Promotion effect of Ce and Ta co-doping on the NH3-SCR performance over V2O5/TiO2 catalyst.

NH3-SCR (SCR: Selective catalytic reduction) is an effective technology for the de-NOx process from both mobile and stationary pollution sources, and the most commonly used catalysts are the vanadia-based catalysts. An innovative V2O5-CeO2/TaTiOx catalyst for NOx removal was prepared in this study. The influences of Ce and Ta in the V2O5-CeO2/TaTiOx catalyst on the SCR performance and physicochemical properties were investigated. The V2O5-CeO2/TaTiOx catalyst not only exhibited excellent SCR activity in a wide temperature window, but also presented strong resistance to H2O and SO2 at 275 ℃. A series of characterization methods was used to study the catalysts, including H2-temperature programmed reduction, X-ray photoelectron spectroscopy, NH3-temperature programmed desorption, etc. It was discovered that a synergistic effect existed between Ce and Ta species. The introduction of Ce and Ta enlarged the specific surface area, increased the amount of acid sites and the ratio of Ce3+, (V3++V4+) and Oα, and strengthened the redox capability which were related to synergistic effect between Ce and Ta species, significantly improving the NH3-SCR activity.

In-Depth Mass Spectrometry Study of Vanadium(IV) Complexes with Model Peptides.

Investigating the speciation of vanadium complexes in the presence of potential biomolecular targets under physiological conditions remains challenging, and further experimental techniques are needed to better understand the mechanism of action of potential metallodrugs. The interaction of two model peptides (angiotensin I and angiotensin II) with three well-known oxidovanadium(IV) compounds with antidiabetic and/or anticancer activity, [VIVO(pic)2(H2O)], [VIVO(ma)2], and [VIVO(dhp)2] (where pic, ma, and dhp are picolinate, maltolate, and 1,2-dimethyl-3-hydroxy-4(1H)-pyridinonate anions, respectively), was investigated by ESI-MS/MS (electrospray ionization tandem mass spectrometry) and complemented by EPR (electron paramagnetic resonance) spectroscopy measurements and theoretical calculations at the DFT (density functional theory) level. The results demonstrated that vanadium-peptide bonds are preserved after HCD (higher energy collisional dissociation) fragmentation, allowing for the identification of binding sites through a detailed analysis of the fragmentation spectra. Angiotensin I (AT1) and angiotensin II (AT2) exhibited different coordination behaviors. AT1, with two His residues (His6, His9), prefers to form [AT1 + VOL] adducts with both histidine residues coordinated to the metal ion, while AT2, which has only His6, can bind the metal in a monodentate fashion, forming also [AT2 + VOL2] adducts. Insights from this study pave the way to ESI-MS/MS investigations of more complex systems, including target proteins and further development of vanadium-based drugs.

A refreshing approach to understanding the action on DNA of vanadium (IV) and (V) complexes derived from the anticancer VCp2Cl2.

A computational study based on derivatives of the anticancer VCp2Cl2 compound and their interaction with representative models of deoxyribonucleic acid (DNA) is presented. The derivatives were obtained by substituting the cyclopentadienes of VCp2Cl2 with H2O, NH3, OH-, Cl-, O2- and C2O42- ligands. The oxidation states IV and V of vanadium were considered, so a total of 20 derivative complexes are included. The complexes interactions with DNA were studied using two different models, the first model considers the interactions of the complexes with the pair Guanine-Cytosine (G-C) and the second involves the interaction of the complexes with adjacent pairs, that is, d(GG). This study compares methodologies based on density functional theory with coupled cluster like calculations (DLPNO-CCSD(T)), the gold standard of electronic structure methods. Furthermore, the change in the electron density of the hydrogen bonds that keep bonded the G-C pair and d(GG) pairs, due to the presence of vanadium (IV) and (V) complexes is rationalize. To this aim, quantities obtained from the topology of the electron densities are inspected, particularly the value of the electron density at the hydrogen bond critical points. The approach allowed to identify vanadium complexes that lead to significant changes in the hydrogen bonds indicated above, a key aspect in the understanding, development, and proposal of mechanisms of action between metal complexes and DNA.

