The effect of non-specific binding of Pd(II) complexes with N-heteroaromatic hydrazone ligands on the protein structure

Previously, the cytotoxic actions of five Pd(II) complexes with bidentate N-heteroaromatic chelators (complexes 1–5) on a palette of several cancer cell lines were investigated. However, the results of the cytotoxic activity did not correlate with the hydrophobic character of the complexes. To gain further insight into the structure–activity relationship, essential for the design of novel potential drugs, other factors, such as non-specific interactions with cellular proteins, have to be taken into account. To explore the potential non-specific influence of the complexes on protein structures, ovalbumin (OVA) was chosen as a model system to mimic cellular non-specific crowding environments with high protein concentrations. A Fourier-transform infrared spectroscopy study implied that the binding of 3 and 4 led to only moderate alternations in the secondary structures of the protein, without the possibility to penetrate into hydrophobic core of the protein and disruption of protein native fold. Contrary, the effect of complex 5 on OVA secondary structures was concentration-dependent. While the lower concentration of complex 5 had no effect on OVA structure, a doubled concentration of complex 5 led to complete disruption of the content native-like secondary structures. The concentration-dependent effect of complex 5 on the changes in secondary structures and considerable increase in the exposure of OVA hydrophobic surfaces to water may be related to a potential crosslinking that leads to OVA aggregation. © 2022 Serbian Chemical Society. All rights reserved

Solvatochromic properties of novel dyes derived from stilbazolium salts

Pet novih jedinjenja na bazi stilbazolijum-soli, D-π-A strukture, sintetizovano je i detaljno okarakterisano. Solvatohromizam sintetizovanih jedinjenja ispitan je korišćenjem četiri rastvarača različite prirode pomoću UV-Vis spektroskopije. Takođe, ispitan je uticaj različitih elektron-donorskih grupa na solvatohromna svojstva molekula. Zahvaljujući prirodi kvaternarnog atoma azota, piridinijumov prsten u ovim jedinjenjima ispoljava jak elektron-akceptorski karakter, promovišući intramolekulski transfer naelektrisanja. Zahvaljujući ovom svojstvu, jedinjenja na bazi stilbazolijum-soli su primenu našla u brojnim granama industrije i nauke.Five novel dyes derived from stilbazolium salts, bearing D-π-A structure, were synthesized and completely characterized. The solvatochromism of the synthesized dyes was investigated using four different solvents by means of UV-Vis spectroscopy. Also, the influence of different electron-donor groups on the solvatochromic properties of dyes was examined. Due to the nature of the quaternary nitrogen atom, the pyridinium ring in these compounds exhibits a strong electron-accepting character, promoting intramolecular charge transfer. This property has enabled compounds derived from stilbazolium salts to find applications in numerous branches of industry and science