure to vanadium can cause a metal fume fever-like syndrome associated with neutrophilic alveolitis.

Adult↗
PubMed2006

Alkylation of inorganic oxo compounds and insights on preventing DNA damage.

Metabolism of food- and tobacco-borne procarcinogens results in the exposure of DNA to toxic alkylating agents. These assaults can bring about DNA alkylation damage, mutations, and cancer. Dietary inorganic compounds such as selenium and vanadium are known to prevent cancer, possibly by reacting directly with alkylating agents, thereby preventing DNA damage. To understand potential interactions between oxo species and alkylating toxins, we reacted a series of alkylating agents with varied classes of oxo compounds (i.e., vanadates, selenate, phosphate, sulfate, acetate, nitrate, and nitrite). A new organic-soluble selenate, [(C6H5)4P]3(O3SeOCH2OSeO3)(HSeO4), was synthesized and characterized for these studies. Vanadates were found to convert ethylating agents into ethanol, whereas other anions formed esters upon alkylation. General trends show that oxo anions of the greatest charge density were the most reactive. These studies suggest that the design of new compounds for cancer prevention should incorporate reactive oxo groups with high anionic charge density.

Acetates↗
PubMed1996

Use of the Syrian hamster embryo cell transformation assay for determining the carcinogenic potential of heavy metal compounds.

Cobalt sulfate hydrate, gallium arsenide, molybdenum trioxide, vanadium pentoxide, and nickel sulfate heptahydrate were tested in the Syrian hamster embryo (SHE) assay in order to increase the SHE assay database for heavy metals. All five compounds produced significant morphological transformation at one or more doses in a dose-responsive manner. Cobalt sulfate hydrate, gallium arsenide, molybdenum trioxide, and nickel (II) sulfate heptahydrate were all positive with a 24-hr exposure, suggesting direct DNA perturbation. Vanadium pentoxide was negative with a 24-hr exposure, but positive with a 7-day exposure. This pattern of response (24-hr SHE negative/7-day SHE positive) has been seen with other chemicals which have tumor promotion-like characteristics. Since the inception of the use of the SHE cell transformation assay for detecting the neoplastic transformation potential of chemicals, over 42 heavy metal compounds have been tested in this assay. Based on the 24 metal compounds which have been tested in the SHE, Salmonella, and some type of rodent bioassay, the SHE assay is 92% concordant with rodent bioassay carcinogenicity results, including a sensitivity of 95% (21/22) and a specificity of 50% (1/2). At this time, the measure of SHE assay specificity for rodent carcinogenicity of metals is limited by the paucity of metal compounds which are rodent noncarcinogens. The Salmonella assay results are only 33% concordant with the rodent bioassay for these same chemicals. This relatively high concordance between the SHE assay and the rodent bioassay carcinogenicity results demonstrates the utility of the SHE assay for determining the carcinogenic potential of heavy metal compounds in rodent cancer bioassays.

Animals↗
PubMed2006

Structural characterization and oxidative dehydrogenation activity of V2O5/Ce(x)Zr(1-x)O2/SiO2 catalysts.