Enhanced Electrochemical Sensing of Oxalic Acid Based on VS2 Nanoflower-Decorated Glassy Carbon Electrode Prepared by Hydrothermal Method.

Oxalic acid (OA) is a predominant constituent in kidney stones, contributing to 70-80% of all cases. Rapid detection of OA is vital for the early diagnosis and treatment of kidney stone conditions. This work introduces a novel electrochemical sensing approach for OA, leveraging vanadium disulfide (VS2) nanoflowers synthesized via hydrothermal synthesis. These VS2 nanoflowers, known for their excellent electrocatalytic properties and large surface area, are used to modify glassy carbon electrodes for enhanced OA sensing. The proposed OA sensor exhibits high sensitivity and selectivity across a wide linear detection range of 0.2-20 µM, with an impressively low detection limit of 0.188 µM. The practicality of this sensor was validated through interference studies, offering a promising tool for the early diagnosis and monitoring of kidney stone diseases.

Synthesis and Characterization of Vanadium Nitride/Carbon Nanocomposites.

The present work focuses on the synthesis of a vanadium nitride (VN)/carbon nanocomposite material via the thermal decomposition of vanadyl phthalocyanine (VOPC). The morphology and chemical structure of the synthesized compounds were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoemission spectroscopy (XPS). The successful syntheses of the VOPC and non-metalated phthalocyanine (H2PC) precursors were confirmed using FTIR and XRD. The VN particles present a needle-like morphology in the VN synthesized by the sol-gel method. The morphology of the VN/C composite material exhibited small clusters of VN particles. The XRD analysis of the thermally decomposed VOPC indicated a mixture of amorphous carbon and VN nanoparticles (VN(TD)) with a cubic structure in the space group FM-3M consistent with that of VN. The XPS results confirmed the presence of V(III)-N bonds in the resultant material, indicating the formation of a VN/C nanocomposite. The VN/C nanocomposite synthesized through thermal decomposition exhibited a high carbon content and a cluster-like distribution of VN particles. The VN/C nanocomposite was used as an anode material in LIBs, which delivered a specific capacity of 307 mAh g-1 after 100 cycles and an excellent Coulombic efficiency of 99.8 at the 100th cycle.

Engineering a two-dimensional metal-carbon nanozyme-based portable paper-based colorimetric chip for onsite and visual analysis of pyrophosphate.

Sensitive and accurate analysis of pyrophosphate (PPi) is of great importance for preventing health hazard in environment. Nevertheless, most of sensors focus on sensitivity and selectivity, but practicality is also a significant quota. How to reconciling sensitivity, selectivity and practicability in one single sensor is desirable but remains challenging. Here, we created a novel metal-carbon nanozyme V2O5@C with two-dimensional (2D) morphology and high yet exclusive peroxidase (POD)-like activity via a glucose and NH4NO4-co-directed avenue, and further showed its application in constructing a portable and disposable paper-based analytical chip (PA-chip) for rapid, visual and onsite analysis of PPi. PPi etched V2O5 to prevent the decomposition of H2O2 into ·OH, resulting in weakened POD-like activity. In comparison with PPi deficiency, colorless TMB couldn't be oxidized into oxidized TMB with a dropped absorption at 652 nm. Therefore, obviously shallowed blue color on PA-chip surface was recorded, and demonstrated a negative relationship with PPi dosage, enabling rapid and visual detection of PPi with a limit of detection of 2.6 nM. This study demonstrated the burgeoning applications of nanozymes with POD-like activity in construction of PA-chips for PPi and will quicken the advancement of practical sensors, guaranteeing environmental safety.

Disposal of spent V2O5-WO3/TiO2 catalysts: A regeneration principle based on structure-activity relationships from carrier transformations.

