Pyridine Derivative of the Natural Alkaloid Berberine as Human Telomeric G<sub>4</sub>-DNA Binder: A Solution and Solid-State Study
Francesco Papi, Carla Bazzicalupi, Marta Ferraroni, Giulia Ciolli, Paolo Lombardi, Asma Yasmeen Khan, Gopinatha Suresh Kumar, Paola Gratteri
Abstract
Telomerase is an enzyme deputed to the maintenance of eukaryotic chromosomes; however, its overexpression is a recognized hallmark of many cancer forms. A viable route for the inhibition of telomerase in malignant cells is the stabilization of G-quadruplex structures (G4) at the 3′ overhang of telomeres. Berberine has shown in this regard valuable G4 binding properties together with a significant anticancer activity and telomerase inhibition effects. Here, we focused on a berberine derivative featuring a pyridine containing side group at the 13th position. Such modification actually improves the binding toward telomeric G-quadruplexes and establishes a degree of selectivity in the interaction with different sequences. Moreover, the X-ray crystal structure obtained for the complex formed by the ligand and a bimolecular human telomeric quadruplex affords a better understanding of the 13-berberine derivatives behavior with telomeric G4 and allows to draw useful insights for the future design of derivatives with remarkable anticancer properties.