DNA and RNA Noncovalent Interaction of Platinum(II) Polypyridine Complexes

Deciphering the effect of hydrophobicity on protein binding interaction in cobalt(II) complexes by multispectroscopic and computational methods

In the present work, we report the synthesis, characterization of two cobalt complexes (1 and 2) and their HSA binding studies by multispectroscopic methods. Hirshfeld surfaces analysis and fingerprint plot analysis were carried out to identify intermolecular interactions viz., N-H···O, O-H···O and C-H···O linkages in crystal framework of the complexes. Density functional theory (DFT) studies were carried out to ascertain the electronic structure and molecular geometry of the complexes 1 and 2, and determine the localization of HOMO and LUMO in the complexes. A comparative in vitro interaction study of complex 1 and 2 with human serum albumin protein was carried out by employing UV-vis, fluorescence, circular dichroism, FTIR and molecular docking techniques. Interestingly, the HSA binding affinity of complex 2 was found to be more than complex 1 which was evidenced from the higher binding constant values owing to its strong hydrophobic topology. Further, a significant conformational change in microenvironment of HSA was noticed upon binding with complexes 1 and 2, nevertheless more perturbations were noticed in presence of complex 1. Molecular docking studies were carried out to validate the spectroscopic results and ascertain the preferential binding mode of complexes at the specific target site of HSA.Communicated by Ramaswamy H. Sarma.

Design and synthesis of a DNA intercalative half-sandwich organoruthenium(ii)–chromone complex: cytotoxicity evaluation and topoisomerase Iα inhibition assay

A half-sandwich organoruthenium(ii)–chromone complex acts as a potential topoisomerase I inhibitor.

Design, synthesis and characterization of novel chromone based-copper(ii) antitumor agents with N,N-donor ligands: comparative DNA/RNA binding profile and cytotoxicity

A series of new chromone based-Cu(ii) complexes 1-3 derived from bioactive pharmacophore, 3-formylchromone and N,N-donor ligands viz., 1,10-phenanthroline, 2,2'-bipyridine and 1R,2R-DACH were synthesized as potential antitumor agents and thoroughly characterized by UV-vis, FT-IR, EPR, ESI-MS and elemental analysis. Single X-crystal diffraction studies of complex 2 revealed triclinic P1̄ space group with square pyramidal geometry around the Cu(ii) center. Comparative in vitro binding studies with ct-DNA and tRNA were carried out using absorption and emission titration experiments which revealed intercalative mode of binding with higher binding propensity of complexes 1-3 towards tRNA as compared to ct-DNA. Additionally, complex 1 exhibited high binding affinity among all the three complexes due to the involvement of phen co-ligands via π-stacking interactions in between nucleic acid base pairs. Furthermore, Hirshfeld surface analysis was carried out for complex 2 to investigate various intra and intermolecular non-covalent interactions (H-bonding, C-H⋯π etc.) accountable for stabilization of crystal lattice. The cleavage activity of complex 1 was performed by gel electrophoretic assay with pBR322 DNA and tRNA which revealed efficient DNA/tRNA cleaving ability of complex, suggesting tRNA cleavage both concentration and time dependent. Furthermore, in vitro cytotoxic activity of complexes 1-3 on a selected panel of human cancer cell lines was performed which revealed that all three complexes exhibited remarkably good cytotoxic activity with GI50 value < 10 μg mL-1 (<20 μM).

Carbohydrates and Charges on Oligo(phenylenethynylenes): Towards the Design of Cancer Bullets

Two new tetralkylammonium-OPEs, bearing one or two positively charged groups directly linked to the aromatic residues and two β-d-glucopyranose terminations, were synthesized. Their peculiar structural features, joining the biologically relevant sugar moieties, flat aromatic cores and positive charges, make these luminescent dyes soluble in aqueous media and able to strongly interact with DNA. As a result of UV/Vis spectral variations, DNA melting temperature measures, viscometric titrations and induced CD, we propose a partial insertion of the OPEs aromatic core into the helix, stabilized by glucose H-bonding with the groups accessible from the grooves. This interaction leads to the quenching of the OPE luminescence due to guanine reduction. The biocompatibility of the monocationic OPE with healthy and cancer cells, and the reduction of proliferation in HEp-2 cancer cells induced by the dicationic one, make this class of compounds promising for future biological applications.

