Low-dimensional compounds containing bioactive ligands. Part IX: Synthesis, structures, spectra, in vitro antimicrobial and anti-tumor activities and DNA binding of Pd(II) complexes with 7-bromo-quinolin-8-ol

Abstract

© 2017 Elsevier Ltd New Pd(II) complexes with 7-bromo-quinolin-8-ol (BrQ), [Pd(BrQ)2] (1a) and (1b) and HBrQ[PdCl2(BrQ)] (2) have been synthesized and characterized. X-ray structure analysis of 1a and 1b revealed that the molecular structures of these square-planar polymorphs are very similar, nevertheless in the supramolecular structure the molecules are differently arranged and held by different intermolecular forces. The structure of 2 in DMSO solution was elucidated using one- and two-dimensional NMR experiments which showed that the complex decomposes to BrQ ligand. Antimicrobial activity of soluble complex 2 was tested by determining the minimum inhibitory concentration and minimum microbicidal concentration against 9 strains of bacteria and 5 strains of fungi; its activity on Proteus mirabilis is more than 250 times higher than a positive control. Complex 2 is also significantly more cytotoxic against human colorectal cancer cells HCT116 than cisplatin at all tested concentrations and this effect is particularly pronounced at low concentrations; cytotoxicity of BrQ is four times higher than cytotoxicity of 2 at these concentrations and is selectively cytotoxic. Interaction of 2 with DNA was investigated using UV–VIS spectroscopy and fluorescence spectroscopy; the binding studies indicate that complex 2 can interact with ctDNA through intercalation mechanism.