DNA Binding Studies and Cytotoxicity of a Dinuclear Pt super(II) Diazapyrenium-Based Metallo-supramolecular Rectangular Box

The interaction with native DNA of a 2,7-diazapyrenium-based ligand 1 and its Pt super(II) rectangular metallacycle 2 is explored through circular and linear dichroism and fluorescence spectroscopies. The metal-free ligand 1 binds through intercalation, with a binding constant of approximately 510 super(5)M super(-1), whereas the metallacycle 2 binds and bends the DNA with a binding constant of 710 super(6)M super(-1). PCR assays show that metallo-supramolecular box 2 interferes with DNA transactions in vitro whereas the intercalator 1 does not. The metallacycle is active against four human cancer cell lines, with IC sub(50) values ranging between 3.1 and 19.2 mu M and shows similar levels of efficacy, but a different spectrum of activity, to cisplatin. Boxed in: Supramolecular boxes bind DNA, prevent DNA transactions and inhibit growth of cancer cells. The interaction of a 2,7-diazapyrenium-based ligand and its Pt super(II) rectangular metallacycle with native DNA (see scheme) was explored. The metallacycle is active against four human cancer cell lines, and shows similar levels of efficacy, but a different spectrum of activity, to cisplatin.