The thermal stability of a nanosized Ce(x)Zr(1-x)O2 solid solution on a silica surface and the dispersion behavior of V2O5 over Ce(x)Zr(1-x)O2/SiO2 have been investigated using XRD, Raman spectroscopy, XPS, HREM, and BET surface area techniques. Oxidative dehydrogenation of ethylbenzene to styrene was performed as a test reaction to assess the usefulness of the VOx/Ce(x)Zr(1-x)O2/SiO2 catalyst. Ce(x)Zr(1-x)O2/SiO2 (1:1:2 mol ratio based on oxides) was synthesized through a soft-chemical route from ultrahigh dilute solutions by adopting a deposition coprecipitation technique. A theoretical monolayer equivalent to 10 wt % V2O5 was impregnated over the calcined Ce(x)Zr(1-x)O2/SiO2 sample (773 K) by an aqueous wet impregnation technique. The prepared V2O5/Ce(x)Zr(1-x)O2/SiO2 sample was subjected to thermal treatments from 773 to 1073 K. The XRD measurements indicate the presence of cubic Ce0.75Zr0.25O2 in the case of Ce(x)Zr(1-x)O2/SiO2, while cubic Ce0.5Zr0.5O2 and tetragonal Ce0.16Zr0.84O2 in the case of V2O5/Ce(x)Zr(1-x)O2/SiO2 when calcined at various temperatures. Dispersed vanadium oxide induces more incorporation of zirconium into the ceria lattice, thereby decreasing its lattice size and also accelerating the crystallization of Ce-Zr-O solid solutions at higher calcination temperatures. Further, it interacts selectively with the ceria portion of the composite oxide to form CeVO4. The RS measurements provide good evidence about the dispersed form of vanadium oxide and the CeVO4 compound. The HREM studies show the presence of small Ce-Zr-oxide particles of approximately 5 nm size over the surface of amorphous silica and corroborate with the results obtained from other techniques. The catalytic activity studies reveal the ability of vanadium oxide supported on Ce(x)Zr(1-x)O2/SiO2 to efficiently catalyze the ODH of ethylbenzene at normal atmospheric pressure. The remarkable ability of Ce(x)Zr(1-x)O2 to prevent the deactivation of supported vanadium oxide leading to stable activity in the time-on-stream experiments and high selectivity to styrene are other important observations.

Journal Article↗
PubMed1996

COMPACT and molecular structure in toxicity assessment: a prospective evaluation of 30 chemicals currently being tested for rodent carcinogenicity by the NCI/NTP.

A new series of 30 miscellaneous National Toxicology Program chemicals has been evaluated prospectively for carcinogenicity and overt toxicity by COMPACT (Computer Optimised Molecular Parametric Analysis for Chemical Toxicity. CYP1A and CYP2E1). Evaluations were also made by Hazardexpert, and for metal ion redox potentials; and these, together with COMPACT, were compared with results from the Ames test for mutagenicity in Salmonella, the micronucleus test, and 90-day subchronic rodent pathology. Seven of the 30 chemicals (nitromethane, chloroprene, xylenesulphonic acid, furfuryl alcohol, anthraquinone, emodin, cinnamaldehyde) were positive for potential carcinogenicity in the COMPACT evaluation; xylenesulphonic acid and furfuryl alcohol were only equivocally positive. Four of the 30 chemicals-scopolamine, D&C Yellow No. 11, citral, cinnamaldehyde-were positive by Hazardexpert; 6 of 30-D&C Yellow No. 11, 1-chloro-2-propanol, anthraquinone, emodin, sodium nitrite, cinnamaldehyde-were positive in the Ames test; 2 of 30-phenolphthalein and emodin-were positive in the in vivo cytogenetics test; and 3 of 30-molybdenum trioxide, gallium arsenide, vanadium pentoxide-were metal compounds with redox potentials of the metal/metal ion indicative of possible carcinogenicity. The overall prediction for carcinogenicity was positive for 12 of 30 chemicals: nitromethane, chloroprene, D&C Yellow No. 11, molybdenum trioxide, 1-chloro-2-propanol, furfuryl alcohol, gallium arsenide, anthraquinone, emodin, sodium nitrite, cinnamaldehyde, vanadium pentoxide). This overall prediction has been made on the basis of the results of the computer tests and from consideration of the information from bacterial mutagenicity, together with likely lipid solubility and pathways of metabolism and elimination.

Animals↗
PubMed2000

Inhibitors of Na-K-ATPase in human urine: effects of ouabain-like factors and of vanadium-diascorbate on calcium mobilization in rat vascular smooth muscle cells: comparison with the effects of ouabain, angiotensin II, and arginine-vasopressin.

