Synthesis, characterization, and biological activity of oxovanadium(IV) complexes with polyalcohols

Synthesis and encapsulation of V(IV,V) compounds in silica nanoparticles targeting development of antioxidant and antiradical nanomaterials

The quest for effective treatments of oxidative stress has concentrated over the years on new nanomaterials with improved antioxidant and antiradical activity, thereby attracting broad research interest. In that regard, research efforts in our lab were launched to pursue such hybrid materials involving a) synthesis of silica gel matrices, b) evaluation of the suitability of atoxic matrices as potential carriers for the controlled release of V(IV)(VOSO₄), V(V)(NaVO₃) compounds and a newly synthesized heterometallic lithium-vanadium(IV,V) tetranuclear compound containing vanadium-bound hydroxycarboxylic 1,3-diamine-2-propanol-N,N,N',N'-tetraacetic acid (DPOT), and c) investigation of structural and textural properties of silica nanoparticles (NPs) by different and complementary characterization techniques, inquiring into the nature of the encapsulated vanadium species and their interaction with the siloxane matrix, collectively targeting novel antioxidant and antiradical nanomaterials biotechnology. The physicochemical characterization of the vanadium-loaded SiO₂ NPs led to the formulation of optimized material configuration linked to the delivery of the encapsulated antioxidant-antiradical load. Entrapment and drug release studies showed a) the competence of hybrid nanoparticles with respect to encapsulation efficiency of the vanadium compound (concentration dependence), b) congruence with the physicochemical features determined, and c) a well-defined release profile of NP load. Antioxidant properties and the free radical scavenging capacity of the new hybrid materials (containing VOSO₄, NaVO₃, and V-DPOT) were demonstrated through a) 2-diphenyl-1-picrylhydrazyl (DPPH) free radical, and b) intracellular-extracellular reactive oxygen species (ROS) assays, through UV-Visible spectroscopy techniques, collectively showing that the hybrid silica NPs (empty-loaded) could serve as an efficient platform for nanodrug formulations counteracting oxidative stress.

Role of ERK/NFκB in vanadium (IV) oxide mediated osteoblast differentiation in C3H10t1/2 cells

Vanadium (V) compounds are reported to have insulin mimicking action, which render them to show excellent osteogenic activity. In the current study we investigated the effect of various vanadium compounds on osteoblast differentiation of mouse mesenchymal stem cells, C3H10t1/2 cells, and analyzed the underlying mechanism of vanadium for this action. Our data showed that treatment of C3H10t1/2 cells with V (IV) oxide complex (at 7-25 μM concentrations) induced osteoblast differentiation maximally as compared to V2O5. On the other hand, ammonium vanadate was found to dampen the osteoblast differentiation process. Based on this data, V (IV) oxide was investigated further to analyze its probable mode of action as an osteoblastic agent. The key factors implicated in osteoblast differentiation i.e., NFκB, ERK ½, AP1 and CRE were examined in response to V (IV) oxide exposure. Exposure to V (IV) oxide caused 2- and 5-folds induction of luciferase activities in cells transfected with SRE-luc and NFκB-luc reporter vectors respectively (p < 0.05). Further, exposure to V (IV) oxide enhanced the phosphorylation of ERK ½, IκB and NFκBp65 proteins. In addition, RT-PCR analysis, alizarin red staining and immunoblot analysis showed that inhibition of osteoblast differentiation in presence of PD98059 and parthenolide (inhibitors of ERK and NFκB pathways respectively) was rescued in presence of V (IV) oxide. These results suggest that V (IV) oxide up regulates osteoblast differentiation through ERK and NFκB pathways and hence could be utilized as an agent for bone formation after further analysis and validation.

Impact of vanadium complexes treatment on the oxidative stress factors in wistar rats plasma

The aim of this study was to investigate the clinical efficacy of vanadium complexes on triglycerides (TG), total cholesterol (Chol), uric acid (UA), urea (U), and antioxidant parameters: nonenzymatic (FRAP—ferric reducing ability of plasma, and reduced glutathione—GSH) and enzymatic (glutathione peroxidase—GPx, catalase—CAT, and GPx/CAT ratio) activity in the plasma of healthy male Wistar rats. Three vanadium complexes: [VO(bpy)₂]SO₄·2H₂O, [VO(4,4′Me₂bpy)₂]SO₄·2H₂O, and Na[VO(O₂)₂(bpy)]·8H₂O are administered by gavage during 5 weeks in two different diets such as control (C) and high fatty (F) diets. Changes of biochemical and antioxidants parameters are measured in plasma. All three vanadium complexes statistically decrease the body mass growth in comparison to the control and fatty diet. In plasma GSH was statistically increased in all vanadium complexes-treated rats from control and fatty group in comparison to only control group. Calculated GPX/CAT ratio was the highest in the control group in comparison to others.

Synthesis, characterization, antitumoral and osteogenic activities of quercetin vanadyl(IV) complexes

The development of new vanadium derivatives with organic ligands, which improve the beneficial actions (insulin-mimetic, antitumoral) and decrease the toxic effects, is of great interest. A good candidate for the generation of a new vanadium compound is the flavonoid quercetin because of its own anticarcinogenic effect. The complex [VO(Quer)(2)EtOH]( n ) (QuerVO) has been synthesized and characterized by means of different spectroscopic techniques (UV-vis, Fourier transform IR, electron paramagnetic resonance) and its magnetic and stability properties. The inhibitory effect on bovine alkaline phosphatase (ALP) activity has been tested for the free ligand, the complex as well as for the vanadyl(IV) (comparative purposes). The biological activity of the complex on the proliferation of two osteoblast-like cells in culture, a normal one (MC3T3E1) and a tumoral one (UMR106), has been compared with that of the vanadyl(IV) cation and quercetin. The differentiation osteoblast markers ALP specific activity and collagen synthesis have been also tested. In addition, the effect of QuerVO on the activation of the extracellular regulated kinase (ERK) pathway is reported. The bone antitumoral effect of quercetin alone was established with the cell proliferation assays (it inhibits the proliferation of the tumoral cells and does not exert any effect on the normal osteoblasts). Moreover, the complex exerts osteogenic effects since it stimulates the type I collagen production and is a weak inhibitory agent upon ALP activity. Finally, QuerVO stimulated the ERK phosphorylation in a dose-response manner and this activation seems to be involved as one of the possible mechanisms for the biological effects of the complex.