Polyoxoanions are cytotoxic to malignant glioma cells

We studied the cytotoxicity of five polyoxoanions on two human malignant glioma cell lines (T98G and 86HG39), a rat glioma cell line (C6) and a human fibroblast cell line (NIH-3T3) using MTT tests to measure the drug concentration killing 50% of the cells (LC50). Cisplatin was used as a reference agent. Cisplatin had the highest efficacy in three of the four cell lines. Only in T98G cells, one of the components (POA5) had a lower LC50 value (1.3 x 10(-6) mol/l) than cisplatin (2.5 x 10(-6)). POA5 was also the most cytotoxic polyoxoanion when the LC50 values of all four cell lines were averaged (6.6 x10(-6)). Average LC50 values of the other compounds were 10.9, 12.6, 19.0 and 19.2 x 10(-6) mol/l in POA1, POA2, POA3 and POA4, respectively. When the benign fibroblasts were used to calculate a therapeutic index as LC50 in fibroblasts divided by LC50 in glioma cells, POA5 was superior to cisplatin. These results indicate that polyoxoanions are cytotoxic for malignant glioma cells and that the most promising compound investigated here was POA5.