Photocatalytic Degradation of Palm Oil Mill Effluent (POME) Waste Using BiVO4 Based Catalysts.

Disposal of palm oil mill effluent (POME), which is highly polluting from the palm oil industry, needs to be handled properly to minimize the harmful impact on the surrounding environment. Photocatalytic technology is one of the advanced technologies that can be developed due to its low operating costs, as well as being sustainable, renewable, and environmentally friendly. This paper reports on the photocatalytic degradation of palm oil mill effluent (POME) using a BiVO4 photocatalyst under UV-visible light irradiation. BiVO4 photocatalysts were synthesized via sol-gel method and their physical and chemical properties were characterized using several characterization tools including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), surface area analysis using the BET method, Raman spectroscopy, electron paramagnetic resonance (EPR), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The effect of calcination temperature on the properties and photocatalytic performance for POME degradation using BiVO4 photocatalyst was also studied. XRD characterization data show a phase transformation of BiVO4 from tetragonal to monoclinic phase at a temperature of 450 °C (BV-450). The defect site comprising of vanadium vacancy (Vv) was generated through calcination under air and maxima at the BV-450 sample and proposed as the origin of the highest reaction rate constant (k) of photocatalytic POME removal among various calcination temperature treatments with a k value of 1.04 × 10-3 min-1. These findings provide design guidelines to develop efficient BiVO4-based photocatalyst through defect engineering for potential scalable photocatalytic organic pollutant degradation.

Deep eutectic solvent synthesis of iron vanadate-decorated sulfur-doped carbon nanofiber nanocomposite: electrochemical sensing tool for doxorubicin.

Detection of anticancer drug (doxorubicin) using an electrochemical sensor is developed based on a transition metal vanadate's related carbon composite material. With an environmentally friendly process, we have synthesized a metal oxide composite of iron vanadate nanoparticle assembled with sulfur-doped carbon nanofiber (FeV/SCNF). The FeV/SCNF composite was characterized using XRD, TEM, FESEM with elemental mapping, XPS and EDS. In contrast to other electrodes reported in the literature, a much-improved electrochemical efficiency is shown by FeV/SCNF composite modified electrodes. Amperometric technique has been employed at 0.25 V (vs. Ag/AgCl) for the sensitive detection of DOX within a wide range of 20 nM-542.5 µM and it possesses enhanced selectivity in presence of common interferents. The modified electrochemical sensors show high sensitivity of 46.041 µA µM-1 cm-2. The newly developed sensor could be used for the determination of doxorubicin in both blood serum and drug formulations with acceptable results, suggesting its feasibility for real-time applications.

New Insights into The Photoactivity of Shape-Tailored BiVO4 Semiconductors via Photocatalytic Degradation Reactions and Classical Reduction Processes.

In the present study, additive-free, pH-driven, hydrothermal crystallization was used to obtain shape-tailored monoclinic BiVO4 photocatalysts. The as-prepared BiVO4 products were systematically characterized, uncovering their crystallographic, morphologic and optical properties, while their applicability was verified in the visible light-driven photodegradation of oxalic acid and rhodamine B. Monoclinic clinobisvanite was obtained in most cases, with their band gap values located between 2.1 and 2.4 eV. The morphology varied from large, aggregated crystals, individual microcrystals to hierarchical microstructures. It was found that the degradation efficiency values obtained in the case of oxalic acid were directly related to the presence of (040) crystallographic plane, while the degradation of rhodamine B was partially independent by the presence of this structural feature. The importance of (040) crystallographic plane was also demonstrated via the reduction of Cu2+ to Cu, by analyzing the Raman spectra of the Cu containing samples, the mean primary crystallite size of Cu and Cu content. Furthermore, the presence of (040) crystallographic plane was directly proportional with the hydrodynamic properties of the powders as well.

Solvothermal synthesis of facet-dependent BiVO4 photocatalyst with enhanced visible-light-driven photocatalytic degradation of organic pollutant: assessment of toxicity by zebrafish embryo.