Characterization and evaluation of hazardous spent V2O5-WO3/TiO2 catalysts are critical to determining their treatment or final disposal. This study employs a thermal approach to simulate the preparation of spent catalysts derived from commercial V2O5-WO3/TiO2 catalysts and investigate the structure-activity relationship of the carrier changes during the deactivation process. The results indicate that the catalyst carrier undergoes two processes: an increase in grain size and a transformation in crystal structure. Both structural and catalytic investigations demonstrate that the grain size for catalyst deactivation is 24.62 nm, and the formation of CaWO4 occurs before the crystalline transformation. The specific surface area is susceptible to an increase in grain size. The reactions of selective catalytic reduction involve the participation of both Brønsted acid and Lewis acid sites. The deactivation process of the carrier initially affects Brønsted acid sites, followed by a reduction in Lewis acid sites, resulting in a decline in NH3 adsorption capacity and oxidation. Correlation analysis reveals that changes in the physicochemical properties of the catalyst reduce the NO conversion, with the order being The grain size > Total acid amount > The surface area. It is recommended to recycle the spent catalyst if the carrier grain size is less than 25 nm. The findings of this investigation contribute to expanding the database for evaluating and understanding the physicochemical properties of spent catalysts for disposal.

Mxene-bpV plays a neuroprotective role in cerebral ischemia-reperfusion injury by activating the Akt and promoting the M2 microglial polarization signaling pathways.

Studies have shown that the inhibition of phosphatase and tensin homolog deleted on chromosome 10 (PTEN)was neuroprotective against ischemia/reperfusion(I/R) injury. Bisperoxovanadium (bpV), a derivative of vanadate, is a well-established inhibitor of PTEN. However, its function islimited due to its general inadequacy in penetrating cell membranes. Mxene(Ti3C2Tx) is a novel two-dimensional lamellar nanomaterial with an excellent ability to penetrate the cell membrane. Yet, the effects of this nanomaterial on nervous system diseases have yet to be scrutinized. Here, Mxene(Ti3C2Tx) was used for the first time to carry bpV(HOpic), creating a new nanocomposite Mxene-bpV that was probed in a cerebral I/R injury model. The findings showed that this synthetic Mxene-bpV was adequately stable and can cross the cell membraneeasily. We observed that Mxene-bpV treatment significantly increased the survival rate of oxygen glucose deprivation/reperfusion(OGD/R)--insulted neurons, reduced infarct sizes and promoted the recovery of brain function after mice cerebral I/R injury. Crucially, Mxene-bpV treatment was more therapeutically efficient than bpV(HOpic) treatment alone over the same period. Mechanistically, Mxene-bpV inhibited the enzyme activity of PTEN in vitro and in vivo. It also promoted the expression of phospho-Akt (Ser473) by repressing PTEN and then activated the Akt pathway to boost cell survival. Additionally, in PTEN transgenic mice, Mxene-bpV suppressed I/R-induced inflammatory response by promoting M2 microglial polarization through PTEN inhibition. Collectively, the nanosynthetic Mxene-bpV inhibited PTEN' enzymatic activity by activating Akt pathway and promoting M2 microglial polarization, and finally exerted neuroprotection against cerebral I/R injury.

Characterization and biological prospects of various calcined temperature-V2O5 nanoparticles synthesized by Citrus hystrix fruit extract.

