The antiproliferative activity of all the synthesized compounds was evaluated against the human estrogen-responsive MCF-7 breast cancer cell line and ERα-negative MDA-MB231 cells using the MTT assay (Figures S1, S2). Cisplatin, a standard chemotherapy drug, was used as the reference compound. All compounds were also tested for cytotoxicity toward prostate cancer cells (Figures S3, S4). AR-negative PC3 cells and AR-positive 22Rv1 cells were used in this assay. The corresponding inhibitory concentrations IC50 (IC50 is the half maximal inhibitory concentration) are given in Table 1.