Multicharged phthalocyanines as selective ligands for G-quadruplex DNA structures

Catarina I.V. Ramos, Susana P. Almeida, Leandro M.O. Lourenço, Patrícia M.R. Pereira, Rosa Fernandes, M. F. Amparo Faustino, João P.C. Tomé, Josué Carvalho, Carla Cruz, M. P.M.S. Graça Neves

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38 Scopus citations


The stabilization of G-Quadruplex DNA structures by ligands is a promising strategy for telomerase inhibition in cancer therapy since this enzyme is responsible for the unlimited proliferation of cancer cells. To assess the potential of a compound as a telomerase inhibitor, selectivity for quadruplex over duplex DNA is a fundamental attribute, as the drug must be able to recognize quadruplex DNA in the presence of a large amount of duplex DNA, in the cellular nucleus. By using different spectroscopic techniques, such as ultraviolet-visible, fluorescence and circular dichroism, this work evaluates the potential of a series of multicharged phthalocyanines, bearing four or eight positive charges, as G-Quadruplex stabilizing ligands. This work led us to conclude that the existence of a balance between the number and position of the positive charges in the phthalocyanine structure is a fundamental attribute for its selectivity for G-Quadruplex structures over duplex DNA structures. Two of the studied phthalocyanines, one with four peripheral positive charges (ZnPc1) and the other with less exposed eight positive charges (ZnPc4) showed high selectivity and affinity for G-Quadruplex over duplex DNA structures and were able to accumulate in the nucleus of UM-UC-3 bladder cancer cells.

Original languageEnglish
Article number733
Issue number4
StatePublished - Feb 18 2019


  • Circular dichroism
  • G-Quadruplexes
  • G4-FID
  • Hyperchromism
  • Multicharged phthalocyanines
  • Salmon sperm DNA
  • Selectivity
  • Telomerase inhibition
  • UV-Vis


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