Vanadium in diabetes: 100 years from Phase 0 to Phase I

Hydrazone-flavonol based oxidovanadium(V) complexes: Synthesis, characterization and antihyperglycemic activity of chloro derivative in vivo

Wet synthesis approach afforded four new heteroleptic mononuclear neutral diamagnetic oxidovanadium(V) complexes, comprising salicylaldehyde-based 2-furoic acid hydrazones and a flavonol coligand of the general composition [VO(fla)(L-ONO)]. The complexes were comprehensively characterized, including chemical analysis, conductometry, infrared, electronic, and mass spectroscopy, as well as 1D 1H and proton-decoupled 13C(1H) NMR spectroscopy, alongside extensive 2D 1H1H COSY, 1H13C HMQC, and 1H13C HMBC NMR analyses. Additionally, the quantum chemical properties of the complexes were studied using Gaussian at the B3LYP, HF, and M062X levels on the 6-31++g(d,p) basis sets. The interaction of these hydrolytically inert vanadium complexes and the BSA was investigated through spectrofluorimetric titration, synchronous fluorimetry, and FRET analysis in a temperature-dependent manner, providing valuable thermodynamic insights into van der Waals interactions and hydrogen bonding. Molecular docking was conducted to gain further understanding of the specific binding sites of the complexes to BSA. Complex 2, featuring a 5-chloro-substituted salicylaldehyde component of the hydrazone, was extensively examined for its biological activity in vivo. The effects of complex administration on biochemical and hematological parameters were evaluated in both healthy and diabetic Wistar rats, revealing antihyperglycemic activity at millimolar concentration. Furthermore, histopathological analysis and bioaccumulation studies of the complex in the brain, kidneys, and livers of healthy and diabetic rats revealed the potential for further development of vanadium(V) hydrazone complexes as antidiabetic and insulin-mimetic agents.

A Non-Toxic Binuclear Vanadium(IV) Complex as Insulin Adjuvant Improves the Glycemic Control in Streptozotocin-Induced Diabetic Rats

Diabetes mellitus (DM) complications are a burden to health care systems due to the associated consequences of poor glycemic control and the side effects of insulin therapy. Recently. adjuvant therapies, such as vanadium compounds, have gained attention due to their potential to improve glucose homeostasis in patients with diabetes. In order to determine the anti-diabetic and antioxidant effects of the oxidovanadium(IV) complex (Et3NH)2[{VO(OH}2)(ox)2(µ-ox)] or Vox2), rats with streptozotocin (STZ)-induced diabetes were treated with 30 and 100 mg/kg of Vox2, orally administered for 12 days. Vox2 at 100 mg/kg in association with insulin caused a 3.4 times decrease in blood glucose in STZ rats (424 mg/dL), reaching concentrations similar to those in the normoglycemic animals (126 mg/dL). Compared to insulin alone, the association with Vox2 caused an additional decrease in blood glucose of 39% and 65% at 30 and 100 mg/kg, respectively, and an increased pancreatic GSH levels 2.5 times. Vox2 alone did not cause gastrointestinal discomfort, diarrhea, and hepatic or renal toxicity and was not associated with changes in blood glucose level, lipid profile, or kidney or liver function. Our results highlight the potential of Vox2 in association with insulin in treating diabetes.

Vanadium Complexes with Thioanilide Derivatives of Amino Acids: Inhibition of Human Phosphatases and Specificity in Various Cell Models of Metabolic Disturbances

In the text, the synthesis and characteristics of the novel ONS-type vanadium (V) complexes with thioanilide derivatives of amino acids are described. They showed the inhibition of human protein tyrosine phosphatases (PTP1B, LAR, SHP1, and SHP2) in the submicromolar range, as well as the inhibition of non-tyrosine phosphatases (CDC25A and PPA2) similar to bis(maltolato)oxidovanadium(IV) (BMOV). The ONS complexes increased [14C]-deoxy-D-glucose transport into C2C12 myocytes, and one of them, VC070, also enhanced this transport in 3T3-L1 adipocytes. These complexes inhibited gluconeogenesis in hepatocytes HepG2, but none of them decreased lipid accumulation in the non-alcoholic fatty liver disease model using the same cells. Compared to the tested ONO-type vanadium complexes with 5-bromosalicylaldehyde and substituted benzhydrazides as Schiff base ligand components, the ONS complexes revealed stronger inhibition of protein tyrosine phosphatases, but the ONO complexes showed greater activity in the cell models in general. Moreover, the majority of the active complexes from both groups showed better effects than VOSO4 and BMOV. Complexes from both groups activated AKT and ERK signaling pathways in hepatocytes to a comparable extent. One of the ONO complexes, VC068, showed activity in all of the above models, including also glucose utilizatiand ONO Complexes are Inhibitors ofon in the myocytes and glucose transport in insulin-resistant hepatocytes. The discussion section explicates the results within the wider scope of the knowledge about vanadium complexes.

Vanadium(V) Pyridine-Containing Schiff Base Catecholate Complexes are Lipophilic, Redox-Active and Selectively Cytotoxic in Glioblastoma (T98G) Cells

Two new series of complexes with pyridine-containing Schiff bases, [VV O(SALIEP)L] and [VV O(Cl-SALIEP)L] (SALIEP=N-(salicylideneaminato)-2-(2-aminoethylpyridine; Cl-SALIEP=N-(5-chlorosalicylideneaminato)-2-(2-aminoethyl)pyridine, L=catecholato(2-) ligand) have been synthesized. Characterization by 1 H and 51 V NMR and UV-Vis spectroscopies confirmed that: 1) most complexes form two major geometric isomers in solution, and [VV O(SALIEP)(DTB)] (DTB=3,5-di-tert-butylcatecholato(2-)) forms two isomers that equilibrate in solution; and 2) tert-butyl substituents were necessary to stabilize the reduced VIV species (EPR spectroscopy and cyclic voltammetry). The pyridine moiety within the Schiff base ligands significantly changed their chemical properties with unsubstituted catecholate ligands compared with the parent HSHED (N-(salicylideneaminato)-N'-(2-hydroxyethyl)-1,2-ethanediamine) Schiff base complexes. Immediate reduction to VIV occurred for the unsubstituted-catecholato VV complexes on dissolution in DMSO. By contrast, the pyridine moiety within the Schiff base significantly improved the hydrolytic stability of [VV O(SALIEP)(DTB)] compared with [VV O(HSHED)(DTB)]. [VV O(SALIEP)(DTB)] had moderate stability in cell culture media. There was significant cellular uptake of the intact complex by T98G (human glioblastoma) cells and very good anti-proliferative activity (IC50 6.7±0.9 μM, 72 h), which was approximately five times higher than for the non-cancerous human cell line, HFF-1 (IC50 34±10 μM). This made [VV O(SALIEP)(DTB)] a potential drug candidate for the treatment of advanced gliomas by intracranial injection.

