Issue 45, 2016

Luminescent ruthenium polypyridyl complexes with extended ‘dppz’ like ligands as DNA targeting binders and cellular agents

Abstract

Four new Ru(II) polypyridyl complexes that contain an extended aromatic moiety derived from pyrazino[2,3-h]dipyrido[3,2-a:2′,3′-c]phenazine and either 1,10-phenanthroline (phen) or 1,4,5,8-tetraazaphenanthrene (TAP) have been synthesized, their solid state X-ray crystal structure determined and their photophysical and biological properties evaluated. Their interactions with DNA have been studied, and they have been tested for their potential as photodynamic therapeutic (PDT) agents in the treatment of cancer. A practical modification of a method by Carter, Rodriguez and Bard has been introduced and used to calculate binding parameters for the complexes which show a strong affinity for DNA with binding constants in the order of 107 M−1 (in 10 mM phosphate buffer). The complexes containing phen as an ancillary ligand become emissive upon binding to DNA (“light switch effect”), but do not show selective cytotoxicity upon light irradiation. On the other hand, the TAP complexes, which show an inverse “light switch effect” (emission quenched upon binding to DNA), are strongly photo-toxic suggesting their use in Photodynamic Therapy (PDT). In HeLa cells the best PDT agent shows an IC50 value (light) = 4 μM vs. IC50 value (dark) = 62 μM.

Graphical abstract: Luminescent ruthenium polypyridyl complexes with extended ‘dppz’ like ligands as DNA targeting binders and cellular agents

Supplementary files

Article information

Article type
Paper
Submitted
29 Sep 2016
Accepted
21 Oct 2016
First published
21 Oct 2016

Dalton Trans., 2016,45, 18208-18220

Luminescent ruthenium polypyridyl complexes with extended ‘dppz’ like ligands as DNA targeting binders and cellular agents

B. C. Poulsen, S. Estalayo-Adrián, S. Blasco, S. A. Bright, J. M. Kelly, D. C. Williams and T. Gunnlaugsson, Dalton Trans., 2016, 45, 18208 DOI: 10.1039/C6DT03792E

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