5-<i>N</i>-Methylated Quindoline Derivatives as Telomeric G-Quadruplex Stabilizing Ligands: Effects of 5-<i>N</i> Positive Charge on Quadruplex Binding Affinity and Cell Proliferation
ligands possess a positive charge at the 5- N position of the aromatic quindoline scaffold. The quadruplex binding of these compounds was evaluated by circulardichroism (CD) spectroscopy, fluorescence resonance energy transfer (FRET) melting assay, polymerase chain reaction (PCR) stop assay, nuclearmagneticresonance (NMR), and molecular modeling studies. Introduction of a positive charge not only