Insulin Receptor Substrates Regulation and Clinical Responses Following Vanadium-Enriched Yeast Supplementation in Obese Type 2 Diabetic Patients: a Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Increasing evidence suggests that organic vanadium compounds are bioavailable and safe therapeutic agents with insulin-mimetic and insulin-enhancing features. The objective of the current study was to examine the effect of vanadium-enriched yeast (VEY) supplementation on the gene expression level of insulin receptor substrates and clinical manifestations of obese type 2 diabetic mellitus (T2DM) patients. In this randomized, double-blind, placebo-controlled clinical trial, 44 obese T2DM patients were randomly allocated into either VEY (0.9 mg/day vanadium pentoxide) or placebo group for 12 weeks. The mRNA expression level of protein tyrosine phosphatase 1B (PTP1B), phosphatase and tensin homolog (PTEN), mitogen-activated protein kinase (MAPK), ribosomal protein S6 kinase (S6K), and nuclear factor kappa-light-chain-enhancer of activated B cells (NFƘB) genes in the peripheral blood mononuclear cells, serum levels of metabolic parameters, anthropometric indices, as well as the quality of life, and dietary intake were collected at pre- and post-intervention phases. Analysis of covariance was performed to obtain the corresponding effect size. Results showed that VEY administration significantly decreased anthropometric indices and glycemic parameters and increased insulin sensitivity after adjusting for potential covariates (p < 0.05), in comparison to the placebo group. Additionally, VEY supplementation was significantly effective on MAPK, PTP1B, and NFƘB gene expression level, compared to the placebo group. No significant changes were noticed for dietary intake, quality of life, and lipid profile in the VEY group, compared to the placebo group. Overall, VEY supplementation can be considered as a promising safe adjunct therapy for improving anthropometric indices and glycemic parameters in T2DM patients.

Substitution Kinetics, Albumin and Transferrin Affinities, and Hypoxia All Affect the Biological Activities of Anticancer Vanadium(V) Complexes

Limited stability of most transition-metal complexes in biological media has hampered their medicinal applications but also created a potential for novel cancer treatments, such as intratumoral injections of cytotoxic but short-lived anticancer drugs. Two related V(V) complexes, [VO(Hshed)(dtb)] (1) and [VO(Hshed)(cat)] (2), where H2shed = N-(salicylideneaminato)-N'-(2-hydroxyethyl)-1,2-ethanediamine, H2dtb = 3,5-di-tert-butylcatechol, and H2cat = 1,2-catechol, decomposed within minutes in cell culture medium at 310 K (t1/2 = 43 and 9 s for 1 and 2, respectively). Despite this, both complexes showed high antiproliferative activities in triple-negative human breast cancer (MDA-MB-231) cells, but the mechanisms of their activities were radically different. Complex 1 formed noncovalent adducts with human serum albumin, rapidly entered cells via passive diffusion, and was nearly as active in a short-term treatment (IC50 = 1.9 ± 0.2 μM at 30 min) compared with a long-term treatment (IC50 = 1.3 ± 0.2 μM at 72 h). The activity of 1 decreased about 20-fold after its decomposition in cell culture medium for 30 min at 310 K. Complex 2 showed similar activities (IC50 ≈ 12 μM at 72 h) in both fresh and decomposed solutions and was inactive in a short-term treatment. The activity of 2 was mainly due to the reactions among V(V) decomposition products, free catechol, and O2 in cell culture medium. As a result, the activity of 1 was less sensitive than that of 2 to the effects of hypoxic conditions that are characteristic of solid tumors and to the presence of apo-transferrin that acts as a scavenger of V(V/IV) decomposition products in blood serum. In summary, complex 1, but not 2, is a suitable candidate for further development as an anticancer drug delivered via intratumoral injections. These results demonstrate the importance of fine-tuning the ligand properties for the optimization of biological activities of metal complexes.

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.

Interaction of Vanadium Complexes with Proteins: Revisiting the Reported Structures in the Protein Data Bank (PDB) since 2015

The structural determination and characterization of molecules, namely proteins and enzymes, is crucial to gaining a better understanding of their role in different chemical and biological processes. The continuous technical developments in the experimental and computational resources of X-ray diffraction (XRD) and, more recently, cryogenic Electron Microscopy (cryo-EM) led to an enormous growth in the number of structures deposited in the Protein Data Bank (PDB). Bioinorganic chemistry arose as a relevant discipline in biology and therapeutics, with a massive number of studies reporting the effects of metal complexes on biological systems, with vanadium complexes being one of the relevant systems addressed. In this review, we focus on the interactions of vanadium compounds (VCs) with proteins. Several types of binding are established between VCs and proteins/enzymes. Considering that the V-species that bind may differ from those initially added, the mentioned structural techniques are pivotal to clarifying the nature and variety of interactions of VCs with proteins and to proposing the mechanisms involved either in enzymatic inhibition or catalysis. As such, we provide an account of the available structural information of VCs bound to proteins obtained by both XRD and/or cryo-EM, mainly exploring the more recent structures, particularly those containing organic-based vanadium complexes.

Synthesis of a novel magnetic nanomaterial for the development of a multielemental speciation method of lead, mercury, and vanadium via HPLC-ICP MS

A new magnetic functionalized material based on graphene oxide magnetic nanoparticles named by us, M@GO-TS, was designed and characterized in order to develop a magnetic solid-phase extraction method (MSPE) to enrich inorganic and organic species of lead, mercury, and vanadium. A flow injection (FI) system was used to preconcentrate the metallic and organometallic species simultaneously, while the ultra-trace separation and determination of the selected species were achieved by high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP MS). Therefore, preconcentration and separation/determination processes were automated and conducted separately. To the best of our knowledge, this is the first method combining an online MSPE and HPLC-ICP MS for multielemental speciation. Under the optimized conditions, the enrichment factor obtained for Pb^II, trimethyllead (TML), Hg^II, methylmercury (MetHg), and V^V was 27. The calculated LOD for all studied species were as follows: 5 ng L^-1, 20 ng L^-1, 2 ng L^-1, 10 ng L^-1, and 0.4 ng L^-1, respectively. The RSD values calculated with a solution containing 0.5 μg L^-1 of all species were between 2.5 and 4.5%. The developed method was validated by analyzing Certified Reference Materials TMDA 64.3 for total concentration and also by recovery analysis of the species in human urine from volunteers and a seawater sample collected in Málaga. The t statistical test showed no significant differences between the certified and found values for TMDA 64.3. All the recoveries obtained from spiked human urine and seawater samples were close to 100%. All samples were analyzed using external calibration. The developed method is sensitive and promising for routine monitoring of the selected species in environmental waters and biological samples.

Medicinal applications of vanadium complexes with Schiff bases

Many transition metal complexes have been explored for their therapeutic properties after the discovery of cisplatin. Schiff bases have an efficient complexation tendency with the transition metals and several medicinal properties have been reported. However, fewer studies have reported the medicinal utility of vanadium and its Schiff base complexes. This paper provides a comprehensive overview of vanadium complexes with Schiff bases along with their mechanistic insight. Vanadium complexes in + 4 and + 5 oxidation states have exhibited well-defined geometry and found to be thermodynamically stable. The studies have reported the G0/G1 phase cell cycle arrest and decreased delta psi m, inducing mitochondrial membrane depolarization in cancer cell lines along with the alterations in the metabolism of the cancer cells upon dosing with the vanadium complexes. Cancer cell invasion and growth are also found to be markedly reduced by peroxo complexes of vanadium. The studies included in the review paper have been taken from leading indexing databases and focus was laid on recent reports in literature. The biological potential of vanadium complexes of Schiff bases opens new horizons for future interdisciplinary studies and investigation focussed on understanding the biochemistry of these complexes, along with designing new complexes which have better bioavailability, solubility and low or non-toxicity.