In this study, a simple green synthesis of vanadium pentoxide nanoparticles (VNPs) was prepared by the extract of Kaffir lime fruit (Citrus hystrix) as a green reducing and stabilizing agent, along with the investigation of calcination temperature was carried out at 450 and 550 °C. It was affirmed that, at higher temperature (550 °C), the VNPs possessed a high degree crystalline following the construction of (001) lattice diffraction within an increase in crystalline size from 47.12 to 53.51 nm, although the band gap of the materials at 450 °C was lower than that of the VNPs-550 (2.53 versus 2.66 eV, respectively). Besides, the materials were assessed for the potential bioactivities toward antibacterial, antifungal, DNA cleavage, anti-inflammatory, and hemolytic performances. As a result, the antibacterial activity, with minimal inhalation concentration (MIC) < 6.25 µg/mL for both strains, and fungicidal one of the materials depicted the dose-dependent effects. Once, both VNPs exhibited the noticeable efficacy of the DNA microbial damage, meanwhile, the outstanding anti-inflammatory agent was involved with the IC50 of 123.636 and 227.706 µg/mL, accounting for VNPs-450 and VNPs-550, respectively. Furthermore, this study also demonstrated the hemolytic potential of the VNPs materials. These consequences declare the prospects of the VNPs as the smart and alternative material from the green procedure in biomedicine.

Galvanic Replacement Synthesis of VOx@EGaIn-PEG Core-Shell Nanohybrids for Peroxidase Mimics.

The development of high-performance biosensors is a key focus in the nanozyme field, but the current limitations in biocompatibility and recyclability hinder their broader applications. Herein, we address these challenges by constructing core-shell nanohybrids with biocompatible poly(ethylene glycol) (PEG) modification using a galvanic replacement reaction between orthovanadate ions and liquid metal (LM) (VOx@EGaIn-PEG). By leveraging the excellent charge transfer properties and the low band gap of the LM surface oxide, the VOx@EGaIn-PEG heterojunction can effectively convert hydrogen peroxide into hydroxyl radicals, demonstrating excellent peroxidase-like activity and stability (Km = 490 µM, vmax = 1.206 µM/s). The unique self-healing characteristics of LM further enable the recovery and regeneration of VOx@EGaIn-PEG nanozymes, thereby significantly reducing the cost of biological detection. Building upon this, we developed a nanozyme colorimetric sensor suitable for biological systems and integrated it with a smartphone to create an efficient quantitative detection platform. This platform allows for the convenient and sensitive detection of glucose in serum samples, exhibiting a good linear relationship in the range of 10-500 µM and a detection limit of 2.35 µM. The remarkable catalytic potential of LM, combined with its biocompatibility and regenerative properties, offers valuable insights for applications in catalysis and biomedical fields.

Effect of vanadium and tungsten loading order on the denitration performance of F-doped V2O5-WO3/TiO2 catalysts.

F-doped V2O5-WO3/TiO2 catalyst has been confirmed to have excellent denitration activity at low temperatures. Since the V2O5-WO3/TiO2 catalyst is a structure-sensitive catalyst, the loading order of V2O5 and WO3 may affect its denitration performance. In this paper, a series of F-doped V2O5-WO3/TiO2 catalysts with different V2O5 and WO3 loading orders were synthesized to investigate the effect of denitration performance at low temperatures. It was found that the loading orders led to significant gaps in denitration performance in the range of 120-240 °C. The results indicated loading WO3 first better utilized the oxygen vacancies on the TiF carrier promoting the generation of reduced vanadium species. In addition, loading WO3 first facilitated the dispersion of V2O5 thus enhanced the NH3 adsorption capacity of VWTiF. In situ DRIFT verified the rapid reaction between NO2, nitrate, and nitrite species and adsorbed NH3 over the VWTiF, confirming that the NH3 selective catalytic reduction (NH3-SCR) reaction over VWTiF at 240 °C proceeded by the Langmuir-Hinshelwood (L-H) mechanism. This research established the constitutive relationship between the loading order of V2O5 and WO3 and the denitration performance of the F-doped VWTi catalyst providing insights into the catalyst design process.

Design of cobalt-doped graphene quantum dot-decorated vanadium pentoxide nanosheet-based Off-On fluorescent sensor system for tiopronin sensing.

