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.

Synthesis, crystal structure, DFT calculations, protein interaction, anticancer potential and bromoperoxidase mimicking activity of oxidoalkoxidovanadium(v) complexes

Intriguing structure–activity relationships (SARs) indicating an apparent dependence of anticancer and haloperoxidase activities on the carbon chain length of the alkoxo group.

Syntheses, crystal structures, DFT calculations, protein interaction and anticancer activities of water soluble dipicolinic acid-imidazole based oxidovanadium(iv) complexes

Three novel water soluble neutral mononuclear oxidovanadium(iv) complexes 1-3, [VOLB₂] (where H₂L = dipicolinic acid (DPA) and B = imidazole (1)/1-methylimidazole (2)/1-allylimidazole (3)), were synthesized by the reaction of [VOL(H₂O)₂] with imidazole/1-methylimidazole/1-allylimidazole in ethanol. The complexes were thoroughly characterized by elemental analysis, IR, UV-Vis and EPR spectroscopy, magnetic susceptibility, cyclic voltammetry and single crystal X-ray diffraction techniques. In all the complexes the vanadium(iv) centre assumes a distorted octahedral environment. All the three complexes have similar structures and contain a range of intramolecular interactions such as hydrogen bonding, C-Hπ, and ππ stacking dominating their supramolecular architectures. A thermal study of the complexes was carried out to analyze their stability. The energy of non-covalent interactions and frontier orbitals for the complexes were also calculated by DFT. In order to investigate the binding interactions and conformational changes of the secondary structure of bovine serum albumin (BSA) with the complexes, absorption, fluorimetric titration and circular dichroism measurements in aqueous medium were carried out. Molecular docking studies have also been carried out to understand the binding modes and interaction patterns of the oxidovanadium(iv) complexes with BSA. The anticancer activities of the ligand and complexes 1-3 were tested against the human hepatic carcinoma cell line Hep3B. The complexes showed prominent cytotoxicity towards cancer cells.

Solid state π–π stacking and higher order dimensional crystal packing, reactivity, and electrochemical behaviour of salphenazine actinide and transition metal complexes

Here, we describe and compare the synthesis, solution characterization, and solid-state behaviour of the salphenazine ligand and metal complexes.

Hypoglycemic, lipid-lowering and metabolic regulation activities of metforminium decavanadate (H2Metf)3 [V10O28]·8H2O using hypercaloric-induced carbohydrate and lipid deregulation in Wistar rats as biological model

Because of the increasing global spread of type 2 diabetes mellitus, there is a need to develop new antidiabetic agents. Recently we have synthesized new decavanadates using metformin as counterion. In particular, the compound containing three metforminium dications has been obtained in high yield and has been completely characterized. Biological studies using Wistar rats that have been fed with a high caloric diet inducing insulin resistance and metabolic syndrome were carried out. Results of the impact on key biochemical parameters mediated by metformin alone and the new compound are here presented. The metforminium decavanadate (H2Metf)3[V10O28]·8H2O, abbreviated as Metf-V10O28, was shown to have pharmacological potential as a hypoglycemic, lipid-lowering and metabolic regulator, since the resulting compound made of the two components with antidiabetic activities, reduces both dosage and time of administration (twice a week). Hence, due to the beneficial effects induced by the metforminium decavanadate we recommend to continue the exploration into the mechanism and toxicology of this new compound.

Investigation of VO-salophen complexes electronic structure

Vanadyl N,N'-bis(salicylidene)-o-phenylenediamine (salophen) complexes have been extensively investigated by cyclic voltammetry, UV-visible spectroscopy and theoretical calculations in MeCN, THF (tetrahydrofuran) and DMF (N,N-dimethylformamide), in order to elucidate the overall factors that influence the electronic density of the metal and therefore the properties of these complexes in various applications. Different substituents were introduced into the salophen skeleton to change the vanadium electron density. Results obtained and here presented showed that the substituents influence the metal electronic character in a way that cannot be easily predicted by considering only the electronic effect. Similarly, the solvent polarity or coordination ability affects the metal complex properties in an unpredictable way. Therefore, experimental and theoretical data here collected are a powerful tool to a priori design salophen ligands to obtain vanadyl complexes having the specific electronic properties suitable for desired applications.

Donor atom electrochemical contribution to redox potentials of square pyramidal vanadyl complexes

A simple donor atom additivity relationship has been used to calculate the donor atom electrochemical contribution (DEC) of the Oac (acetylacetonate-enolic oxygen), OPh (phenolic oxygen), SPh (mercaptophenol sulfur), Nam (deprotonate amide nitrogen), Nim (imine nitrogen) and Npy (pyridine nitrogen) to the redox processes of the square pyramidal vanadyl complexes. The study focuses on the amidate vanadyl complexes because of (a) their biological interest and (b) the existence of data from plethora complexes studied in great details. The electrochemical contributions for the vanadyl oxidation and reduction processes increase following the same order, OPh~Oac(enolic)<SPh~Nam<Nim<Npy. These values predict the electrochemical potentials of square pyramidal vanadyl complexes with high accuracy. Octahedral complexes with the same equatorial environment show significant shift of the oxidation potentials to lower values. The DEC influence to the square pyramidal vanadyls' electrochemical potentials has been evaluated.