In Vitro and In Vivo Biological Activities of Dipicolinate Oxovanadium(IV) Complexes

The work is focused on anticancer properties of dipicolinate (dipic)-based vanadium(IV) complexes [VO(dipic)(N^∩N)] bearing different diimines (2-(1H-imidazol-2-yl)pyridine, 2-(2-pyridyl)benzimidazole, 1,10-phenanthroline-5,6-dione, 1,10-phenanthroline, and 2,2'-bipyridine), as well as differently 4,7-substituted 1,10-phenanthrolines. The antiproliferative effect of V(IV) systems was analyzed in different tumors (A2780, HCT116, and HCT116-DoxR) and normal (primary human dermal fibroblasts) cell lines, revealing a high cytotoxic effect of [VO(dipic)(N^∩N)] with 4,7-dimethoxy-phen (5), 4,7-diphenyl-phen (6), and 1,10-phenanthroline (8) against HCT116-DoxR cells. The cytotoxicity differences between these complexes can be correlated with their different internalization by HCT116-DoxR cells. Worthy of note, these three complexes were found to (i) induce cell death through apoptosis and autophagy pathways, namely, through ROS production; (ii) not to be cytostatic; (iii) to interact with the BSA protein; (iv) do not promote tumor cell migration or a pro-angiogenic capability; (v) show a slight in vivo anti-angiogenic capability, and (vi) do not show in vivo toxicity in a chicken embryo.

Metal-Based Anticancer Complexes and p53: How Much Do We Know?

P53 plays a key role in protecting the human genome from DNA-related mutations; however, it is one of the most frequently mutated genes in cancer. The P53 family members p63 and p73 were also shown to play important roles in cancer development and progression. Currently, there are various organic molecules from different structural classes of compounds that could reactivate the function of wild-type p53, degrade or inhibit mutant p53, etc. It was shown that: (1) the function of the wild-type p53 protein was dependent on the presence of Zn atoms, and (2) Zn supplementation restored the altered conformation of the mutant p53 protein. This prompted us to question whether the dependence of p53 on Zn and other metals might be used as a cancer vulnerability. This review article focuses on the role of different metals in the structure and function of p53, as well as discusses the effects of metal complexes based on Zn, Cu, Fe, Ru, Au, Ag, Pd, Pt, Ir, V, Mo, Bi and Sn on the p53 protein and p53-associated signaling.

A Series of Non-Oxido VIV Complexes of Dibasic ONS Donor Ligands: Solution Stability, Chemical Transformations, Protein Interactions, and Antiproliferative Activity

A series of mononuclear non-oxido vanadium(IV) complexes, [V^IV(L^1-4)₂] (1-4), featuring tridentate bi-negative ONS chelating S-alkyl/aryl-substituted dithiocarbazate ligands H₂L^1-4, are reported. All the synthesized non-oxido V^IV compounds are characterized by elemental analysis, spectroscopy (IR, UV-vis, and EPR), ESI-MS, as well as electrochemical techniques (cyclic voltammetry). Single-crystal X-ray diffraction studies of 1-3 reveal that the mononuclear non-oxido V^IV complexes show distorted octahedral (1 and 2) or trigonal prismatic (3) arrangement around the non-oxido V^IV center. EPR and DFT data indicate the coexistence of mer and fac isomers in solution, and ESI-MS results suggest a partial oxidation of [V^IV(L^1-4)₂] to [V^V(L^1-4)₂]⁺ and [V^VO₂(L^1-4)]^-; therefore, all these three complexes are plausible active species. Complexes 1-4 interact with bovine serum albumin (BSA) with a moderate binding affinity, and docking calculations reveal non-covalent interactions with different regions of BSA, particularly with Tyr, Lys, Arg, and Thr residues. In vitro cytotoxic activity of all complexes is assayed against the HT-29 (colon cancer) and HeLa (cervical cancer) cells and compared with the NIH-3T3 (mouse embryonic fibroblast) normal cell line by MTT assay and DAPI staining. The results suggest that complexes 1-4 are cytotoxic in nature and induce cell death in the cancer cell lines by apoptosis and that a mixture of V^IV, V^V, and V^VO₂ species could be responsible for the biological activity.

Vanadium(IV) complexes of salicylaldehyde-based furoic acid hydrazones: Synthesis, BSA binding and in vivo antidiabetic potential

Solution synthesis afforded five novel neutral heteroleptic octahedral paramagnetic mononuclear oxidovanadium(IV) complexes of general composition [VO(bpy)L], where L is a dianionic tridentate ONO-donor hydrazone ligand derived from 2-furoic acid hydrazide and salicylaldehyde and its 5-substituted derivatives. Characterization was carried out by elemental analysis, mass spectrometry, infrared, electron, NMR, and EPR spectroscopy, cyclic voltammetry and conductometry. The molecular and crystal structure of the complex with 5-chloro-salicylaldehyde 2-furoic acid hydrazone (2) was determined. The quantum chemical properties of the vanadium complexes were studied at B3LYP and M062X levels with the lanl2dz basis set using Gaussian. Additionally, Swiss-ADME analysis was performed and complex (4), featuring a 5-nitro substituent on the hydrazone ligand, was selected for further investigation. The effects of the in vivo application of the complex on selected biochemical parameters in healthy and diabetic Wistar rats were investigated. Strong antidiabetic effect associated with moderate hypoalbuminemia was observed. Furthermore, the interaction of complexes with BSA was studied by spectrofluorimetry. A significant conformational change of BSA in the presence of vanadium complexes was found. Synchronous fluorescence spectra revealed significant changes in the tyrosine microenvironment of BSA. The FRET analysis was also used and the non-radiative process of energy transfer is elucidated. Thermodynamic data suggest van der Waals forces and hydrogen bonding as predominant binding modes of complexes to BSA.

The antihyperglycemic and hypolipidemic activities of a sulfur-oxidovanadium(IV) complex

This study describes the synthesis, characterization, and biological activity of a new class of antidiabetic oxidovanadium(IV)-complexes with S₂O₂ coordination mode. The target complex 3,6-dithio-1,8-octanediolatooxidovanadium(IV), abbreviated as ([V^IVO(octd)]), where octd = 3,6-dithio-1,8-octanediol, is formed from the reaction between the 3,6-dithio-1,8-octanediol and vanadyl sulfate (V^IVOSO₄). The effects of treatment with ([V^IVO(octd)] on blood glucose, lipidic profile, body weight, food intake, water intake, urinary volume, glycogen levels, and biomarkers for liver toxicity were investigated using a streptozotocin (STZ)-induced diabetic Wistar rats model. The results have shown that the [V^IVO(octd)] complex caused a significant decrease in blood glucose (247.6 ± 19.3 mg/dL vs 430.1 ± 37.6 mg/dL diabetic group, p < 0.05), triglycerides (TG, 50%) and very low-density cholesterol (VLDL-C, 50%) levels in STZ-diabetic rats after 3 weeks of treatment. The [V^IVO(octd)] has shown antihyperglycemic activity in diabetic rats as well as a reduction in elevated lipid levels. Time-dependent studies using EPR and ⁵¹V NMR spectroscopy of [V^IVO(octd)] were done in aqueous solutions to determine the complex stability and species present in the oral gavage solution used for complex administration. The spectroscopic studies have shown that the antidiabetic/hypolipidemic activity could be attributed to [V^IVO(octd)], vanadium species resulting from redox processes, the hydrolysis of [V^IVO(octd)] and its decomposition products, or some combination of these factors. In summary, the oxidovanadium(IV) complex containing the S₂O₂ donor ligand has desirable antidiabetic properties eliminating the symptoms of Diabetes mellitus and its comorbidities.