Despite the high medicinal value of tiopronin, there are substantial adverse effects such as yellow skin, yellow eyes, muscle aches, etc. Therefore, there is a huge necessity to identify tiopronin using advanced sensors in provided samples. Recently, the preference for graphene quantum dots (GQDs) and inorganic nanomaterial-based fluorescent sensors for the detection of pharmaceuticals has been extensively documented due to their plentiful advantages. Therefore, in this work, the cobalt-doped GQDs decorated vanadium pentoxide nanosheet-based fluorescence switch 'Off-On' sensor (Co-GQDs@V2O5-NS) was designed for highly sensitive and selective detection of tiopronin. Briefly, the green synthesis of highly fluorescent Co-GQDs was carried out using a hydrothermal method. Meanwhile, the synthesis of V2O5-NS was synthesized using the liquid exfoliation method. The synthesis of Co-GQDs@V2O5-NS was accomplished wherein Co-GQDs adsorbed on the surface of V2O5-NS that offered the quenching of fluorescence of Co-GQDs. Afterward, the addition of tiopronin into the quenched probe disclosed the proportional recovery of fluorescence of Co-GQDs. Here, the addition of tiopronin provides the decomposition of V2O5-NS and conversion into the V4+ that aids in releasing the quenched fluorescence of Co-GQDs. The limit of detection and linearity range for tiopronin was found to be 1.43 ng/mL and 10-700 ng/mL, respectively. Moreover, it demonstrated high selectivity, good stability at experimental conditions, and practicality in analyzing tiopronin in spiked sample analysis. Hence, the designed Co-GQDs@V2O5-NS nanosized sensor enables high sensitivity, selectivity, simplicity, label-free, and eco-friendly tiopronin recognition. In the future, the utility of Co-GQDs@V2O5-NS can open a new door for sensing tiopronin in provided samples.

Evaluation of sensitivity of Extended Gate Field Effect Transistor -biosensor based on V2O5/GOx for glucose detection.

The sensing modified electrode was prepared using glucose oxidase immobilized onto vanadium pentoxide xerogel with glass/FTO as support electrode to evaluate the possibility to construct a V2O5/GOx Extended Gate Field Effect Transistor biosensor. Previously, our studies exhibited a sensitivity of V2O5 of 58.1 mV/pH. The use of Nafion® onto V2O5/GOx caused a decrease of mass loss after several cycles compared to the modified electrode without Nafion® during the EQCM and cyclic voltammetrics studies. Electrical characterization of V2O5/GOx demonstrated a tendency to stability after 200 s as a function of applied current. In presence of glucose and in different pH, the current decreased when the glucose concentration increased due to the lower active sites of enzyme. After ten voltammetric cycles, the total charge tends to structural stability. In pH = 5.0, the modified electrode based on V2O5/GOx Extended Gate Field Effect Transistor presented more tendency to sensitivity in different concentration of glucose.

Vanadium Compounds with Antidiabetic Potential.

Over the last four decades, vanadium compounds have been extensively studied as potential antidiabetic drugs. With the present review, we aim at presenting a general overview of the most promising compounds and the main results obtained with in vivo studies, reported from 1899-2023. The chemistry of vanadium is explored, discussing the importance of the structure and biochemistry of vanadate and the impact of its similarity with phosphate on the antidiabetic effect. The spectroscopic characterization of vanadium compounds is discussed, particularly magnetic resonance methodologies, emphasizing its relevance for understanding species activity, speciation, and interaction with biological membranes. Finally, the most relevant studies regarding the use of vanadium compounds to treat diabetes are summarized, considering both animal models and human clinical trials. An overview of the main hypotheses explaining the biological activity of these compounds is presented, particularly the most accepted pathway involving vanadium interaction with phosphatase and kinase enzymes involved in the insulin signaling cascade. From our point of view, the major discoveries regarding the pharmacological action of this family of compounds are not yet fully understood. Thus, we still believe that vanadium presents the potential to help in metabolic control and the clinical management of diabetes, either as an insulin-like drug or as an insulin adjuvant. We look forward to the next forty years of research in this field, aiming to discover a vanadium compound with the desired therapeutic properties.

Enantiopure chiroptical probes for circular dichroism and absorbance based detection of nerve gas simulants.