Endogenous ouabain-like factors (OLF) may play a role in the pathogenesis of volume-dependent hypertension by raising intracellular free calcium ([Ca2+]i) as a consequence of inhibition of the sodium pump. In previous studies we described the presence of two low molecular (Mr approximately equals 400) inhibitors of Na-K-ATPase in human urine, ie, a more polar OLF-1 and a more apolar OLF-2. We subsequently identified the active compound in OLF-2 as vanadium (V(IV))-diascorbate (Mr 416). OLF-1, OLF-2, and V-diascorbate inhibited dose-dependently porcine Na-K-ATPase in vitro. In the present study we investigated the effects of urinary OLF-1, OLF-2, and V-diascorbate on calcium mobilization, ie, on [Ca2+]i in cultured rat vascular smooth muscle (VSM) cells in comparison to the effects of ouabain, angiotensin II (A II), and arginine-vasopressin (AVP). [Ca2+]i was determined by the fura-2 method. OLF-1 and OLF-2 (each approximately equals 10(-4) mol/L), obtained as single spots by thin-layer chromatography, produced a rise in [Ca2+]i in VSM cells from 45 +/- 7 to 99 +/- 22 and from 48 +/- 9 to 92 +/- 2 nmol/L (each n = 5; P < .05), respectively, after 3 min. V-diascorbate also increased [Ca2+]i slowly and dose-dependently, eg, from 56 +/- 14 to 102 +/- 15 nmol/L at a concentration of 10(-6) mol/L (n = 5; P < .05) after 3 min. A similar slow rise in [Ca2+]i from 53 +/- 10 to 185 +/- 3 nM (n = 5; P < .05) after 3 min was found with ouabain (10(-6) mol/L). As standard vasoconstrictor, All (10(-8) mol/L) rapidly increased [Ca2+]i from 23 +/- 4 to 846 +/- 50 nmol/L (n = 7; P < .01) within 30 sec. This effect was enhanced to 1,389 +/- 161 nM (n = 7; P < .01) when VSM cells were preincubated with V-diascorbate (10(-6) mol/L) for 10 min. AVP (10(-7) mol/L) also rapidly increased [Ca2+]i to 418 +/-11 nmol/L within 30 sec (n = 7; P < .01). This effect was enhanced in the presence of OLF-2 (approximately equals 10(-4) mol/L) or ouabain (10(-6) mol/L) to 523 +/- 14 and 560 +/- 19 nmol/L, respectively (each n = 7); P < .01). The calcium channel blocker verapamil, the intracellular calcium release blocker TMB-8, and the unselective cation channel blocker Ni2+ partly blunted the A II- or AVP-induced rise in [Ca2+]i and prevented the OLF-2- and V-diascorbate-induced increase in [Ca2+]i. Thus, OLF-1, OLF-2 and V-diascorbate, the active component of OLF-2, reveal effects similar to those of ouabain on [Ca2+]i in VSM cells, ie, they produce a slow rise in [Ca2+]i subsequent to inhibition of the sodium pump. The physiologic and pathologic roles of these and additional OLF in body fluid and blood pressure regulation and in hypertension have yet to be evaluated.

Adult↗
PubMed2000

Synthesis and magnetic and transport properties of Sr6V9S22O2: "AM2S5" phases revisited.

The compound Sr6V9S22O2 was prepared from SrS, sulfur, vanadium metal, and V2O5 at 950 degrees C in an evacuated quartz tube. The compound is rhombohedral, R3, with a = 8.7538(6) A, c = 34.934(3) A, and Z = 3, and shows strong preferred orientation in its XRD profiles (00l) due to the layered nature of the structure. The compound contains charged CdI2 type VS2 layers of formula [V7S14]4- separated by [Sr6(VOS3)2(S2)]4+ layers. The latter has VOS3(3-) tetrahedra and S2(2-) disulfide units linked by Sr2+ ions. Magnetic susceptibility and four-probe resistivity studies show essentially temperature-independent paramagnetism above 80 K and small gap semiconductor behavior, respectively. The compound has a positive Hall coefficient at room temperature. The relationship among Sr6V9S22O2, "SrV2S5" (J. Solid State Chem. 1996, 126, 189), and other AM2S5 phases is discussed.

Journal Article↗
PubMed2005

Neutral and cationic V(IV)/V(V) mixed-valence alkoxo-polyoxovanadium clusters [V6O7(OR)12]n+ (R = -CH3, -C2H5): structural, cyclovoltammetric and IR-spectroscopic investigations on mixed valency in a hexanuclear core.