Polyoxidovanadates as a pharmacological option against brain aging

The world population is aging rapidly, and chronic diseases associated are cardiometabolic syndrome, cancer, and neurodegenerative diseases. Oxidative stress and inflammation are typical hallmarks in them. Polyoxidovanadates (POVs) have shown interesting pharmacological actions against chronic diseases. This work aimed to evaluate the POV effect on hippocampal neuroinflammation, redox balance, and recognition memory in the aging of rats. Rats 18 months old were administered a daily dose of sodium metavanadate (MV), decavanadate (DV), Metformin (Metf), or MetfDeca for two months. Results showed that short-term and long-term recognition memory improved by 28 % and 16 % (DV), 19 % and 20 % (Metf), and 21 % and 27 % (MetfDeca). In hippocampi, reactive oxygen species, IL-1β, and TNF-α, after DV, Metf, and MetfDeca decreased at similar concentrations to young adult control, while lipid peroxidation substantially ameliorated. Additionally, superoxide dismutase and catalase activity increased by 41 % and 42 % (DV), 39 % and 41 % (Metf), and 75 % and 73 % (MetfDeca). POV treatments reduced Nrf2 and GFAP immunoreactivity in CA1 (70-87.5 %), CA3 (60-80 %), and DG (57-89 %). Metformin treatment showed a minor effect, while MV treatment did not improve any parameters. Although DV, Metf, and MetfDeca treatments showed similar results, POVs doses were 16-fold fewer than Metformin. In conclusion, DV and MetfDeca could be pharmacological options to reduce age-related neuronal damage.

Biological Consequences of Vanadium Effects on Formation of Reactive Oxygen Species and Lipid Peroxidation

Lipid peroxidation (LPO), a process that affects human health, can be induced by exposure to vanadium salts and compounds. LPO is often exacerbated by oxidation stress, with some forms of vanadium providing protective effects. The LPO reaction involves the oxidation of the alkene bonds, primarily in polyunsaturated fatty acids, in a chain reaction to form radical and reactive oxygen species (ROS). LPO reactions typically affect cellular membranes through direct effects on membrane structure and function as well as impacting other cellular functions due to increases in ROS. Although LPO effects on mitochondrial function have been studied in detail, other cellular components and organelles are affected. Because vanadium salts and complexes can induce ROS formation both directly and indirectly, the study of LPO arising from increased ROS should include investigations of both processes. This is made more challenging by the range of vanadium species that exist under physiological conditions and the diverse effects of these species. Thus, complex vanadium chemistry requires speciation studies of vanadium to evaluate the direct and indirect effects of the various species that are present during vanadium exposure. Undoubtedly, speciation is important in assessing how vanadium exerts effects in biological systems and is likely the underlying cause for some of the beneficial effects reported in cancerous, diabetic, neurodegenerative conditions and other diseased tissues impacted by LPO processes. Speciation of vanadium, together with investigations of ROS and LPO, should be considered in future biological studies evaluating vanadium effects on the formation of ROS and on LPO in cells, tissues, and organisms as discussed in this review.

Metformin counters oxidative stress and mitigates adverse effects of radiation exposure: An overview

Metformin (1,1-dimethylbiguanidine hydrochloride) (MF) is a drug that has long been in use for the treatment of type 2 diabetes mellitus and recently is coming into use in the radiation therapy of cancer and other conditions. Exposure to ionizing radiation disturbs the redox homeostasis of cells and causes damage to proteins, membranes, and mitochondria, destroying a number of biological processes. After irradiation, MF activates cellular antioxidant and repair systems by signaling to eliminate the harmful consequences of disruption of redox homeostasis. The use of MF in the treatment of the negative effects of irradiation has great potential in medical patients after radiotherapy and in victims of nuclear accidents or radiologic terrorism.

Vanadium Chloro-Substituted Schiff Base Catecholate Complexes are Reducible, Lipophilic, Water Stable, and Have Anticancer Activities

A hydrophobic Schiff base catecholate vanadium complex was recently discovered to have anticancer properties superior to cisplatin and suited for intratumoral administration. This [VO(HSHED)(DTB)] complex, where HSHED is N-(salicylideneaminato)-N'-(2-hydroxyethyl)-1,2-ethanediamine and the non-innocent catecholato ligand is di-t-butylcatecholato (DTB), has higher stability compared to simpler catecholato complexes. Three new chloro-substituted Schiff base complexes of vanadium(V) with substituted catecholates as co-ligands were synthesized for comparison with their non-chlorinated Schiff base vanadium complexes, and their properties were characterized. Up to four geometric isomers for each complex were identified in organic solvents using ⁵¹V and ¹H NMR spectroscopies. Spectroscopy was used to characterize the structure of the major isomer in solution and to demonstrate that the observed isomers are exchanged in solution. All three chloro-substituted Schiff base vanadium(V) complexes with substituted catecholates were also characterized by UV-vis spectroscopy, mass spectrometry, and electrochemistry. Upon testing in human glioblastoma multiforme (T98g) cells as an in vitro model of brain gliomas, the most sterically hindered, hydrophobic, and stable compound [t_1/2 (298 K) = 15 min in cell medium] was better than the two other complexes (IC₅₀ = 4.1 ± 0.5 μM DTB, 34 ± 7 μM 3-MeCat, and 19 ± 2 μM Cat). Furthermore, upon aging, the complexes formed less toxic decomposition products (IC₅₀ = 9 ± 1 μM DTB, 18 ± 3 μM 3-MeCat, and 8.1 ± 0.6 μM Cat). The vanadium complexes with the chloro-substituted Schiff base were more hydrophobic, more hydrolytically stable, more easily reduced compared to their corresponding parent counterparts, and the most sterically hindered complex of this series is only the second non-innocent vanadium Schiff base complex with a potent in vitro anticancer activity that is an order of magnitude more potent than cisplatin under the same conditions.

Current Insights on the Use of Insulin and the Potential Use of Insulin Mimetics in Targeting Insulin Signalling in Alzheimer's Disease

Alzheimer's disease (AD) and type 2 diabetes (T2D) are chronic diseases that share several pathological mechanisms, including insulin resistance and impaired insulin signalling. Their shared features have prompted the evaluation of the drugs used to manage diabetes for the treatment of AD. Insulin delivery itself has been utilized, with promising effects, in improving cognition and reducing AD related neuropathology. The most recent clinical trial involving intranasal insulin reported no slowing of cognitive decline; however, several factors may have impacted the trial outcomes. Long-acting and rapid-acting insulin analogues have also been evaluated within the context of AD with a lack of consistent outcomes. This narrative review provided insight into how targeting insulin signalling in the brain has potential as a therapeutic target for AD and provided a detailed update on the efficacy of insulin, its analogues and the outcomes of human clinical trials. We also discussed the current evidence that warrants the further investigation of the use of the mimetics of insulin for AD. These small molecules may provide a modifiable alternative to insulin, aiding in developing drugs that selectively target insulin signalling in the brain with the aim to attenuate cognitive dysfunction and AD pathologies.