The BiVO4 photocatalyst plays a very important role in photocatalytic reactions attributed to its unique crystalline structure, size, morphology and surface area. Herein, we report a facet-dependent monoclinic scheelite BiVO4 (m-BiVO4) photocatalyst with uniform truncated square (18 sided) hexagonal bipyramidal shape synthesized by a template-free and surfactant-free solvothermal method using ethylene glycol solvent under cost-effective and mild reactions. The structural, morphological and optical properties of the m-BiVO4 photocatalyst are widely characterized. The photocatalytic activity of the m-BiVO4 photocatalyst is tested towards 20 ppm methylene blue (MB) dye aqueous solution as a pollutant model under visible light irradiation. Enhanced visible-light driven photoactivity with dye degradation efficiency of approx. 91% at a rate of 0.388 × 10-2 min-1 is obtained, presumably due to the presence of high-active (040) facets. Zebrafish embryo toxicity test of treated MB dye solution reveals the degradation and toxicity reduction of the MB dye. Moreover, the recycling experiment validates that the m-BiVO4 photocatalyst has a great structural stability with reliable performance. This work may provide a lucid and expedient strategy to synthesize highly crystalline (040) facet-dependent semiconductor photocatalyst toward dye degradation and obviously industrial wastewater remediation.

Cyclo-tetravanadate bridged copper complexes as potential double bullet pro-metallodrugs for cancer treatment.

Over the last decade, copper and vanadium complexes have shown promising properties for the treatment of several types of cancer. In particular, Casiopeinas®, a group of copper-based complexes, has received specific attention, and their mechanism of action has been extensively studied since their structure is simple and their synthesis may be affordable. Similarly, vanadium-containing compounds in the form of complexes and simple polyoxovanadates have also been studied as antitumor agents. Here, potential prodrugs that would release the two metals, V and Cu, in usable form to act in conjunction against cancer cells are reported. The new series of Casiopeinas-like compounds are bridged by a cyclotetravanadate ion with the generic formula [Cu(N,N')(AA)]2•(V4O12), where (N,N') represent 1,10-phenanthroline and 2,2'-bipyridine, and (AA) are aminoacidate ions (Lysine and Ornithine). The compounds were characterized by elemental analysis, single-crystal X-ray diffraction and Visible, FTIR, and Raman spectroscopies, as well as 51V NMR, EPR, and Thermogravimetric Analysis. Additionally, theoretical calculations based on the Density Functional Theory (DFT) were carried out to model the compounds. Optimized structures, theoretical IR, and Raman spectra were also obtained, as well as docking analysis to test DNA interactions with the casiopeina-like complexes. The compounds may act as prodrugs by providing acting molecules that have showed potential pharmacological properties for the treatment of several types of cancer.

Influence of AgVO3 incorporation on antimicrobial properties, hardness, roughness and adhesion of a soft denture liner.

The objective of this in vitro study was to investigate the effect of nanostructured silver vanadate decorated with silver nanoparticles (AgVO3) on antimicrobial activity, hardness, roughness, and adhesion of a soft denture liner. The antimicrobial efficacy of the Trusoft (Boswoth) liner incorporated with different concentrations of AgVO3 against Enterococcus faecalis, Pseudomonas aeruginosa, Candida albicans, and Staphyloccocus aureus (n = 5) was evaluated by the agar diffusion method. Roughness, hardness, and adhesion properties were also evaluated. The data were analyzed by analysis of variance (ANOVA) and Tukey's multiple comparison test with significance at the p < 0.05 level. At concentrations of 1 and 2.5%, AgVO3 incorporation was effective only against E. faecalis, and at 5 and 10%, against E. faecalis, P. aeruginosa, and C. albicans. None of the concentrations was effective against S. aureus. A decrease in hardness was found for the 1, 2.5, and 10% AgVO3 concentrations (p < 0.001) and at 5%, hardness was not affected. None of the concentrations affected the roughness of the material. A significant increase in tensile values was observed between the liner and heat-curing acrylic resin for 2.5% (p < 0.001) and 10% (p = 0.042) concentrations. AgVO3 incorporation to a soft denture liner promoted antimicrobial activity against E. faecalis, P. aeruginosa, and C. albicans without affecting roughness, maintaining the hardness properties recommended for soft and extra soft liners, and improving the adhesion between the liner and the acrylic resin used for dentures.