The alkoxo-polyoxovanadium clusters [V6O7(OR)12]n+ (R = -CH3, -C2H5) are fully alkylated polyoxometalate derivatives comprising a hexavanadate core with the vanadium ions organized in an octahedral fashion, a classic isopolyoxometalate structure (Lindqvist) which as an entity is not known for vanadium. The clusters are highly redox-active compounds, displaying a large number of thermodynamically stable redox isomers of which the chemical syntheses and structural characterization of the neutral and cationic V(IV)/V(V) mixed-valence species [V(IV)(4-n)V(V)(2+n)O7(OR)12]n+ [SbCl6]n (R = -CH3, n = 0, 1; R = -C2H5, n = 0, 1, 2) are presented here. Neutral and positively charged clusters remain exceptional in the field of polyoxometalate chemistry. Results obtained from cyclic voltammetry, infrared spectroscopy, and from valence sum calculations conducted on X-ray structural data classify these clusters as class II mixed-valence compounds. Their highly symmetrical molecular structures make them particularly interesting as model compounds for the investigation of intervalence charge transfer and electron delocalization in the hexanuclear core. Furthermore, the large number of isostructural redox isomers affords a high variability in d-electron content. Accordingly, a dependency could clearly be established between the extent of electron delocalization and the V(IV)/V(V) ratio in a cluster species. A further interesting observation concerns the neutral ethoxo compound [V(IV)4V(V)2O7(OC2H5)12] (3) which exhibits a crystallographic phase transition accompanied by the conversion from a structure at 173 K with fully localized valencies to a room-temperature modification displaying complete d-electron delocalization.

Cations↗
PubMed1996

Synthesis and Characterization of Hydrotalcite-like Compounds Containing V(3+) in the Layers and of Their Calcination Products.

The synthesis and full characterization of a new hydrotalcite-like compound with the formula [Mg(0.71)V(0.29)(OH)(2)](CO(3))(0.145).0.72H(2)O and with V(3+) in the layers are described. The influence of hydrothermal treatment and drying rate on the crystallinity of the materials obtained is discussed. The evolution to mixed oxides upon calcination at different temperatures (448, 548, 773, 1023, and 1273 K) under different atmosphere environments (air or nitrogen) for 2 h has been studied. Characterization of the original layered materials and of the calcination products has been carried out by X-ray diffraction, thermal analysis, Fourier-transform infrared spectroscopy, BET specific surface area determination, temperature-programmed reduction, and transmission electron microscopy. X-ray absorption spectroscopies (XANES and EXAFS) have also been used to assess the local geometry of vanadium ions in the different compounds prepared. All experimental data agree with a well-crystallized hydrotalcite-like compound after thermal treatment, and also a minor effect of the drying rate on the crystallinity has been found. Thermal decomposition yields poorly crystalline layered compound at 448 K that undergoes transformation to mostly amorphous materials when calcined at 548-773 K, finally leading to a mixture of MgO and Mg(3)V(2)O(8), which has increasing crystallinity as the calcination temperature increases. XAS results indicate the presence of V(3+) ions in an octahedral coordination in the parent sample calcined at 448 K and tetrahedrally coordinated V(5+) species for samples calcined at higher temperatures, calcination giving rise to a better ordering of the second coordination sphere. Similar results were found when calcination was performed in nitrogen, although higher temperatures were needed to achieve the same result.

Journal Article↗
PubMed2005

Racemic monoperoxovanadium(V) complexes with achiral OO and ON donor set heteroligands: synthesis, crystal structure and stereochemistry of [NH3(CH2)2NH3][VO(O2)(ox)(pic)].2H2O and [NH3(CH2)2NH3][VO(O2)(ox)(pca)].

Monoperoxovanadium(V) complexes, [NH3(CH2)2NH3][VO(O2)(ox)(pic)].2H2O (1) and [NH3(CH2)2NH3][VO(O2)(ox)(pca)] (2) [NH3(CH2)2NH3 = ethane-1,2-diammonium(2+), ox=oxalate(2-), pic=pyridine-2-carboxylate(1-), pca=pyrazine-2-carboxylate(1-)], were synthesized and characterized by X-ray analysis, IR and Raman spectroscopies. The five equatorial positions of the pentagonal bipyramid around the vanadium atoms are occupied by the eta2-peroxo ligand, two oxygen atoms of the ox, and the nitrogen atom of the pic or pca ligands, respectively. The oxo ligand and the oxygen atom of pic or pca are in the axial positions. Networks of X-HO (X=C, N or O) hydrogen bonds, and pi-pi interactions between aromatic rings in and anion-pi interactions in , determine the molecular packings and build up the supramolecular architecture. Three stereochemical rules for occupation of the donor sites in two-heteroligand [VO(O2)(L1)(L2)] complexes (L1, L2 are bidentate neutral or differently charged anionic heteroligands providing an OO, NN or ON donor set) are discussed. and crystallize as racemic compounds. The 51V NMR spectra proved that the parent complex anions of and partially decompose on dissolution in water to the monoperoxo-ox, -pic or -pca complexes.