Therapeutic Properties of Vanadium Complexes

Vanadium is a hard, silver-grey transition metal found in at least 60 minerals and fossil fuel deposits. Its oxide and other vanadium salts are toxic to humans, but the toxic effects depend on the vanadium form, dose, exposure duration, and route of intoxication. Vanadium is used by some life forms as an active center in enzymes, such as the vanadium bromoperoxidase of ocean algae and nitrogenases of bacteria. The structure and biochemistry of vanadate resemble those of phosphate, hence vanadate can be regarded as a phosphate competitor in a variety of biochemical enzymes such as kinases and phosphatases. In this review, we describe the biochemical pathways regulated by vanadium compounds and their potential therapeutic benefits for a range of disorders including type 2 diabetes, cancer, cardiovascular disease, and microbial pathology.

Multiple and Variable Binding of Pharmacologically Active Bis(maltolato)oxidovanadium(IV) to Lysozyme

The interaction with proteins of metal-based drugs plays a crucial role in their transport, mechanism, and activity. For an active ML_n complex, where L is the organic carrier, various binding modes (covalent and non-covalent, single or multiple) may occur and several metal moieties (M, ML, ML₂, etc.) may interact with proteins. In this study, we have evaluated the interaction of [V^IVO(malt)₂] (bis(maltolato)oxidovanadium(IV) or BMOV, where malt = maltolato, i.e., the common name for 3-hydroxy-2-methyl-4H-pyran-4-onato) with the model protein hen egg white lysozyme (HEWL) by electrospray ionization mass spectrometry, electron paramagnetic resonance, and X-ray crystallography. The multiple binding of different V-containing isomers and enantiomers to different sites of HEWL is observed. The data indicate both non-covalent binding of cis-[VO(malt)₂(H₂O)] and [VO(malt)(H₂O)₃]⁺ and covalent binding of [VO(H₂O)_3–4]²⁺ and cis-[VO(malt)₂] and other V-containing fragments to the side chains of Glu35, Asp48, Asn65, Asp87, and Asp119 and to the C-terminal carboxylate. Our results suggest that the multiple and variable interactions of potential V^IVOL₂ drugs with proteins can help to better understand their solution chemistry and contribute to define the molecular basis of the mechanism of action of these intriguing molecules.

The interaction of [V^IVO(malt)₂] (BMOV, malt = maltolato) with hen egg white lysozyme (HEWL) reveals the multiple binding of different V-containing isomers and enantiomers to different sites and non-covalent and covalent binding of cis-[VO(malt)₂(H₂O)], [VO(malt)(H₂O)₃]⁺, [VO(H₂O)₃₋₄]²⁺, and cis-[VO(malt)₂] to Glu, Asp, and Asn residues.

Oxoperoxovanadium Complexes of Hetero Ligands: X-Ray Crystal Structure, Density Functional Theory, and Investigations on DNA/BSA Interactions, Cytotoxic, and Molecular Docking Studies

Oxoperoxovanadium (V) complexes [VO (O)₂ (nf) (bp)] (1) and [VO (O)₂ (ox) (bp)] (2) based on 5-nitro-2-furoic acid (nf), oxine (ox) and 2, 2′ bipyridine (bp) bidentate ligands have been synthesized and characterized by FT-IR, UV-visible, mass, and NMR spectroscopic techniques. The structure of complex 2 shows distorted pentagonal-bipyramidal geometry, as confirmed by a single-crystal XRD diffraction study. The interactions of complexes with bovine serum albumin (BSA) and calf thymus DNA (CT-DNA) are investigated using UV-visible and fluorescence spectroscopic techniques. It has been observed that CT-DNA interacts with complexes through groove binding mode and the binding constants for complexes 1 and 2 are 8.7 × 10³ M⁻¹ and 8.6 × 10³ M⁻¹, respectively, and BSA quenching constants for complexes 1 and 2 are 0.0628 × 10⁶ M⁻¹ and 0.0163 × 10⁶ M⁻¹, respectively. The ability of complexes to cleave DNA is investigated using the gel electrophoresis method with pBR322 plasmid DNA. Furthermore, the cytotoxic effect of the complexes is evaluated against the HeLa cell line using an MTT assay. The complexes are subjected to density functional theory calculations to gain insight into their molecular geometries and are in accordance with the results of docking studies. Furthermore, based on molecular docking studies, the intermolecular interactions responsible for the stronger binding affinities between metal complexes and DNA are discussed.

Relationship between structure and cytotoxicity of vanadium and molybdenum complexes with pyridoxal derived ligands

In this work four vanadium complexes (compounds 1, 2, 3 and 4) and one molybdenum complex (compound 5) with hydrazone ligands derived from pyridoxal were synthesized and characterized. All compounds are mononuclear species, two of them (compounds 3 and 5) are dioxide complexes and the other three (compounds 1, 2 and 4) monoxide complexes. The vanadium atom of the compound 3 is five-coordinated and all the other compounds have a six coordinated environment polyhedron. The poses for the potential intercalation of the compounds 2 and 3 with DNA were obtained by using AutoDock software. Optimizations were also performed at PM6-D3H4 semi-empirical level whereas the study of the nature of the interaction was carried out by means of the Energy Decomposition Analysis and the Non-Covalent Interaction index by using in both cases Density Functional Theory computations. The cytotoxicity in lung cancer cells (A549 cell line) of all the compounds was also evaluated. After 24 h of treatment, vanadium complexes showed high values of IC₅₀, between 419.93 ± 22.58 and 685.88 ± 46.55 μM. After 48 h, the results showed that the compound 3 had the lowest IC₅₀ value, 65.32 ± 9.95 μM, and the compound 2 the highest value, 375.28 ± 32.09 μM. The molybdenum complex showed the lowest IC₅₀ value at 48 h (11.22 ± 1.34 μM). The toxicity of the compounds 3, 4 and 5 was tested in vivo, using zebrafish model, and the molybdenum complex showed higher toxic effects than the studied vanadium complexes.

An Adequate Supply of Bis(ethylmaltolato)oxidovanadium(IV) Remarkably Reversed the Pathological Hallmarks of Alzheimer's Disease in Triple-Transgenic Middle-Aged Mice

Alzheimer's disease (AD) is a complex and progressive neurodegenerative disease with impaired synapse, imbalanced mineral metabolism, protein mis-folding and aggregation. Bis(ethylmaltolato)oxidovanadium(IV) (BEOV), an organic bioactive vanadium compound with low toxicity and high bioavailability, has been studied as therapeutic agent against tuberculosis and diabetes. However, its neuroprotective effects have rarely been reported. Therefore, in this study, the potential application of BEOV in intervening AD cognitive dysfunction and neuropathology was evaluated. Both low- and high-dose of BEOV (0.2 mmol/L and 1.0 mmol/L) supplementation for 2 months improved the spatial learning and memory deficits of the triple-transgenic AD (3 × Tg AD) mice and mitigated the loss of synaptic proteins and synaptic dysfunction. By inhibiting the expression of amyloid-β precursor protein and β-secretase, and the phosphorylation of tau protein at Ser262, Ser396, Ser404, and Ser202/Thr205 residues, BEOV reduced the amyloid-β deposition and neurofibrillary tangle formation in AD mouse brains and primarily cultured neurons. Further analysis of the brain ionome revealed that BEOV supplementation could significantly affect the concentrations of a variety of metals, most of which, including several AD risk metals, showed reduced levels, particularly with a high-dose intake. Additionally, the elemental correlation network identified both conserved and specific elemental correlations, implying a highly complex and dynamic crosstalk between vanadium and other elements during long-term BEOV supplementation. Overall, our results suggest that BEOV is effective in AD intervention via both ameliorating the disease related pathology and regulating metal homeostasis.

