Assemblies of salen-type oxidovanadium(iv) complexes: substituent effects and in vitro protein tyrosine phosphatase inhibition

Abstract

Oxidovanadium(IV) complexes with substituted chiral tetradentate dianionic N,N'-bis-o-hydroxybenzylidene-1,2-propylenediamines were synthesized and their physicochemical properties were characterized using single crystal X-ray diffraction, elemental analysis, ATR FTIR, UV-VIS and EPR spectroscopy, cyclic voltammetry, spectroelectrochemistry and preliminary in vitro protein-tyrosine phosphatase inhibition activity studies. Different 5-substituents in the salicylaldehyde (condensed with 1,2-diaminopropane; 2 : 1) were tested, namely 5-Br (complex 1), 5-Cl (2), 5-NO2 (3) and 5-OCH3 (4). The crystal structures of 1 and 2 show square pyramidal coordination of vanadium and parallel arrangement of monomeric exo isomers in supramolecular dimers. The halogen-halogen interaction of substituents in 5,5'-positions leads to weakening of axial interaction between phenolate O and V in 2, compared to 1. The Br atom takes part in halogen bonding with a vanadyl group in 1. Complex 3 has a linear polymeric structure with a V-O-V asymmetric bridge motif (IR absorption band at 873 cm(-1), separated d-d bands and broad EPR band structure in frozen solution pointing to oligomeric nature) while 4 is monomeric (V=O stretching at 976 cm(-1), broad d-d band structure). Redox potentials of the V(4+)/V(5+) couple lie in the range of -0.14 to 0.21 V (vs. Fc/Fc(+)) and show substantial dependence on the electron withdrawing properties of the substituents. The charge transfer character of the bands present in the range 365-395 nm was confirmed based on UV-VIS spectroelectrochemical experiments. Different assemblies of complex molecules are influenced by the electron withdrawing properties of the 5,5'-substituents, leading to supramolecular dimers (1, 2 and 4) and linear polymeric self-assembly (3). An in vitro study of representative complex 1 showed protein tyrosine phosphatase activity inhibition higher than that of suramin but lower than those of oxidovanadium(IV) sulphate and bis(maltolato)oxidovanadium(IV).

Potentiation of adipogenesis and insulinomimetic effects of novel vanadium complex (N'-[(E)-(5-bromo-2-oxophenyl)methylidene]-4-methoxybenzohydrazide)oxido(1,10-phenanthroline)vanadium(IV) in 3T3-L1 cells

“…After 10 minutes, a solution of phosphate 6,8-difluoro-4-methylumbelliferyl phosphate (DiFMUP) was added until its final concentration was 0.1 mM. After 20 minutes of incubation at room temperature, the fluorescence intensity (355 nm excitation and 560 nm emission) was measured on a multifunction plate reader (POLARstar Omega, BMG Labtech, Germany) [24,25]. Assays were conduct in triplicates.…”

The pharmacological/toxicological effects and rational drug design of vanadium complexes

“…啶 二 甲 酸 氧 钒 (VO-DPA) 、 吡 啶 甲 酸 酞 胺 氧 钒 (VO-PAM)、甲基吡啶甲酸氧钒(VO-MPA)、吡啶甲酸氧 钒(VO-PA) [93] 和5-碘-吡啶甲酸氧钒(VO(iPa)2) [94] , 考察 合物活性也有影响 [78,95] .…”

Tridentate hydrazido-hydrazones vanadium complexes. Synthesis, properties and biological activity

“…One of the significant role of vanadium was found recently as decreasing the resistance to oncolytic immunotherapy [8]. On the other hand, chemistry and properties of vanadium complexes with Schiff bases allowed us to study the possible coordination modes of vanadium, stability of its oxidation states, role of co-ligands and the stability in solution [9,10].…”