A series of oxovanadium(V) compounds 1-4 were prepared and explored as stereodynamic chiroptical probes to detect a simulant of sarin known as diethyl chlorophosphate (DCP) without any interference from the competing analytes. Simultaneous CD cum UV/vis based bimodal instant recognition of DCP using optically active probes is unprecedented. Upon fabricating the vanadium compound with a polymer has yielded a chiroptical membrane, which showed a change in its dichroic as well as colorimetric signals on interaction with DCP vapour at 1 ppm. EPR and UV/vis studies revealed an irreversible change of the CD-active V(V) to the CD-silent ternary V(V) species in presence of DCP via a transient V(IV) species. Nucleophilic attack of the alkoxo oxygen of 1-4 to the electrophilic P atom of DCP resulted in the formation of ternary V(V) compounds as confirmed by 51V/31P NMR.

Study on the cytotoxic, antimetastatic and albumin binding properties of the oxidovanadium(IV) chrysin complex. Structural elucidation by computational methodologies.

We have previously synthesized and characterized the chrysin coordination complex with the oxidovanadium(IV) cation (VIVO(chrys)2) and characterized in ethanolic solution and in solid state. Because suitable single crystals for X-ray diffraction determinations could not be obtained, in the present work, we elucidate the geometrical parameters of this complex by computational methodologies. The optimization and vibrational investigation were carried out both in ethanolic solution and in gas phase. The computational results support the experimentally proposed geometries of the VIVO(chrys)2 complex, thus leading to the conclusion that the complex exists as conformers with trans-octahedral geometry in ethanolic solution and as conformers with cis-octahedral geometry in the solid state. The complex also exists as conformers with trans-octahedral geometry in aqueous media. The active species formed after dissolution in DMSO showed anticancer and antimetastatic behavior in human lung cell line A549 with moderate binding (Kaca. 105 M-1) to bovine serum albumin (BSA). The interaction through hydrogen bonding and van der Waals forces resulted in a spontaneous process. Site marker competitive experiments showed binding sites for chrysin mainly located in site II (subdomain IIIA) and in site I (subdomain IIIA) for the complex. FT-IR spectral measurements showed evidences of the alterations of protein secondary structure in the presence of chrysin and VIVO(chrys)2.

Electrochemical Performance of Na3V2(PO4)2F3 Electrode Material in a Symmetric Cell.

A NASICON-based Na3V2(PO4)2F3 (NVPF) cathode material is reported herein as a potential symmetric cell electrode material. The symmetric cell was active from 0 to 3.5 V and showed a capacity of 85 mAh/g at 0.1 C. With cycling, the NVPF symmetric cell showed a very long and stable cycle life, having a capacity retention of 61% after 1000 cycles at 1 C. The diffusion coefficient calculated from cyclic voltammetry (CV) and the galvanostatic intermittent titration technique (GITT) was found to be ~10-9-10-11, suggesting a smooth diffusion of Na+ in the NVPF symmetric cell. The electrochemical impedance spectroscopy (EIS) carried out during cycling showed increases in bulk resistance, solid electrolyte interphase (SEI) resistance, and charge transfer resistance with the number of cycles, explaining the origin of capacity fade in the NVPF symmetric cell. Finally, the postmortem analysis of the symmetric cell after 1000 cycles at a 1 C rate indicated that the intercalation/de-intercalation of sodium into/from the host structure occurred without any major structural destabilization in both the cathode and anode. However, there was slight distortion in the cathode structure observed, which resulted in capacity loss of the symmetric cell. The promising electrochemical performance of NVPF in the symmetric cell makes it attractive for developing long-life and cost-effective batteries.

Water-Soluble Dioxidovanadium(V) Complexes of Aroylhydrazones: DNA/BSA Interactions, Hydrophobicity, and Cell-Selective Anticancer Potential.

