Synthesis, spectroscopic study and anticancer activity of a water-soluble Nb(V) peroxo complex

We synthesized, characterized and studied the anticancer properties of a new water-soluble peroxo niobium complex (K₃Nb(Asc)(O₂)₃]·4H₂O (Asc = ascorbate anion C₆H₆O₆²⁻))_, as well as that of ascorbic acid, in human leukemic cells. The complex was synthesized and characterized by elemental, IR, Raman, thermogravimetric analysis, detailed NMR and mass spectra analysis. The cytotoxic activity of the complex on HL-60 and K562 human leukemia cell lines has been investigated by assessing vital cellular mechanisms, such as the metabolic activity (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; MTT) and the proliferation capacity (growth curves) of leukemia cells, as well as the structural integrity of cell membrane (trypan blue assay). The complex exerts an increased antiproliferative effect primarily on HL60 human leukemia cells, compared to ascorbic acid alone, as well as an inhibitory effect on necrosis caused by ascorbic acid. Its effect on K562 cells concerns mainly its inhibitory effect upon cell necrosis induced by ascorbic acid alone. Our results support a concentration- and time-dependent enhanced antileukemic effect of the complex, suggesting its significance as a promising tool in the confrontation of leukemia.