Thiazole orange - Spermine conjugate: A potent human telomerase inhibitor comparable to BRACO-19.

In this report, we synthesized a series of TO conjugates containing different amino side chains and investigated their binding to telomeric G-quadruplex DNA (G4) using several biophysical methods including fluorometric titration and thermal denaturation monitored by fluorescence and circular dichroism. The composition of side chains strongly affects the binding of these molecules to G-quadruplex DNA. Incorporation of amino side chains increases the binding affinity of TO toward G4 but has a minimal effect on its selectivity for G4 over duplex DNA.