Visible-Light-Driven Single-Component BiVO4 Micromotors with the Autonomous Ability for Capturing Microorganisms.

Light-driven micro/nanomotors represent the next generation of automotive devices that can be easily actuated and controlled by using an external light source. As the field evolves, there is a need for developing more sophisticated micromachines that can fulfill diverse tasks in complex environments. Herein, we introduce single-component BiVO4 micromotors with well-defined micro/nanostructures that can swim both individually and as collectively assembled entities under visible-light irradiation. These devices can perform cargo loading and transport of passive particles as well as living microorganisms without any surface functionalization. Interestingly, after photoactivation, the BiVO4 micromotors exhibited an ability to seek and adhere to yeast cell walls, with the possibility to control their attachment/release by switching the light on/off, respectively. Taking advantage of the selective motor/fungal cells attachment, the fungicidal activity of BiVO4 micromotors under visible illumination was also demonstrated. The presented star-shaped BiVO4 micromotors, obtained by a hydrothermal synthesis, contribute to the potential large-scale fabrication of light-powered micromotors. Moreover, these multifunctional single-component micromachines with controlled self-propulsion, collective behavior, cargo transportation, and photocatalytic activity capabilities hold promising applications in sensing, biohybrids assembly, cargo delivery, and microbiological water pollution remediation.

Inhibition of Na+/K+- and Ca2+-ATPase activities by phosphotetradecavanadate.

Polyoxometalates (POMs) are promising inorganic inhibitors for P-type ATPases. The experimental models used to study the effects of POMs on these ATPases are usually in vitro models using vesicles from several membrane sources. Very recently, some polyoxotungstates, such as the Dawson anion [P2W18O62]6-, were shown to be potent P-type ATPase inhibitors; being active in vitro as well as in ex-vivo. In the present study we broaden the spectrum of highly active inhibitors of Na+/K+-ATPase from basal membrane of epithelial skin to the bi-capped Keggin-type anion phosphotetradecavanadate Cs5.6H3.4PV14O42 (PV14) and we confront the data with activity of other commonly encountered polyoxovanadates, decavanadate (V10) and monovanadate (V1). The X-ray crystal structure of PV14 was solved and contains two trans-bicapped α-Keggin anions HxPV14O42(9-x)-. The anion is built up from the classical Keggin structure [(PO4)@(V12O36)] capped by two [VO] units. PV14 (10 µM) exhibited higher ex-vivo inhibitory effect on Na+/K+-ATPase (78%) than was observed at the same concentrations of V10 (66%) or V1 (33%). Moreover, PV14 is also a potent in vitro inhibitor of the Ca2+-ATPase activity (IC50 5 µM) exhibiting stronger inhibition than the previously reported activities for V10 (15 µM) and V1 (80 µM). Putting it all together, when compared both P-typye ATPases it is suggested that PV14 exibited a high potential to act as an in vivo inhibitor of the Na+/K+-ATPase associated with chloride secretion.

Preparation of Ag-AgVO3/g-C3N4 composite photo-catalyst and degradation characteristics of antibiotics.

The degradation of tetracycline by silver vanadate (AgVO3), graphite-like carbon nitride (g-C3N4) and their composites was studied by visible light photocatalysis. Their structures and morphologies were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Their degradation intermediates were analyzed by GC-MS. Nanorod silver vanadate was synthesized by hydrothermal method. The results show that the gap between nanorods is reduced by adding spinning carbon nitride, and the photocatalytic performance of the composite is stronger than that of single material. The reaction rate constants of Ag-AgVO3/g-C3N4 composites were 0.0298 min-1, 2.4 and 2.0 times that of g-C3N4 (K=0.0125 min-1) and AgVO3 (K=0.0152 min-1), respectively. At 120 minutes, the degradation rate of the composites reached 83.6%. The degradation of tetracycline was confirmed by GC-MS, and a possible degradation process was proposed.