Ammonia↗
PubMed2000

Apoptosis-inducing vanadocene compounds against human testicular cancer.

We systematically assessed the cytotoxic effects of five metallocene dichlorides containing vanadium (vanadocene dichloride), titanium (titanocene dichloride), zirconium (zircodocene dichloride), molybdenum (molybdocene dichloride), and hafnium (hafnocene dichloride) as the central metal atom and 19 other vanadocene complexes. These compounds were tested against the human testicular cancer cell lines Tera-2 and Ntera-2 using both 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays and apoptosis assays. Notably, only the vanadium(IV)-containing metallocenes exhibited significant cytotoxicity against Tera-2 and Ntera-2 cells and induced apoptosis within 24 h. Vanadocenes with dithiocyanate [VCp2(SCN)2 x 0.5 H2O] and diselenocyanate [VCp2(NCSe)2] as ancillary ligands were identified as the most potent cytotoxic compounds. Vanadocenes, especially the lead compound VCp2(NCSe)2, may be useful in the treatment of testicular cancer.

Apoptosis↗
PubMed2004

Effect of macrocyclic binuclear oxovanadium complex on tissue defense system in streptozotocin-induced diabetic rats.

BACKGROUND: Oxidative stress plays an important role in chronic complications of diabetes mellitus and hence the regulation of free radicals is essential in the treatment of diabetes. The protective effect of a new macrocyclic binuclear oxovanadium complex on antioxidant defense systems of liver and kidney was examined in streptozotocin-induced experimental diabetes in rats. METHODS: The levels of lipid peroxides, glutathione and the activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase were assayed according to standard procedures in the liver and kidney of control and experimental groups of rats. RESULTS: A significant decrease (p < 0.05) was observed in both the glutathione content and in the activities of antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase and a concomitant increase in the level of lipid peroxides in diabetic rats. The observed alterations in the antioxidant status of tissues reverted back to near normal levels after the oral administration of macrocyclic vanadium complex at a dose of 5 mg/kg body weight/rat/day for a period of 30 days. CONCLUSION: The normoglycemic efficacy of the vanadium complex alleviates oxidative stress in streptozotocin-induced diabetes in rats.

Animals↗
PubMed1990

Developmental toxicity of vanadium in mice after oral administration.

Vanadium, as vanadyl sulphate pentahydrate, was evaluated for its embryotoxic, fetotoxic and teratogenic potential in Swiss mice. The compound was administered by gavage to pregnant mice at doses of 0, 37.5, 75 or 150 mg kg-1 day-1 on days 6-15 of pregnancy. On gestation day 18, all live fetuses were examined for external, visceral and skeletal malformations and variations. Maternal toxicity was observed in the vanadium-treated animals, as evidenced by reduced weight gain, reduced body weight on gestation day 18 (corrected for gravid uterine weight) and decreased absolute liver and kidney weights at 75 and 150 mg kg-1 day-1. The number of total implants, live and dead fetuses, late resorptions, the sex ratio and the post-implantation losses were not significantly different between the vanadium-treated mice and the controls. However, there was a significant increase in the number of early resorptions per litter at all dose levels. Fetotoxicity was evidenced by lower fetal weights and fetal lengths, and the presence of developmental variations. Malformation incidence also was increased by the administration of vanadium. Thus, the 'no observable effect level' (NOEL) for maternal toxicity, embryofetotoxicity and teratogenicity for vanadyl sulphate pentahydrate under these test conditions was below 37.5 mg kg-1 day-1 for Swiss mice.

Abnormalities, Drug-Induced↗