Small Heterocyclic Ligands as Anticancer Agents: QSAR with a Model G-Quadruplex

Area of Science:

• Medicinal Chemistry
• Computational Chemistry
• Molecular Biology

Background:

• G-quadruplexes (GQs) are increasingly recognized as crucial targets in anticancer drug discovery.
• Heterocyclic compounds are known to interact with biological structures, often through stacking interactions.

Purpose of the Study:

• To quantify the interaction energies between novel heterocyclic ligands and a simplified G-quadruplex model.
• To establish a correlation between computed ligand-G-quadruplex affinities and experimental anticancer activity.

Main Methods:

• Utilized large-scale density functional theory (DFT) calculations to model the stacking of heterocyclic ligands with a simplified G-quadruplex structure (naked guanine quartets).
• Synthesized and characterized seven 4-aminoquinazolines and three 2-heteroaryl perimidines.
• Assessed the biological inhibitory activity (IC50) of the synthesized ligands against the human malignant melanoma A375 cell line.

Main Results:

• Computed stacking energies (affinities) for ten heterocyclic ligands with the G-quadruplex model.
• Established a statistically significant linear relationship between the computed GQ.L stacking energies and the experimental log(IC50) values.
• Identified specific heterocyclic structures with high affinity for GQs and potent anticancer activity.

Conclusions:

• The study provides a computational framework for predicting the anticancer potential of heterocyclic compounds based on their G-quadruplex binding affinity.
• The findings suggest that stacking interactions with G-quadruplexes represent a viable mechanism for anticancer activity.
• This approach can guide the design of novel anticancer agents targeting G-quadruplex structures.