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Updated: Jul 4, 2025

Measuring Biomolecular DSC Profiles with Thermolabile Ligands to Rapidly Characterize Folding and Binding Interactions
Published on: November 21, 2017
DNA Interactions and Biological Activity of 2,9-Disubstituted 1,10-Phenanthroline Thiosemicarbazone-Based Ligands and
Álvaro Nicolás1,2, Julia G Quero1, Marta Barroso1
1Universidad de Alcalá, Departamento de Química Orgánica y Química Inorgánica, Instituto de Investigación Química "Andrés M. del Río" (IQAR), 28805 Madrid, Spain.
Abstract:
Four 1,10-phenanthroline derivatives (1-4) were synthesized as potential telomeric DNA binders, three substituted in their chains with thiosemicarbazones (TSCs) and one 4-phenylthiazole derivative. The compounds were characterized using NMR, HRMS, FTIR-spectroscopy and combustion elemental analysis. Quadruplex and dsDNA interactions were preliminarily studied, especially for neutral derivative 1, using FRET-based DNA melting assays, equilibrium dialysis (both competitive and non-competitive), circular dichroism and viscosity titrations. The TSC derivatives bind and stabilize the telomeric Tel22 quadruplex more efficiently than dsDNA, with an estimated 24-fold selectivity determined through equilibrium dialysis for compound 1. In addition, cytotoxic activity against various tumor cells (PC-3, DU145, HeLa, MCF-7 and HT29) and two normal cell lines (HFF-1 and RWPE-1) was evaluated. Except for the 4-phenylthiazole derivative, which was inactive, the compounds showed moderate cytotoxic properties, with the salts displaying lower IC50 values (30-80 μM), compared to the neutral TSC, except in PC-3 cells (IC50 (1) = 18 μM). However, the neutral derivative was the only compound that exhibited a modest selectivity in the case of prostate cells (tumor PC-3 versus healthy RWPE-1). Cell cycle analysis and Annexin V/PI assays revealed that the compounds can produce cell death by apoptosis, an effect that has proven to be similar to that demonstrated by other known 1,10-phenanthroline G4 ligands endowed with antitumor properties, such as PhenDC3 and PhenQE8.
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