Diastereomeric Separation of Chiral fac-Tricarbonyl(iminopyridine) Rhenium(I) Complexes and Their Cytotoxicity Studies: Approach toward an Action Mechanism against Glioblastoma

A series of new (tricarbonyl)rhenium(I) complexes were synthesized using chiral bidentate ligands (+)/(-)-iminopyridines (L_R/L_S). The reaction yielded a mixture of mononuclear Re(I) diastereoisomers, formulated as fac-[Br(CO)₃Re_(S/R)L_(S/R)]. Each single diastereoisomer was isolated and fully characterized. X-ray crystallography and circular dichroism spectra verified their enantiomeric nature. The cytotoxicity of each complex was evaluated against six cancer cell lines. The effect of the two complexes on viability, proliferation, and migration was analyzed on glioblastoma cell lines (U251 and LN229). Changes in the expression of histones, apoptotic, and key signaling proteins, as well as alterations in DNA structure, were also observed. These experiments showed that the chirality associated with both metal and ligand has a strong influence on cytotoxicity.

Dependency of EGFR activation in vanadium-based sensitization to oncolytic virotherapy

Oncolytic virotherapy is a clinically validated approach to treat cancers such as melanoma; however, tumor resistance to virus makes its efficacy variable. Compounds such as sodium orthovanadate (vanadate) can overcome viral resistance and synergize with RNA-based oncolytic viruses. In this study, we explored the basis of vanadate mode of action and identified key cellular components in vanadate’s oncolytic virus-enhancing mechanism using a high-throughput kinase inhibitor screen. We found that several kinase inhibitors affecting signaling downstream of the epidermal growth factor receptor (EGFR) pathway abrogated the oncolytic virus-enhancing effects of vanadate. EGFR pathway inhibitors such as gefitinib negated vanadate-associated changes in the phosphorylation and localization of STAT1/2 as well as NF-κB signaling. Moreover, gefitinib treatment could abrogate the viral sensitizing response of vanadium compounds in vivo. Together, we demonstrate that EGFR signaling plays an integral role in vanadium viral sensitization and that pharmacological EGFR blockade can counteract vanadium/oncolytic virus combination therapy.

Effect of Bis(maltolato)oxovanadium(IV) on Zinc, Copper, and Manganese Homeostasis and DMT1 mRNA Expression in Streptozotocin-Induced Hyperglycemic Rats

Our aim was to examine whether vanadium (IV) corrects alterations in zinc, copper and manganese homeostasis, observed in streptozotocin-induced hyperglycemic rats, and whether such changes are related to divalent metal transporter 1 (DMT1) mRNA expression, and antioxidant and proinflammatory parameters. Four groups of Wistar rats were examined: control; hyperglycemic (H); hyperglycemic treated with 1 mg V/day (HV); and hyperglycemic treated with 3 mg V/day (HVH). Vanadium was supplied in drinking water as bis(maltolato)oxovanadium(IV) for five weeks. Zinc, copper and manganese were measured in food, excreta, serum and tissues. DMT1 mRNA expression was quantified in the liver. Hyperglycemic rats showed increased Zn and Cu absorption and content in the liver, serum, kidneys and femurs; DMT1 expression also increased (p < 0.05 in all cases). HV rats showed no changes compared to H rats other than decreased DMT1 expression (p < 0.05). In the HVH group, decreased absorption and tissular content of studied elements (p < 0.05 in all cases) and DMT1 expression compared to H (p < 0.05) were observed. Liver zinc, copper and manganese content correlated positively with glutathione peroxidase activity and negatively with catalase activity (p < 0.05 in both cases). In conclusion, treatment with 3 mg V/d reverted the alterations in zinc and copper homeostasis caused by hyperglycemia, possibly facilitated by decreased DMT1 expression.

Vanadium and diabetic dyslipidemia: A systematic review of animal studies

BACKGROUND

Diabetic dyslipidemia is caused by hyperglycemia and excessive mobilization of storage lipids, leading to increasing concentrations of triglycerides and total cholesterol. Due to the insulin-mimetic or insulin-enhancer features of vanadium, it has been recognized as a regulator of cell metabolism with hypoglycemic and hypolipidemic properties. The purpose of the current animal systematic review was to evaluate the effect of vanadium administration on diabetic dyslipidemia in diabetic animals.

METHODS

This is, to our knowledge, the first systematic review with the aim of investigating the relationship between vanadium and diabetic dyslipidemia among diabetes induced animals. Searches were performed in PubMed, Scopus, and web of science databases for animal studies examining the effect of vanadium on diabetic dyslipidemia in diabetic animals.

RESULTS

Of 124 full-text articles assessed, 48 animal studies were included in the present study with minor risk of bias. The majority of the studies confirmed the beneficial effects of different vanadium compounds in at least one of the parameters of lipid profile, especially regarding triglyceride and total cholesterol.

CONCLUSION

Current findings lend support to assess the long-term effects of different forms and doses of vanadium on lipid profile through well-designed clinical trials.

Mono Versus Dinuclear Vanadium(V) Complexes: Solvent Dependent Structural Versatility and Electro Syntheses of Mixed-Valence Oxovanadium(IV/V) Entities in Solution

Two mononuclear oxidovanadium(V) complexes type of [V^VO(L¹)(OMe)(MeOH)] (1), [V^VO(L²)(OMe)(MeOH)] (2) and two [V₂O₃]⁴⁺ core of μ-oxidodioxidodivanadium(V) complexes (L¹)(O)V^V-O-V^V(O)(L¹) (3) and (L²)(O)V^V-O-V^V(O)(L²) (4) and two complexes [V^VO(L¹)(8-Hq)] (5) and [V^VO(L²)(8-Hq)] (6) incorporating 8-hydroxyquinoline (8-hq) as co-ligand have been reported where L¹ [(E)-N'-(2-hydroxybenzylidene)cinnamohydrazide] and L² [(2E,N'E)-N'-(2-hydroxybenzylidene)-3-(naphthalen-1-yl)acrylohydrazide] are the dianionic forms of the conjugated keto-imine functionalized substituted hydrazone ligands. The μ-oxidodioxidodivanadium complexes are generated upon switching the solvent from methanol to acetonitrile. The X-ray analysis showed octahedral geometry for the mononuclear complexes 1, 2 and 5 but oxido-bridged dinuclear complexes 3 and 4 formed penta-coordinated square-pyramidal geometry about metal atoms. Two mixed-valence species of type II, 3a and 4a, of general formulae (L)(O)V^IV-O-V^V(O)(L), are being generated upon constant potential electrolysis (CPE) of 3 and 4 respectively. Frozen solution EPR spectra have 13 hyperfine lines, revealing the unpaired electron is majorly localized on one of the two vanadium centres. All these complexes have been well characterized by physio-chemical techniques and the density functional theory (DFT) calculations were applied to obtain further insight into the electronic structure of this type of molecule. The oxidomethoxido complexes 1 and 2 were taken to investigate the catechol oxidase mimicking activity following the oxidation of 3,5-di-tert-butyl catechol (3,5-DTBC) to 3,5-di-tert-butyl benzoquinone (3,5-DTBQ).

