Enhanced antileukemic activity of the novel complex 2,5-dihydroxybenzoate molybdenum(VI) against 2,5-dihydroxybenzoate, polyoxometalate of Mo(VI), and tetraphenylphosphonium in the human HL-60 and K562 leukemic cell lines

We synthesized and studied the antitumor properties of the novel complex compound 2,5-dihydroxybenzoate molybdenum(VI) with tetraphenylphosphonium as counterion, which also acts as cancer cell growth inhibitor. A novel complex compound, the 2,5-dihydroxybenzoate molybdenum(VI) complex, (PPh4)(2)[Mo3O6(mu-O)(2)(2,5-DHBA)(2)] was synthesized. H-1 NMR, C-13 NMR, IR, and UV-Vis analyses were used for its molecular characterization. The human leukemia cell lines HL-60 and K562 were tested for their viability by assessing the metabolic activity of cells (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; MTT), the structural integrity of the cell membrane (Trypan blue assay), and cell proliferation ability (growth curves). We showed that both leukemia cell lines are induced to decreased proliferation efficiency after treatment with the novel complex, compared to 2,5-dihydroxybenzoate, tetraphenyl-phosphonium polyoxomolybdate, or tetraphenylphosphonium chloride as individual entities, in a time- and concentration-dependent manner. Our results suggest that the new 2,5-dihydroxybenzoate molybdenum(VI) complex may provide a valuable tool in cancer chemotherapy.