A new scheme for rational design and synthesis of polyoxovanadate hybrids with high antitumor activities.

A new strategy to construct polyoxovanadate hybrids incorporating amino acid esters in mild conditions was presented in this paper. These new hybrids were not only structurally determined by Single Crystal X-Ray diffraction, but also exhibited higher antitumor activities against laryngeal carcinoma, rhabdomyoma, and breast adenocarcinoma tumor cells compared with the traditional commercial medicine 5-fluorouracil. These results would provide a promising lead scaffold for further design and synthesis of potential anticancer agents.

Hierarchical biomimetic BiVO4 for the treatment of pharmaceutical wastewater in visible-light photocatalytic ozonation.

Photocatalytic ozonation is an attractive advanced oxidation process for wastewater treatment, but highly active catalysts with strong response to visible light are urgently needed to push forward its practical application. In this study, a hierarchical biomimetic monoclinic bismuth vanadate (BiVO4) with leaves morphology was synthesized by a hydrothermal method, and employed as catalyst for oxalic acid and penicillin degradation in photocatalytic ozonation. The results show that the organics degradation was more efficient using leaves shaped BiVO4 as catalyst than the bulk shaped one in photocatalytic ozonation and the synergy index is ranged from 2.8 to 3.3, indicating a superior positive synergistic effect between photocatalysis and ozonation. The higher activity of the leaves shaped BiVO4 was probably attributed to the distinctive biomimetic morphology and preferable band structure with more negative CB potential. Mechanism studies suggested that the main reactive species were h+ and OH for the degradation of persistent oxalic acid in photocatalytic ozonation. In addition, the effect of ozone concentration and inorganic ions and reusability of the material were also intensively investigated.

VAOS, a novel vanadyl complexes of alginate saccharides, inducing apoptosis via activation of AKT-dependent ROS production in NSCLC.

Previous studies have confirmed that protein tyrosine phosphatase 1B (PTP1B) can promote tumour progression in non-small cell lung cancer (NSCLC). Vanadyl alginate oligosaccharides (VAOS) is a new coordination compounds that possesses a good PTP1B inhibitory activity. However, the potent anticancer efficacy of VAOS in human NSCLC requires further study. In this study, VAOS exhibited effective inhibitory effects in NSCLC both in cultured cells and in a xenograft mouse model. VAOS was further identified to induce NSCLC cell apoptosis through activating protein kinase B (AKT) to elevate intracellular reactive oxygen species (ROS) levels by increasing in oxygen consumption and impairing the ROS-scavenging system. Neither silencing of PTP1B by siRNA nor transient overexpression of PTP1B had an effect on the AKT phosphorylation triggered by VAOS, indicating that PTP1B inhibition was not involved in VAOS-induced apoptosis. Through phosphorus colorimetric assay, we demonstrated that VAOS notably inhibited phosphatase and tensin homologue deleted on chromosome 10 (PTEN) dephosphorylation activity, another member of the protein tyrosine phosphatases (PTPases)-upstream factor of AKT. Interestingly, PTEN knockdown sensitized cells to VAOS, whereas ectopic expression of PTEN markedly rescued VAOS-mediated lethality. In vivo, VAOS treatment markedly reduced PTEN activity and tumour cell burden with low systemic toxicity. Thus, our data not only provided a new therapeutic drug candidate for NSCLC, but presented new understanding into the pharmacological research of VAOS.

Terpyridyl oxovanadium(IV) complexes for DNA crosslinking and mito-targeted photocytotoxicity.

