# Combining Cyclic Triimidazo Triazine Core With Ethynyl‐N‐Methyl‐Pyridinium Groups for Targeting G‐Quadruplex Structures

## TL;DR

Scientists designed and tested new compounds that target DNA structures linked to cancer, finding that specific chemical linkers improve their effectiveness.

## Contribution

A new class of compounds with alkyne linkers that better stabilize G-quadruplex DNA and show improved anticancer activity.

## Key findings

- Trisubstituted compounds showed the highest G-quadruplex stabilization.
- Mono- and disubstituted derivatives had higher selectivity for G-quadruplexes over DNA duplexes.
- Alkyne linkers enhanced both G-quadruplex stabilization and anticancer activity.

## Abstract

The synthesis and characterization of a mini‐library of cyclic triimidazo triazine (TT) derivatives functionalized with one, two, or three ethynyl‐N‐methyl‐pyridinium moieties are reported here. These compounds were designed with the aim of targeting cancer‐related DNA G‐quadruplex structures. The newly synthesized compounds were tested for their ability to bind G‐quadruplexes from both telomeric and oncogene promoter sequences using an affinity chromatography‐based assay, spectroscopic and electrophoretic techniques, as well as molecular docking analysis. The obtained results demonstrated the effective capacity of the investigated compounds to specifically recognize the selected G‐quadruplex models, with their TT cores targeting the outer G‐quartets and their positively charged N‐methyl‐pyridinium groups interacting with the top edge of G‐quadruplex grooves. Notably, the trisubstituted cyclic triimidazole compounds showed higher stabilizing properties than the related disubstituted derivatives, which in turn were stronger binders than their monosubstituted analogs. However, the mono‐ and disubstituted derivatives showed higher G‐quadruplex versus duplex recognition selectivity compared with the trisubstituted ones. Altogether, the biophysical experiments, also in agreement with the biological assays, underlined the advantage of introducing an alkyne linker between the triimidazole core and the methylpyridinium group, proving to be beneficial to increase both the stabilizing effects on the G‐quadruplexes and the anticancer activity compared with the analogs of the same family lacking the alkyne linker.

A mini‐library of cyclic triimidazo triazine derivatives functionalized with one, two, or three ethynyl‐N‐methyl‐pyridinium moieties was synthesized, characterized for the interaction with cancer‐related G‐quadruplexes, and tested in antiproliferative activity screenings on human cancer cells. The alkyne linker between the triimidazole core and the N‐methylpyridinium group proved to be beneficial for both the stabilization of the G‐quadruplexes and the anticancer activity.