Effect of complex 1 and 2 and the associated ligands on U1 cell viability. A dose response curve was obtained for complexes 1 and 2 from 0.2-25 μM with CC50 values of 0.53 ± 0.12 and 1.00 ± 0.4 μM respectively. L1, L2 and HU were less toxic with CC50 > 100 μM while that of the gold (synthesis) starting material, HAuCl4.4H2O was >50 μM. The numbers above the bar graphs are the CC50 values. # Two fold serial dilutions from 100 down to 0.8 μM were performed. ****p < 0.0001, ***p = 0.0001, **p = 0.002.