Oxovanadium(IV) complexes [VO(L1/L2)Cl2]n+ (1,2) of (anthracenyl)terpyridine (An-tpy as L1 in 1, n=0) and triphenylphosphonium-appended (anthracenyl)terpyridine (An-tpy-TPP+ as L2 in 2, n=1) were synthesized, characterized and their DNA crosslinking ability, photocytotoxicity in visible light and cellular localization in cancer cells studied. The bromide derivative of 2, viz. [VO(An-tpy-TPP)Br2]Br (3) is structurally characterized. The structure showed trans disposition of two halides in the coordination sphere and the TPP+ unit is a pendant to the terpyridyl ligand. The DNA melting and comet assay studies on the complexes suggest the formation of DNA crosslinks. Complexes 1 and 2 displayed ~10 fold increase in cytotoxicity on exposure to visible light (400-700nm) when compared to those in dark in HeLa and MCF-7 cells. FACScan (Fluorescence Associated Cell Sorter Scan) analysis showed cellular apoptosis when treated with the complex in visible light in comparison to their dark controls. Fluorescence microscopic studies using complex 2 revealed its mitochondrial localization within the cancer cells.

Green synthesis of a novel flower-like cerium vanadate microstructure for electrochemical detection of tryptophan in food and biological samples.

In this present investigation, we introduced a novel electrochemical sensor for the detection of tryptophan (TRP) based on green pompoms flower-like cerium vanadate (CeVO4). The flower-like CeVO4 microstructure was prepared by the simple hydrothermal treatment with the assistance of urea for the first time. The as-prepared flower-like CeVO4 microstructure was characterized by various analytical and spectroscopic techniques such as X-ray diffraction, Raman spectroscopy fourier transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy studies. The electrochemical properties are evaluated by the cyclic voltammetry (CV) and differential pulse voltammetry (DPV). As an electrochemical sensor, the green pompoms flower-like CeVO4 modified glassy carbon electrode (GCE) displayed an excellent electrocatalytic activity for the detection of TRP. The obtained electrochemical results revealed that the oxidation of TRP, exhibited a lower potential and higher anodic peak current when compared to unmodified GCE. These results were suggested that the flower-like CeVO4/GCE have a good electrocatalytic activity towards the TRP oxidation. The flower-like CeVO4 sensor exhibited the wide linear concentration range and low detection limit of 0.1-94µM and 0.024µM respectively. Finally, the proposed sensor was successfully applied to the determination of TRP in real sample analysis such as food and biological samples with satisfied recoveries.

Synthesis and optical properties of Eu3+ -substituted glaserite-type orthovanadates CsK2 Y[VO4 ]2.

A new Eu3+ -substituted CsK2 Y[VO4 ]2 glaserite-type orthovanadate phosphor was synthesized by the conventional high temperature solid-state reaction method. The phase purity was confirmed by powder X-ray diffraction study and it reveals that all the compositions crystallize in the hexagonal structure. The morphology and elemental composition were measured by FE-SEM with Energy Dispersive Analysis Of X Rays (EDAX). The band gap is determined by diffuse reflectance spectra. The self-activated luminescence of the host and Eu3+ -substituted luminescence behaviours were studied in detail by photoluminescence spectra. The host CsK2 Y[VO4 ]2 shows green emission, whereas the Eu3+ -substituted compositions show red emission. Effect of Eu3+ concentrations on the photoluminescence behaviour were also been studied. The Eu3+ -doped samples show not only several sharp emission lines but also a broad emission band due to presence of the [VO4 ]3- in the host, which clearly indicates that there is incomplete energy transfer from (VO4 ) charge transfer band to Eu3+. The life time of the phosphors also been studied. The Commission Internationale de l'Eclairage (CIE) chromaticity colour coordinates were calculated and it is very much closer to the National Television Standard Committee (NTSC) standards. These investigations evidently reveal that the self-activated and Eu3+ -activated phosphors show a great potential applications as a red phosphor for solid-state lighting includes white light-emitting diodes (wLEDs).

Evaluation of cellular uptake, cytotoxicity and cellular ultrastructural effects of heteroleptic oxidovanadium(IV) complexes of salicylaldimines and polypyridyl ligands.

