Structures, physicochemical and cytoprotective properties of new oxidovanadium(IV) complexes -[VO(mIDA)(dmbipy)]•1.5H2O and [VO(IDA)(dmbipy)]•2H2O

New oxidovanadium(IV) complexes with a modification of the ligand in the VO+ coordination sphere were synthesized. [VO(mIDA)(dmbipy)]1.5H(2)O and [VO(IDA)(dmbipy)].2H(2)O were obtained as dark green crystals and grey-green powder, respectively (mIDA = N-methyliminodiacetic anion, IDA = iminodiacetic anion, dmbipy = 4,4'-dimethoxy-2,2'-dipyridyl). The crystal structure of [VO(mIDA)(dmbipy)].1.5H(2)O has been determined by the X-ray diffraction method. The studies of structure of [VO(mIDA)(dmbipy)].1.5H(2)O have shown that this compound occurs in the crystal as two rotational conformers. Furthermore, the stability constants of [VO(mIDA)(dmbipy)].1.5H(2)O and [VO(IDA)(dmbipy)].2H(2)O complexes in aqueous solutions were studied by using the potentiometric titration method and, consequently, determined using the Hyperquad2008 program. Moreover, the title complexes were investigated as antioxidant substances. The impact of the structure modification in the VO+ complexes on the radical scavenging activity has been studied. The ability to scavenge the superoxide radical by two complexes - [VO(mIDA)(dmbipy)].1.5H(2)O and [VO(IDA)(dmbipy)].2H(2)O was studied by cyclic voltammetry (CV) and nitrobluetetrazolium (NBT) methods. The title complexes were also examined by the spectrophotometric method as scavengers of neutral organic radical - 1,1-diphenyl-2-picrylhydrazyl (DPPH.) and radical cation - 2,2'-azinobis-(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS.(+)). Furthermore, the biological properties of two oxidovanadium(IV) complexes were investigated in relation to its cytoprotective properties by the MTT and LDH tests based on the hippocampal HT22 neuronal cell line during the oxidative damage induced by hydrogen peroxide. Finally, the results presented in this paper have shown that the both new oxidovanadium(IV) complexes with the 4,4'-dimethoxy-2,2'-dipyridyl ligand can be treated as the cytoprotective substances.