Crystal structure and cytotoxic activities of a bis(pyrrolyl-imine) gold(III) complex

• Published in: Journal of coordination chemistry 2016-09, Vol.69 (18), p.2707-2722
• Main Authors: Profirio, Daniel De Moraes, Paiva, Raphael Enoque Ferraz De, Abbehausen, Camilla, Cuin, Alexandre, Masciocchi, Norberto, Machado, Daisy, Lancellotti, Marcelo, Corbi, Pedro Paulo, Formiga, André Luiz Barboza
• Format: Article
• Language: English
• Subjects: Binding; Constants; Crystal structure; cytotoxic activity; Cytotoxicity; Deoxyribonucleic acid; DFT; Dichroism; DNA; Fluorescence; gold(III); Pyrroles; Pyrrolyl-imine; Quenching; Spectroscopic analysis
• ISSN: 0095-8972; 1029-0389
• DOI: 10.1080/00958972.2016.1214949

A gold(III) complex with N,N′-ethylenebis(pyrrol-2-yl-methyleneamine) (H 2 pyren) was synthesized and characterized by physicochemical and spectroscopic measurements. Density functional theory (DFT) studies and cytotoxic assays were performed. Infrared, mass spectrometry, and 1 H, 13 C, and { 15 N, 1 H} nuclear magnetic resonance analyses indicate that pyren is deprotonated and gold(III) is four coordinate in a square planar environment, with the pyrrole and imine nitrogens as donors. The structure was confirmed by powder X-ray diffraction and confirmed as a minimum of the potential energy surface by DFT. Cytotoxic activity of [Au(pyren)] + was active against three tumorigenic cell lines with IC 50 values of 35 μM. Interaction studies with CT-DNA by fluorescence and competition with ethidium bromide (EB) showed a quenching of the emission band of DNA with a Stern-Volmer quenching constant value of (3.0 ± 0.1) × 10 4  M −1 and a decrease in fluorescence quenching of EB-DNA system, respectively, confirming that DNA is a possible target for the complex via an intercalative binding, which was confirmed by DNA conformational changes observed with circular dichroism spectroscopy.