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

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 H-1, C-13, and {N-15,H-1} 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 IC50 values of 35M. 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)x10(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. [GRAPHICS]