An insight into DNA binding properties of newly designed cationic δ,δ'‑diazacarbazoles: Spectroscopy, AFM imaging and living cells staining studies

Synthesize and multi-spectroscopic studies of zinc-naproxen nanodrug as DNA intercalator agent

The zinc-naproxen complex as a nano-drug (NanoD) was synthesized successfully via fast and effective ultrasound-assisted processes. The chemicophysical properties of the NanoD were determined using FT-IR, XRD, SEM, and EDX mapping analyses. The results confirmed the formation of the 55 nm NanoD laminates. The interaction of the obtained NanoD with calf thymus deoxyribonucleic acid (CT-DNA) was studied as well. Structural and topography changes of DNA in interaction with the NanoD were investigated by atomic force microscopy (AFM). The results of electronic absorption spectroscopy, the DNA-viscosity studies, and competition fluorescence spectroscopy showed that CT-DNA binds to the NanoD through the intercalative binding mode. The data of AFM analysis indicated swollen CT-DNA upon interaction with the NanoD. The in vitro investigation of cytotoxicity of the NanoD on HT-29 and Hep G2 cancer cells demonstrated high cytotoxicity activity of the NanoD than that of cisplatin in HT-29 cell line, especially at lower concentrations.

What Can Electrochemical Methods Offer in Determining DNA-Drug Interactions?

The interactions of compounds with DNA have been studied since the recognition of the role of nucleic acid in organisms. The design of molecules which specifically interact with DNA sequences allows for the control of the gene expression. Determining the type and strength of such interaction is an indispensable element of pharmaceutical studies. Cognition of the therapeutic action mechanisms is particularly important for designing new drugs. Owing to their sensitivity, simplicity, and low costs, electrochemical methods are increasingly used for this type of research. Compared to other techniques, they require a small number of samples and are characterized by a high reliability. These methods can provide information about the type of interaction and the binding strength, as well as the damage caused by biologically active molecules targeting the cellular DNA. This review paper summarizes the various electrochemical approaches used for the study of the interactions between pharmaceuticals and DNA. The main focus is on the papers from the last decade, with particular attention on the voltammetric techniques. The most preferred experimental approaches, the electrode materials and the new methods of modification are presented. The data on the detection ranges, the binding modes and the binding constant values of pharmaceuticals are summarized. Both the importance of the presented research and the importance of future prospects are discussed.

Synthesis of new morpholine containing 3-amido-9-ethylcarbazole derivative and studies on its biophysical interactions with calf thymus DNA/HSA

In this work, we presented the synthesis and investigation of binding properties of the new morpholine containing 3-amido-9-ethylcarbazole derivative (CMR) to calf thymus DNA (ctDNA) and human serum albumin (HSA) by fluorescence spectroscopy, UV absorption spectroscopy and molecular docking method. A decrease in Stern-Volmer constants was obtained with increase in temperature; it shows that static quenching mechanism leads to formation of new CMR-DNA/HSA complexes, which have hydrophobic interaction as the predominant role in the binding modes. Also, binding properties of DNA were investigated with competition assays on two probes (EB and H33258) by absorption, ionic strength and iodide ion quenching methods. The results suggested that CMR entered into the minor groove binding on the A-T region of DNA. The spectral data further confirmed by molecular docking which elicited that CMR complexes have similar interaction and conformation trends to each target, DNA and HSA. The experimental and computational results show that CMR has been classified as a promising molecule in drug designing of other carbazole derivatives.Communicated by Ramaswamy H. Sarma.

Studies on the interaction of antibiotic drug rifampin with DNA and influence of bivalent metal ions on binding affinity

In this paper, the interaction between rifampin, a known antibiotic used against tuberculosis, and DNA helix is investigated by applying multiple biophysical and molecular modelling approaches in an aqueous solution at pH 7.4 and 5. It was proved that the fluorescence quenching of labeled probe DNA by rifampin is a result of the complex formation of rifampin in groove of DNA. Binding parameters were calculated using the logarithmic Hill equation to provide a quantitative term of the binding affinity between rifampin and DNA sites. The resulting ΔH⁰ = -122.76 ± 0.07 kJ/mol and ΔS⁰ = -308.19 ± 238.78 J/mol K confirms the role of the Van der Waals' forces and hydrogen bonding in the rifampin-DNA complexation. Furthermore, the influence of bivalent metal ions on the binding affinity was resulted in order of Cu(II) > Ca(II) > Co(II) > Zn(II).