Single X-ray crystal structure, DFT studies and topoisomerase I inhibition activity of a tailored ionic Ag(i) nalidixic acid–piperazinium drug entity specific for pancreatic cancer cells

DFT studies, Topo I inhibition assay and cytotoxic activity of novel ionic Ag(i) nalidixic acid–piperazinium molecular entity.

Mechanistic insights into a novel chromone-appended Cu(II) anticancer drug entity: in vitro binding profile with DNA/RNA substrates and cytotoxic activity against MCF-7 and HepG2 cancer cells

A new chromone-appended Cu(ii) drug entity () was designed and synthesized as a potential anticancer chemotherapeutic agent. The structural elucidation was carried out thoroughly by elemental analysis, FT-IR, EPR, ESI-MS and single crystal X-ray crystallography. Complex resulted from the in situ methoxylation reaction of the 3-formylchromone ligand and its subsequent complexation with the copper nitrate salt in a 2 : 1 ratio, respectively. crystallized in the monoclinic P21/c space group possessing the lattice parameters, a = 8.75 Å, b = 5.07 Å, c = 26.22 Å, α = γ = 90°, β = 96.3° per unit cell. Furthermore, in vitro interaction studies of with ct-DNA and tRNA were carried out which suggested more avid binding propensity towards the RNA target via intercalative mode, which was reflected from its Kb, K and Ksv values. The gel electrophoretic mobility assay was carried out on the pBR322 plasmid DNA substrate, to ascertain the cleaving ability and the mechanistic pathway in the presence of additives, and the results revealed the efficient cleaving ability of via the oxidative pathway. In vitro cell growth inhibition via the MTT assay was carried out to evaluate the cytotoxicity of complex and IC50 values were found to be in the range of 5-10 μg mL(-1) in HepG2 and MCF-7 cancer cell lines, which were found to be much lower than the IC50 values of previously reported similar Cu(ii) complexes. Additionally, in the presence of , reactive oxygen species (ROS) and thiobarbituric acid reactive substance (TBARS) levels in the tested cancer cell lines increased significantly, coupled with reduced glutathione (GSH) levels. Thus, our results suggested that ROS plays an important role in cell apoptosis induced by the Cu(ii) complex and validates its potential to act as a robust anticancer drug entity.

Interaction of Cd(ii) and Ni(ii) terpyridine complexes with model polynucleotides: a multidisciplinary approach

The study of the intercalation of both complexes, evidenced by CD and fluorescence spectroscopy and supported by QM/MM calculations, broadens the experimental and theoretical background on drugs/DNA interactions.

Multispectral studies of DNA binding, antioxidant and cytotoxic activities of a new pyranochromene derivative

The binding properties of a new pyranochromene derivative, 2-amino-4-(3-hydroxyphenyl)-5-oxo-4H, 5H-pyrano-[3, 2-c] chromene-3-carbonitrile (3-HC) with calf thymus DNA (ctDNA) have been investigated by UV-vis absorption, circular dichroism, fluorescence spectroscopy and viscosity measurement. These results indicated that 3-HC can interact with DNA through non-intercalative mode and the intrinsic binding constant (Kb) for 3-HC with DNA was estimated to be 3.6 × 10(3)M(-1). The antioxidant activity experiments show that 3-HC also exhibit good antioxidant activity in DPPH free radical scavenging and ferric reducing ability methods. Moreover, 3-HC exhibited cytotoxic activity against K562, human chronic myelogenous leukemia cells, with IC50 value of 146 μM and the cells responded to the treatment with mostly through apoptosis.

DNA/RNA binding and anticancer/antimicrobial activities of polymer-copper(II) complexes

Water soluble polymer-copper(II) complexes with various degrees of coordination in the polymer chain were synthesized and characterized by elemental analysis, IR, UV-visible and EPR spectra. The DNA/RNA binding behavior of these polymer-copper(II) complexes was examined by UV-visible absorption, emission and circular dichroism spectroscopic methods, and cyclic voltammetry techniques. The binding of the polymer-copper(II) complexes with DNA/RNA was mainly through intercalation but some amount of electrostatic interaction was also observed. This binding capacity increased with the degree of coordination of the complexes. The polymer-copper(II) complex having the highest degree of coordination was subjected to analysis of cytotoxic and antimicrobial properties. The cytotoxicity study indicated that the polymer-copper(II) complexes affected the viability of MCF-7 mammary carcinoma cells, and the cells responded to the treatment with mostly through apoptosis although a few cells succumbed to necrosis. The antimicrobial screening showed activity against some human pathogens.