Searching for prospective vanadium-based drugs for cancer treatment, a new series of structurally related [VIVO(L-2H)(NN)] compounds (1-8) was developed. They include a double deprotonated salicylaldimine Schiff base ligand (L-2H) and different NN-polypyridyl co-ligands having DNA intercalating capacity. Compounds were characterized in solid state and in solution. EPR spectroscopy suggests that the NN ligands act as bidentate and bind through both nitrogen donor atoms in an axial-equatorial mode. The cytotoxicity was evaluated in human tumoral cells (ovarian A2780, breast MCF7, prostate PC3). The cytotoxic activity was dependent on type of cell and incubation time. At 24h PC3 cells presented low sensitivity, but at 72h all complexes showed high cytotoxic activity in all cells. Human kidney HEK293 and ovarian cisplatin resistant A2780cisR cells were also included to evaluate selectivity towards cancer cells and potency to overcome cisplatin resistance, respectively. Most complexes showed no detectable interaction with plasmid DNA, except 2 and 7 which depicted low ability to induce single strand breaks in supercoiled DNA. Based on the overall cytotoxic profile, complexes with 2,2´-bipyridine and 1,10-phenanthroline ligands (1 and 2) were selected for further studies, which consisted on cellular distribution and ultrastructural analyses. In the A2780 cells both depicted different distribution profiles; the former accumulates mostly at the membrane and the latter in the cytoskeleton. Morphology of treated cells showed nuclear atypia and membrane alterations, more severe for 1. Complexes induce different cell death pathways, predominantly necrosis for 1 and apoptosis for 2. Complexes alternative mode of cell death motivates the possibility for further developments.

Antioxidant and anticancer effects and bioavailability studies of the flavonoid baicalin and its oxidovanadium(IV) complex.

Based on the known antioxidant effect of flavonoids, baicalin (baic) found in roots of Scutellaria has been selected. Its coordination complex with the oxidovanadium(IV) cation, Na4[VO(baic)2].6H2O (VIVO(baic)), was synthesized at pH9 in ethanol and characterized by physicochemical methods. Spectrophotometric studies at pH9 showed a ligand: metal stoichiometry of 2:1. By vibrational spectroscopy a coordination mode through the cis 5-OH and 6-OH deprotonated groups is inferred. EPR spectroscopy shows an environment of four aryloxide (ArO-) groups in the equatorial plane of the VO moiety, both in solution and in the solid complex. The antioxidant capacity against superoxide and peroxyl radicals of VIVO(baic) resulted greater than for baicalin and correlated with previous results obtained for other VOflavonoid complexes. The coordination mode produces delocalization of the electron density and the stabilization of the radical formed by interaction with external radicals. The complex and the ligand displayed no toxic (Artemia salina test) and no mutagenic (Ames test) effects. The complex improved the ability of the ligand to reduce cell viability of human lung cancer cell lines (A549) generating reactive oxygen species (ROS) in cells, being this effect reversed by pre-incubation of the cells with antioxidants such as vitamins C and E. The addition of NAC (N-acetyl-l-cysteine, a sequestering agent of free radicals) suppresses the anticancer effect, confirming the oxidative stress mechanism. The complex interacted with bovine serum albumin (BSA) with stronger binding than baicalin and the mechanisms involved H bonding and van der Waals interactions.

Visible light induced bactericidal and photocatalytic activity of hydrothermally synthesized BiVO4 nano-octahedrals.

