Vanadyl complexes with dansyl-labelled dipicolinic acid ligands: synthesis, phosphatase inhibition activity and cellular uptake studies

Vanadium complexes have been previously utilised as potent inhibitors of cysteine based phosphatases (CBPs). Herein, we present the synthesis and characterisation of two new fluorescently labelled vanadyl complexes (14 and 15) with bridged di-picolinic acid ligand. These compounds differ significantly from previous vanadyl complexes with phosphatase inhibition properties in that the metal-chelating part is a single tetradentate unit, which should afford greater stability and scope for synthetic elaboration then the earlier complexes. These new complexes inhibit a selection of cysteine based phosphatases (CBPs) in the nM range with some selectivity. Fluorescence spectroscopic studies (including fluorescence anisotropy) were carried out to demonstrate that the complexes are not simply acting as vanadyl delivery vehicles but they interact with the proteins. Finally, we present preliminary fluorescence microscopy studies to demonstrate that the complexes are cell permeable and localise throughout the cytoplasm of NIH3T3 cells

Studies on electrchemical reduction of Cd(II) complexes with alkyl thioureas

The formation of Cd(II) complexes with alkyl thioureas $(Tu=H_2NCSNH_2, CH_3Tu, C_2H_5Tu, C_4H_9Tu)$ has been studied in aqueous solution. Basing on CV and polarographic results the 2-electrons reversible mechanism was assigned. With the aid of POLAG (nonlinear least squares iterative program) the overall stability constants $(log \beta\ _n=1-4)$ were estimated. The values of LUMO energy, heat of formation and electrostatic potential minima were obtained on the basis of quantum-chemical calculations. They confirmed the ealier established stability sequence of Cd(II) complexes with alkyl thioureas, namely $Tu<CH_3Tu<C_2H_5Tu<C_4H_9Tu$. The estimation of $E _\frac {1}{2}$ for 1:1 and 1:4 complexes was made by linear regression

The impact of modifications of hesperetin molecule on its DNA interaction

Медицинская экология: биомедицина, генетика, эпидемиологическая и гигиеническая оценки среды обитания человекаSynthesis and characterization of Schiff base derived from hesperetin and 2-amonobenzhydrazide has been carried out. Structural elucidation of the Schiff base was analyzed based on various spectroscopic techniques (FTIR, electronic absorption spectra, NMR, FAB MS). The synthesized compound has been characterized based on analytical methods, elemental analysis, thermal, magnetic, and spectral studies (IR, UV-visible, 1H NMR, 13C NMR). The results of the mass spectroscopic data are consistent with the data of elementary analysis. Moreover, the structures of the hesperetin Schiff base were confirmed by potentiometric titration and spectroscopic method

Potentiometric, spectroscopic, electrochemical and DFT characterization of oxovanadium(IV) complexes formed by citrate and tartrates in aqueous solution at high ligand to metal molar ratios: the effects of the trigonal bipyramidal distortion in bis-chelated species and biological implications

The complexation of VO(IV) ion with citrate (L3−), D-, L- and DL-tartrate (L2−) at high ligand to metal molar ratios was studied in aqueous solution through the combined application of potentiometric, spectroscopic (UV-vis and EPR) and electrochemical (cyclic voltammetry) techniques. Unlike in equimolar solution, mononuclear and not dinuclear species are formed with the binding of carboxylate-COO− and alcoholate-O− donors yielding mono- and bis-chelated species with VOLH, VOL, VOLH−1 and VOL2H−2 composition; for tartrates also the “sugar-like” (O−, O−) coordination is involved in the vanadium binding at basic pH values giving rise to the formation of VOL2H−3 and VOL2H−4 complexes. Among the species formed, VOL2H−2 is characterised by a strong distortion towards the trigonal bipyramid with the two V–O(alcoholate) bonds in the equatorial and the two V–O(carboxylate) bonds in the axial positions. The geometry and electronic absorption spectra of such complexes were simulated by DFT methods and it was found that in aqueous solution the distortion follows the steric hindrance of the substituents on the α-carbon atom and the hydrophobicity of the ligands. The results were compared with those displayed by simple α-hydroxycarboxylates (glycolate, 2-hydroxyisobutyrate, 2-ethyl-2-hydroxybutyrate and benzilate). The trigonal bipyramidal distortion was correlated with the values of: i) Δλ = λ2 − λ3, where λ2 and λ3 are the central bands in the electronic absorption spectrum; ii) |Ax − Ay|, where Ax and Ay are the 51V hyperfine coupling constants along the x and y axes in the anisotropic EPR spectrum; iii) the half-wave potential E1/2 of oxidation of VO(IV) to the corresponding VO2(V) species in the cyclic voltammogram. Finally, a discussion on the possible form of VO(IV)–citrate complexes in blood serum is presented, where it is found that the most relevant species under physiological conditions should be [VO(citrH−1)]2−