Five new anionic aqueous dioxidovanadium(V) complexes, [{VO2L1,2}A(H2O)n]α (1-5), with the aroylhydrazone ligands pyridine-4-carboxylic acid (3-ethoxy-2-hydroxybenzylidene)hydrazide (H2L1) and furan-2-carboxylic acid (3-ethoxy-2-hydroxybenzylidene)hydrazide (H2L2) incorporating different alkali metals (A = Na+, K+, Cs+) as countercation were synthesized and characterized by various physicochemical techniques. The solution-phase stabilities of 1-5 were determined by time-dependent NMR and UV-vis, and also the octanol/water partition coefficients were obtained by spectroscopic techniques. X-ray crystallography of 2-4 confirmed the presence of vanadium(V) centers coordinated by two cis-oxido-O atoms and the O, N, and O atoms of a dianionic tridentate ligand. To evaluate the biological behavior, all complexes were screened for their DNA/protein binding propensity through spectroscopic experiments. Finally, a cytotoxicity study of 1-5 was performed against colon (HT-29), breast (MCF-7), and cervical (HeLa) cancer cell lines and a noncancerous NIH-3T3 cell line. The cytotoxicity was cell-selective, being more active against HT-29 than against other cells. In addition, the role of hydrophobicity in the cytotoxicity was explained in that an optimal hydrophobicity is essential for high cytotoxicity. Moreover, the results of wound-healing assays indicated antimigration in case of HT-29 cells. Remarkably, 1 with an IC50 value of 5.42 ± 0.15 µM showed greater activity in comparison to cisplatin against the HT-29 cell line.

Effects of Vanadyl Complexes with Acetylacetonate Derivatives on Non-Tumor and Tumor Cell Lines.

Vanadium has a good therapeutic potential, as several biological effects, but few side effects, have been demonstrated. Evidence suggests that vanadium compounds could represent a new class of non-platinum, metal antitumor agents. In the present study, we aimed to characterize the antiproliferative activities of fluorescent vanadyl complexes with acetylacetonate derivates bearing asymmetric substitutions on the ß-dicarbonyl moiety on different cell lines. The effects of fluorescent vanadyl complexes on proliferation and cell cycle modulation in different cell lines were detected by ATP content using the CellTiter-Glo Luminescent Assay and flow cytometry, respectively. Western blotting was performed to assess the modulation of mitogen-activated protein kinases (MAPKs) and relevant proteins. Confocal microscopy revealed that complexes were mainly localized in the cytoplasm, with a diffuse distribution, as in podocyte or a more aggregate conformation, as in the other cell lines. The effects of complexes on cell cycle were studied by cytofluorimetry and Western blot analysis, suggesting that the inhibition of proliferation could be correlated with a block in the G2/M phase of cell cycle and an increase in cdc2 phosphorylation. Complexes modulated mitogen-activated protein kinases (MAPKs) activation in a cell-dependent manner, but MAPK modulation can only partly explain the antiproliferative activity of these complexes. All together our results demonstrate that antiproliferative effects mediated by these compounds are cell type-dependent and involve the cdc2 and MAPKs pathway.

Vanadium-Flavonoid Complexes: A Promising Class of Molecules for Therapeutic Applications.

Several reports have revealed the superior biological activity of metal ion-flavonoid complexes when compared with the parent flavonoid. Among the different metal ions explored, vanadium and its compounds are in the forefront because of their anticancer and antidiabetic properties. However, the toxicity of vanadium-based ions and their inorganic derivatives limits their therapeutic applications. Complexation of vanadium with flavonoids not only reduces its adverse effects but also augments its biological activity. This Review discusses the nature of coordination in vanadium-flavonoid complexes, their structure-activity correlations, with special emphasis on their therapeutic activities. Several investigations suggest that the superior biological activity of vanadium complexes arise because of their ability to regulate metabolic pathways distinct from those acted upon by vanadium alone. These studies serve to decipher the underlying molecular mechanism of vanadium-flavonoid complexes that can be explored further for generating a series of novel compounds with improved pharmacological and therapeutic performance.