Cytotoxic effects of novel polyoxotungstates and a platinum compound on human cancer cell lines.

The cytotoxicity of a new platinum compound Pt1 [2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedichloroplatin(II)] and six polyoxometalates (POM1-6) on two neuroblastoma cell lines (SHEP-SF and KCN) and an Ewing's Sarcoma cell line (CADO-ES-1) was studied. Cisplatin [cis-diamminedichloroplatinum(II)] and carboplatin [cis-diammine(cyclobutanedicarboxylato)platinum(II)] were used as reference agents. Using MTT tests, the cytotoxicity (LD50: lethal doses 50%) of the compounds were measured at different concentrations. After 72 h exposure, the LD50 data for the platinum-containing substances ranged between 4.47 x 10(-6) and 1.91 x 10(-4) M. The SHEP-SF cell line displayed the highest sensitivity to cisplatin. The novel platinum agent Pt1 had a similar cytotoxic effect to the reference agent cisplatin. Both cisplatin and Pt1 were more cytotoxic than carboplatin. The POMs reduced cell viability compared to untreated cells at concentrations between 8.4 x 10(-7) and 3.47 x 10(-5) M. POM1 ([(CH3)4N]2Na6.5(NH4)2[SnII1.5(WO2(OH))0.5(WO2)2(SbW9O33)2] x 32H2O) was the most effective polyoxoanion with a mean LD50 value of 8.83 x 10(-6) M in the three cell lines tested. With CADO-ES-1 and KCN cells, POM1 was found to be more effective than the platinum compounds cisplatin, carboplatin and Pt1.