In the present work, monoclinic bismuth vanadate (m-BiVO4) nanostructures have been synthesized via simple hydrothermal method and employed for visible light driven antimicrobial and photocatalytic activity. Morphology (octahedral) and size (200-300nm) of the m-BiVO4 are studied using transmission electron microscopy (TEM). The crystal structure of m-BiVO4 (monoclinic scheelite structure) is confirmed by high resolution-TEM (HRTEM) and X-ray diffraction (XRD) studies. The band gap of m-BiVO4 was estimated to be ca. 2.42eV through Kubelka-Munk function F(R∞) using diffuse reflectance spectroscopy (DRS). Antimicrobial action of m-BiVO4 is anticipated by (i) shake flask method, (ii) MTT [3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide] assay for cytotoxicity. SEM analysis has been carried on Escherichia coli (E.coli) before and after treatment with nanostructure materials to reveal the mechanism underlying the antimicrobial action. Antimicrobial activity is studied as a function of m-BiVO4 concentration viz. 20, 40, 60 and 80ppm. The bacterial growth is decreased 80% to 96%, with the increase in m-BiVO4 concentration from 20ppm to 80ppm, respectively, in 2h. Photocatalytic activity and rate kinetics of m-BiVO4 nanostructures have been studied as a function of time on methylene blue (MB) dye degradation which is one of the waste products of textile industries and responsible for water pollution.

Behavior of the potential antitumor V(IV)O complexes formed by flavonoid ligands. 3. Antioxidant properties and radical production capability.

The radical production capability and the antioxidant properties of some V(IV)O complexes formed by flavonoid ligands were examined. In particular, the bis-chelated species of quercetin (que), [VO(que)2](2-), and morin (mor), [VO(mor)2], were evaluated for their capability to reduce the stable radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) and produce the hydroxyl radical (•)OH by Fenton-like reactions, where the reducing agent is V(IV)O(2+). The results were compared with those displayed by other V(IV)O complexes, such as [VO(H2O)5](2+), [VO(acac)2] (acac=acetylacetonate) and [VO(cat)2](2-) (cat=catecholate). The capability of the V(IV)O flavonoids complexes to reduce DPPH is much larger than that of the V(IV)O species formed by non-antioxidant ligands and it is due mainly to the flavonoid molecule. Through the 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin trapping assay of the hydroxyl radical it was possible to demonstrate that in acidic solution V(IV)O(2+) has an effectiveness in producing (•)OH radicals comparable to that of Fe(2+). When V(IV)O complexes of flavonoids were taken into account, the amount of hydroxyl radicals produced in Fenton-like reactions depends on the specific structure of the ligand and on their capability to reduce H2O2 to give (•)OH. Both the formation of reactive oxygen species (ROS) under physiological conditions by V(IV)O complexes of flavonoid ligands and their radical scavenging capability can be put in relationship with their antitumor effectiveness and it could be possible to modulate these actions by changing the features of the flavonoid coordinated to the V(IV)O(2+) ion, such as the entity, nature and position of the substituents and the number of phenolic groups.

A combined crystallographic analysis and ab initio calculations to interpret the reactivity of functionalized hexavanadates and their inhibitor potency toward Na(+)/K(+)-ATPase.

In vitro influence of five synthesized functionalized hexavanadates (V6) on commercial porcine cerebral cortex Na(+)/K(+)-ATPase activity has been studied. Dose dependent Na(+)/K(+)-ATPase inhibition was obtained for all investigated compounds. Calculated half maximal inhibitory concentration IC50 values, in mol/L, for Na(+)/K(+)-ATPase were 7.6×10(-5), 1.8×10(-5), 2.9×10(-5), 5.5×10(-5) for functionalized hexavanadates (V6) with tetrabutylammonium (TBA) [V6-CH3][TBA]2, [V6-NO2][TBA]2, [V6-OH][TBA]2 and [V6-C3][TBA]2 respectively. [V6-OH][Na]2 inhibited Na(+)/K(+)-ATPase activity up to 30% at maximal investigated concentration 1×10(-3)mol/L. This reactivity has been interpreted using a study of the non-covalent interactions of functionalized hexavanadate hybrids through Cambridge Structural Database (CSD) analysis. Bibliographic searching has led to 18 different structures and 99 contacts. We have observed that C-H⋯O contacts consolidate the structures. We have also performed density functional theory (DFT) calculations and have determined electrostatic potential values at the molecular surface on a series of functionalized V6. These results enlightened their chemical reactivity and their potential biological applications such as the inhibition of the ATPase.