Advantageous Reactivity of Unstable Metal Complexes: Potential Applications of Metal-Based Anticancer Drugs for Intratumoral Injections

Injections of highly cytotoxic or immunomodulating drugs directly into the inoperable tumor is a procedure that is increasingly applied in the clinic and uses established Pt-based drugs. It is advantageous for less stable anticancer metal complexes that fail administration by the standard intravenous route. Such hydrophobic metal-containing complexes are rapidly taken up into cancer cells and cause cell death, while the release of their relatively non-toxic decomposition products into the blood has low systemic toxicity and, in some cases, may even be beneficial. This concept was recently proposed for V(V) complexes with hydrophobic organic ligands, but it can potentially be applied to other metal complexes, such as Ti(IV), Ga(III) and Ru(III) complexes, some of which were previously unsuccessful in human clinical trials when administered via intravenous injections. The potential beneficial effects include antidiabetic, neuroprotective and tissue-regenerating activities for V(V/IV); antimicrobial activities for Ga(III); and antimetastatic and potentially immunogenic activities for Ru(III). Utilizing organic ligands with limited stability under biological conditions, such as Schiff bases, further enhances the tuning of the reactivities of the metal complexes under the conditions of intratumoral injections. However, nanocarrier formulations are likely to be required for the delivery of unstable metal complexes into the tumor.

Vanadyl sulphate ameliorates biomarkers of endothelial injury and coagulation and thrombosis in a rat model of hyperglycaemia

BACKGROUND

We sought to determine whether the insulin mimicking agent, vanadyl sulphate (Van) can inhibit biomarkers of endothelial injury and coagulation and thrombosis induced by a moderate level of hyperglycaemia.

MATERIAL AND METHODS

Hyperglycaemia was induced in rats by a single injection of streptozotocin (STZ, 50 mg/kg) two weeks after being fed on a high-fat diet (model group). The treatment group started Van (20 mg/kg/day) treatment one-week post STZ injection and continued on Van until being sacrificed at week 10.

RESULTS

Administration of Van to the model group significantly (p < .05) ameliorated dyslipidemia and biomarkers of inflammation (TNF-α, IL-6, and hsCRP) and endothelial injury (E-selectin, P-selectin, sICAM-1, sVCAM-1, and ET-1). Van also significantly inhibited hyperglycaemia-induced blood levels of coagulation (vWF) and thrombosis (PAI-1 and fibrinogen) biomarkers.

CONCLUSIONS

Vanadyl sulphate effectively suppresses hyperglycaemia-induced endothelial injury, coagulation and thrombosis, which is associated with the inhibition of inflammation and dyslipidemia.

A Multi-Technique Investigation of the Complex Formation Equilibria between Bis-Deferiprone Derivatives and Oxidovanadium (IV)

The increasing biomedical interest in high-stability oxidovanadium(IV) complexes with hydroxypyridinone ligands leads us to investigate the complex formation equilibria of V^IVO²⁺ ion with a tetradentate ligand, named KC21, which contains two 3-hydroxy-1,2-dimethylpyridin-4(1H)-one (deferiprone) moieties, and with the simple bidentate ligand that constitutes the basic unit of KC21, for comparison, named L5. These equilibrium studies were conducted with joined potentiometric–spectrophotometric titrations, and the results were substantiated with EPR measurements at variable pH values. This multi-technique study gave evidence of the formation of an extremely stable 1:1 complex between KC21 and oxidovanadium(IV) at a physiological pH, which could find promising pharmacological applications.

What are the prospects for using complexes of copper(ii) and zinc(ii) to suppress the vital activity of Mycolicibacterium smegmatis?

New complexes of zinc(ii) and copper(ii) with 2-furoic acid (Hfur), acetic acids and N-donor ligands with the compositions [Zn₂(fur)₄]_n (1), [Zn₂(fur)₄(NH₂py)₂] (2, NH₂py = 3-aminopyridine), [Zn(fur)₂(neoc)] (3, neoc = 2,9-dimethyl-1,10-phenantroline), [Zn(OAc)₂(neoc)] (4, OAc = acetat-anion), and [Cu(fur)₂(neoc)(H₂O)] (5) were synthesized. The structures of the compounds were established by single crystal X-ray diffraction analysis. Complexes 1 and 2 are binuclear; whereas 3–5 are mononuclear. The stabilization of supramolecular architectures in crystals for compounds 1–5 occurs due to π–π-bonding between heterocycles and hydrogen interactions that provide good solubility in aqueous solutions. The stability of the complexes upon dissolution in 5% dextrose and 0.9% NaCl was confirmed by UV-vis spectroscopic and NMR (¹H) data. The study of in vitro biological activity was carried out against the non-pathogenic strain of Mycolicibacterium smegmatis that is a model for M. tuberculosis. The synergistic effect of ligands is observed for complexes 3–5 and is characterized by an increase in the biological activity values. On passage from Zn²⁺ to Cu²⁺ complexes, the biological activity increases and the maximum effect is observed for compound [Cu(fur)₂(phen)]. Analysis of the transcriptomic profiles of the M. smegmatis mc²155 strain under the pressure of the copper complex [Cu(fur)₂(phen)] made it possible to isolate 185 genes, one quarter of which are associated with the compensation of iron deficiency in the bacterial strain. Genes associated with the transport and metabolism of heavy metals, biosynthesis of fatty and amino acids, biodegradation and transport of urea were also isolated.

New complexes of zinc(ii) and copper(ii) with 2-furoic acid (Hfur), acetic acids and N-donor ligands with the compositions [Zn₂(fur)₄]_n, [Zn₂(fur)₄(NH₂py)₂], [Zn(fur)₂(neoc)], [Zn(OAc)₂(neoc)], and [Cu(fur)₂(neoc)(H₂O)] were synthesized.

Targeting Breast Cancer and Their Stem Cell Population through AMPK Activation: Novel Insights

Despite some significant advancements, breast cancer has become the most prevalent cancer in the world. One of the main reasons for failure in treatment and metastasis has been attributed to the presence of cancer initiating cells—cancer stem cells. Consequently, research is now being focussed on targeting cancer cells along with their stem cell population. Non-oncology drugs are gaining increasing attention for their potent anticancer activities. Metformin, a drug commonly used to treat type 2 diabetes, is the best example in this regard. It exerts its therapeutic action by activating 5′ adenosine monophosphate-activated protein kinase (AMPK). Activated AMPK subsequently phosphorylates and targets several cellular pathways involved in cell growth and proliferation and the maintenance of stem-like properties of cancer stem cells. Therefore, AMPK is emerging as a target of choice for developing effective anticancer drugs. Vanadium compounds are well-known PTP inhibitors and AMPK activators. They find extensive applications in treatment of diabetes and obesity via PTP1B inhibition and AMPK-mediated inhibition of adipogenesis. However, their role in targeting cancer stem cells has not been explored yet. This review is an attempt to establish the applications of insulin mimetic vanadium compounds for the treatment of breast cancer by AMPK activation and PTP1B inhibition pathways.

The effects of a new antidiabetic glycinium [(pyridine-2, 6-dicarboxylato) oxovanadate (V)] complex in high-fat diet of streptozotocin-induced diabetic rats

OBJECTIVE

The present study aimed to evaluate the antidiabetic effects of glycinium [(pyridine-2, 6-dicarboxylato) oxovanadate (V)] complex in type 2 diabetes rat model.

