DNA-binding properties and cytotoxicity of extended aromatic bisamidines in breast cancer MCF-7 cells.

The DNA binding properties of three novel extended aromatic bisamidines (1-3) possessing different dicationic terminal side chains were studied. Data from the ethidium displacement assay showed that bisamidines 1-3 have significant affinity for DNA. We studied the cytotoxic activity of bisamidines 1-3 and Hoechst 33258 in the cultured breast cancer MCF-7 cells. These data show that in broad terms the cytotoxic potency of bisamidines 1-3 in the cultured breast cancer MCF-7 cells decreases with the size of the alkyl group substituent (cyclopropyl > isopropyl > cyclopentyl), in accord with their increases in DNA affinity, as shown by the binding constant values. The bisamidines 1-3 showed comparable antitumor activity to Hoechst 33258.