Application of the SwitchSense Technique for the Study of Small Molecules’ (Ethidium Bromide and Selected Sulfonamide Derivatives) Affinity to DNA in Real Time

The discovery and introduction of the switchSense technique in the chemical laboratory have drawn well-deserved interest owing to its wide range of applications. Namely, it can be used to determine the diameter of proteins, alterations in their tertiary structures (folding), and many other conformational changes that are important from a biological point of view. The essence of this technique is based on its ability to study of the interactions between an analyte and a ligand in real time (in a buffer flow). Its simplicity, on the other hand, is based on the use of a signaling system that provides information about the ongoing interactions based on the changes in the fluorescence intensity. This technique can be extremely advantageous in the study of new pharmaceuticals. The design of compounds with biological activity, as well as the determination of their molecular targets and modes of interactions, is crucial in the search for new drugs and the fight against drug resistance. This article presents another possible application of the switchSense technique for the study of the binding kinetics of small model molecules such as ethidium bromide (EB) and selected sulfonamide derivatives with DNA in the static and dynamic modes at three different temperatures (15, 25, and 37 °C) each. The experimental results remain in very good agreement with the molecular dynamics docking ones. These physicochemical insights and applications obtained from the switchSense technique allow for the design of an effective strategy for molecular interaction assessments of small but pharmaceutically important molecules with DNA.

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.

Photosensitive and pH-dependent activity of pyrazine-functionalized carbazole derivative as promising antifungal and imaging agent

Carbazole skeleton plays a significant role as a structural scaffold of many pharmacologically active compounds. Pyrazine-functionalized carbazole derivative was constructed by coupling 2-amino-5-bromo-3-methylaminepyrazine (ABMAP) into 3 and 6 positions of the carbazole ring. Multi-experimental methods were used, e.g., potentiometric, spectroscopic (ATR, UV, XRD powder,1H and13C NMR), electrochemical (cyclic voltammetry), and optical techniques, to receive the complete structural analysis, physicochemical (pKa, logP) and biological profile of a new carbazole derivative with acronym 3,6-PIRAMICAR. The interaction ability of the compound studied with potential cellular targets like Calf Thymus DNA (CT-DNA), or Bovine Serum Albumin (BSA) were also taken into account. Experiments showed the existence of strong binding, but no DNA or BSA cleavage was observed. The comparative analyzes of compounds anti-Candida action clearly show pH-dependent antifungal activity of 3,6-PIRAMICAR, which was strongly stimulated in the acidic media. Surprisingly, the titled compound turn out to be much more effective (14 times by MIC50; 8 times by MIC; c.a. 4 times by MFC) against Candida krusei than fluconazole at pH 4.

Hydrogen bonding and protonation effects in amino acids' anthraquinone derivatives - Spectroscopic and electrochemical studies

Six novel amino acid chromophores were synthesized and their spectroscopic, acid-base, and electrochemical properties are discussed in this work. In studied compounds, selected amino acid residues (l-Aspartic acid, l-Glutamic acid, l-Glutamine, l-Histidine, l-Lysine, l-Arginine) are attached to the 1-(piperazine) 9,10-anthraquinone skeleton via the amide bond between the carboxyl group of amino acid and nitrogen atom of the piperazine ring. All derivatives have been characterized using a variety of spectroscopic techniques (mass spectrometry, 1HNMR, UV-Vis, IR spectroscopy), acid-base (electrochemical and UV-Vis) titrations, and cyclic voltammetry methods. Basing on observed experimental effects, supported by quantum chemical simulations, the structure-properties links were established. They are indicative of the specific interactions within and/or in-between amino acid side groups, which are prone to form both, intra- and intermolecular hydrogen bonds as well as electrostatic interactions with the anthraquinone system.