Using a build-and-click approach for producing structural and functional diversity in DNA-targeted hybrid anticancer agents.

An efficient screening method was developed for functionalized DNA-targeted platinum-containing hybrid anticancer agents based on metal-mediated amine-to-nitrile addition, a form of "click" chemistry. The goal of the study was to generate platinum-acridine agents for their use as cytotoxic "warheads" in targeted and multifunctional therapies. This was achieved by introducing hydroxyl, carboxylic acid, and azide functionalities in the acridine linker moiety and by varying the nonleaving groups attached to platinum. The assay, which was based on microscale reactions between 6 platinum-nitrile complexes and 10 acridine derivatives, yielded a small library of 60 platinum-acridines. Reactions were monitored, and product mixtures were quantitatively analyzed by automated in-line high-performance liquid chromatography-electrospray mass spectrometry (LC-ESMS) analysis and subjected to cell viability screening using a nonradioactive cell proliferation assay. The new prescreening methodology proves to be a powerful tool for establishing structure-activity relationships and for identifying target compounds.