Novel Ametantrone-Amsacrine Related Hybrids as Topoisomerase II? Poisons and Cytotoxic Agents

The precise definition of the structural requirements for effective topoisomerase II poisoning by drug molecules is still an elusive issue. In the attempt to better define a pharmacophoric pattern, we prepared several conjugates combining the chemical features of two well-known topoisomerase II poisons, amsacrine and ametantrone. Indeed, an appropriate fusion geometry, which entails the anthracenedione moiety of ametantrone appropriately connected to the methanesulfonamidoaniline side chain of amsacrine, elicits DNA-intercalating properties, the capacity to inhibit the human topoisomerase IIβ isoform, and cytotoxic activity resembling that of the parent compounds. In addition, the properties of the lateral groups linked to the anthracenedione group play an important role in modulating DNA binding and cell cytotoxicity. Among the compounds tested, 10, 11, and 19 appear to be promising for further development. The structural requirements for cleavable complex stabilization by topoisomerase II poisons are still poorly understood. To better define a pharmacophoric pattern, several conjugates were prepared combining the chemical features of two well-known topoisomerase II poisons, amsacrine and ametantrone. Neither the planar chromophore nor the side chains alone are able to direct the strength of the interaction between the small molecule and the macromolecular complex.