Selective visualization of DNA G-quadruplex structures in live cells with 1-methylquinolinium-based molecular probes: The importance of indolyl moiety position towards specificity

Quadruplex detection in human cells

“…Higher-resolution images were collected with a styryl-substituted TO referred to as 4a, 85 which was useful for labelling both live and fixed human prostate cancer PC3 cells (5 µM, 15 min), the latter providing a clear visualization of a nucleolar accumulation of the dye (Figure 4b). The p-conjugation was further expanded introducing 3-vinylindole arms but the images of live PC3 cells incubated with compound 3c (5 µM, 5 min) demonstrated, again, that the localization of foci remained globally centered on the nucleoli (Figure 4c), 86 without providing deeper insights into the localization of quadruplexes in cells. For instance, the cyanine CyT was found to be particularly sensitive to RNA quadruplexes and suited to the detection of RNA quadruplexes in living A459 cells (1.25 µM, 24 h), the foci being exclusively localized in the cytoplasm of the cells (Figure 5a).…”

Stabilization and fluorescence light-up of G-quadruplex nucleic acids using indolyl-quinolinium based probes

“…These considerations were discovered as the critical factors for the good fluorescence signal switch-on property for discriminating G4 DNA from other DNA structures. 57 Sun and co-workers reported planar and rotatable π-conjugated indole and pyridinium molecules linked by an ethylene bridge to improve the structural flexibility of the conjugated two ring co-planar system, demonstrating remarkable fluorescence discrimination between G4 DNA and other DNA tertiary structures. Xie and co-workers 58 reported indole- or pyrrole-substituted distyryl and mono-styryl dyes and studied their fluorescent light-up properties for G4 DNAs, duplex DNA, or single-stranded RNA.…”

Structurally diverse G-quadruplexes as the noncanonical nucleic acid drug target for live cell imaging and antibacterial study

“…Our group has also investigated some G4-DNA binding ligands developed recently in antibacterial studies. The G4ligands derived from the integration of 1-methylquinolinium and indole scaffolds 137,183 were found to show a certain degree of activity against a number of Gram-positive and Gramnegative bacterial strains. 184,185 A screening from a small library of G4-ligands developed by our group shows that c2 and c9 (Fig.…”