Vanadium(V) complexes with salicylaldehyde semicarbazone derivatives bearing in vitro anti-tumor activity toward kidney tumor cells (TK-10): crystal structure of [V VO 2(5-bromosalicylaldehyde semicarbazone)

Abstract

As a contribution to the development of novel vanadium complexes with pharmacologically interesting moieties, new dioxovanadium(V) semicarbazone complexes with the formula cis-VO 2L, where L = 5-bromosalicylaldehyde semicarbazone and 2-hydroxynaphtalen-1-carboxaldehyde semicarbazone have been synthesized and characterized by 1H and 13C NMR, Raman and FTIR spectroscopies. Results were compared with those previously reported for other three analogous complexes of this series. The five complexes were tested in three different human tumor cell lines for bioactivity as potential anti-tumor agents, showing selective cytotoxicity on TK-10 cell line. Results showed that structural modifications on the semicarbazone moiety could have a significant effect on the anti-tumor activity of the vanadium complexes. In addition, the electrochemical behavior of all the complexes was studied. No apparent correlation could be demonstrated between reduction potentials of the complexes and their anti-tumor activities. The molecular structure of the novel [V VO 2(5-bromosalicylaldehyde semicarbazone)] complex was solved by X-ray diffraction methods. The vanadium atom shows a distorted square pyramidal coordination sphere. The (VO 2) + cation is coordinated to a nearly planar (L) − anion acting as a tridentate ligand through both oxygen and one nitrogen atoms.