MATERIALS AND METHODS

Rats were allocated into 6 groups. Group I, nondiabetic rats; Group II, diabetic rats; Group III, diabetic rats receiving an intraperitoneal (i.p.) injection of metformin (45 mg/kg); Groups IV, V and VI were diabetic rats receiving i.p. injection of 5, 10, and 20 mg/kg of the complex for 3 weeks, respectively. Fasting blood glucose (FBG), insulin, liver enzymes, malondialdehyde (MDA), total antioxidant capacity (TAC), lipid profile, and HbA1c were measured.

RESULTS

AST, ALT and GGT activities and MDA levels were increased, while TAC was decreased in diabetic animals. Treatment of diabetic rats improved the HOMA-IR and returned HbA1c level to the normal value as well as elevated TAC and reduced MDA level.

CONCLUSION

We found that the complex possesses antidiabetic properties in experimental diabetes.

Efficacy of Vanadyl Sulfate and Selenium Tetrachloride as Anti-Diabetic Agents against Hyperglycemia and Oxidative Stress Induced by Diabetes Mellitus in Male Rats

The use of metals in medicine has grown in popularity in clinical and commercial settings. In this study, the immune-protecting effects and the hypoglycemic and antioxidant activity of vanadyl sulfate (VOSO₄) and/or selenium tetrachloride (Se) on oxidative injury, DNA damage, insulin resistance, and hyperglycemia were assessed. Fifty male albino rats were divided into five groups, and all treatments were administrated at 9:00 a.m. daily for 60 successive days: control, STZ (Streptozotocin; 50 mg/kg of STZ was given to 6 h fasted animals in a single dose, followed by confirmation of diabetic state occurrence after 72 h by blood glucose estimation at >280 mg/dl), STZ (Diabetic) plus administration of VOSO₄ (15 mg/kg) for 60 days, STZ (Diabetic) plus administration of selenium tetrachloride (0.87 mg/Kg), and STZ plus VOSO₄ and, after 1/2 h, administration of selenium tetrachloride at the above doses. The test subjects’ blood glucose, insulin hormone, HbA1C, C-peptide, antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, myeloperoxidase, and xanthine oxidase), markers of lipid peroxidation (MDA), and histological sections of pancreatic tissues were evaluated, and a comet assay was performed. Histological sections in pancreas tissues were treated as indicators of both VOSO₄ and selenium tetrachloride efficacy, either alone or combined, for the alleviation of STZ toxicity. The genotoxicity of diabetes mellitus was assessed, and the possible therapeutic roles of VOSO₄ or selenium tetrachloride, or both, on antioxidant enzymes were studied. The findings show that the administration of VOSO₄ with selenium tetrachloride reduced oxidative stress to normal levels, lowered blood glucose levels, and elevated insulin hormone. Additionally, VOSO₄ with selenium tetrachloride had a synergistic effect and significantly decreased pancreatic genotoxicity. The data clearly show that both VOSO₄ and selenium tetrachloride inhibit pancreatic and DNA injury and improve the oxidative state in male rats, suggesting that the use of VOSO₄ with selenium tetrachloride is a promising synergistic potential ameliorative agent in the diabetic animal model.

Spectroscopic/Computational Characterization and the X-ray Structure of the Adduct of the VIVO-Picolinato Complex with RNase A

The structure, stability, and enzymatic activity of the adduct formed upon the reaction of the V-picolinato (pic) complex [VIVO(pic)2(H2O)], with an octahedral geometry and the water ligand in cis to the V═O group, with the bovine pancreatic ribonuclease (RNase A) were studied. While electrospray ionization-mass spectrometry, circular dichroism, and ultraviolet-visible absorption spectroscopy substantiate the interaction between the metal moiety and RNase A, electron paramagnetic resonance (EPR) allows us to determine that a carboxylate group, stemming from Asp or Glu residues, and imidazole nitrogen from His residues are involved in the V binding at acidic and physiological pH, respectively. Crystallographic data demonstrate that the VIVO(pic)2 moiety coordinates the side chain of Glu111 of RNase A, by substituting the equatorial water molecule at acidic pH. Computational methods confirm that Glu111 is the most affine residue and interacts favorably with the OC-6-23-Δ enantiomer establishing an extended network of hydrogen bonds and van der Waals stabilizations. By increasing the pH around neutrality, with the deprotonation of histidine side chains, the binding of the V complex to His105 and His119 could occur, with that to His105 which should be preferred when compared to that to the catalytically important His119. The binding of the V compound affects the enzymatic activity of RNase A, but it does not alter its overall structure and stability.

Influence of temperature on the equilibria of oxidovanadium(IV) complexes in solution

The equilibria in the solution of three different oxidovanadium(IV) complexes, VO(dhp)₂ (dhp = 1,2-dimethyl-3-hydroxy-4(1H)-pyridinonato), VO(ma)₂ (ma = maltolato) and VO(pic)₂(H₂O) (pic = picolinato), were examined in the temperature range of 120-352 K through a combination of instrumental (EPR spectroscopy) and computational techniques (DFT methods). The results revealed that a general equilibrium exists: VOL₂ + H₂O ⇄ cis-VOL₂(H₂O) ⇄ trans-VOL₂(H₂O), where cis and trans refer to the relative position of H₂O and the oxido ligand. The equilibrium is more or less shifted to the right depending on the ligand, the temperature, the ionic strength and the coordinating properties of the solvent. With VO(dhp)₂, only the square pyramidal species exists at 298 K in aqueous solution, while at 120 K the cis- and trans-VO(dhp)₂(H₂O) species are also present. The complex of maltol exists almost exclusively in the form cis-VO(ma)₂(H₂O) in aqueous solution at 298 K, while the trans species can be revealed only at higher temperatures, where the EPR linewidth significantly decreases. The equilibria involving 1-methylimidazole (MeIm), a model for the side chain His coordination, are also influenced by temperature, with its coordination being favored by decreasing the temperature. The implications of these results in the study of the (vanadium complex)-protein systems are discussed and the interaction with myoglobin (Mb) is examined as a representative example.

Alzheimer's Disease and Diabetes Mellitus in Comparison: The Therapeutic Efficacy of the Vanadium Compound

Alzheimer’s disease (AD) is an intractable neurodegenerative disease that leads to dementia, primarily in elderly people. The neurotoxicity of amyloid-beta (Aβ) and tau protein has been demonstrated over the last two decades. In line with these findings, several etiological hypotheses of AD have been proposed, including the amyloid cascade hypothesis, the oxidative stress hypothesis, the inflammatory hypothesis, the cholinergic hypothesis, et al. In the meantime, great efforts had been made in developing effective drugs for AD. However, the clinical efficacy of the drugs that were approved by the US Food and Drug Association (FDA) to date were determined only mild/moderate. We recently adopted a vanadium compound bis(ethylmaltolato)-oxidovanadium (IV) (BEOV), which was originally used for curing diabetes mellitus (DM), to treat AD in a mouse model. It was shown that BEOV effectively reduced the Aβ level, ameliorated the inflammation in brains of the AD mice, and improved the spatial learning and memory activities of the AD mice. These finding encouraged us to further examine the mechanisms underlying the therapeutic effects of BEOV in AD. In this review, we summarized the achievement of vanadium compounds in medical studies and investigated the prospect of BEOV in AD and DM treatment.