A resonance light-scattering off–on system for studies of the selective interaction between adriamycin and DNA

Monitoring of DNA structural changes after incorporation of the phenylpyrazole insecticide fipronil

The use of insecticides presents a risk to the environment because they can accumulate in the water, soil, air, and organisms, endangering human and animal health. It is therefore essential to investigate the effects of different groups of insecticides on individual biomacromolecules such as DNA. We studied fipronil, which belongs to the group of phenylpyrazole insecticides. The interaction of fipronil with calf thymus DNA was investigated using spectroscopic methods (absorption and fluorescence spectroscopy) complemented with infrared spectroscopy and viscosity measurement. Fluorescence emission spectroscopy showed the formation of a fipronil/DNA complex with a combined static and dynamic type of quenching. The binding constant was 4.15 × 103 L/mol. Viscosity changes were recorded to confirm/disconfirm the intercalation mode of interaction. A slight change in DNA viscosity in the presence of fipronil was observed. The phenylpyrazole insecticide does not cause significant conformational changes in DNA structure or increase of its chain length. We hypothesize that fipronil is incorporated into the minor groove of the DNA macromolecule via hydrogen interactions as indicated by FT-IR and CD measurements.

The effect of neonicotinoid insecticide thiacloprid on the structure and stability of DNA

The application of pesticides and chemical fertilizers constitutes a potential risk to human and animals due to the presence of their residues in the food. Thiacloprid belongs to a group of neonicotinoid insecticides. It shows a cytotoxic/cytostatic effect in human peripheral blood lymphocytes probably due to DNA damage. The use of thiacloprid is increasingly widespread worldwide, therefore is very important the assessment of its possible genotoxic and cytotoxic effects on a living organism. That is the reason why we studied the thiacloprid influence on the structure and stability of DNA in presented work. We have been studied the thiacloprid interaction with calf thymus DNA. Association constant was determined by fluorescence spectroscopy using equilibrium receptor-ligand binding analysis. The thermal denaturation of DNA was used to identify the mode of interaction. Viscosity changes were recorded to confirm/disconfirm the intercalation mode of interaction. Given the results, we can conclude that neonicotinoid pesticide thiacloprid destabilizes DNA. It changes the structure and stability of DNA through binding into the minor groove by hydrophobic or hydrogen interactions.

Probing the binding of insecticide permethrin to calf thymus DNA by spectroscopic techniques merging with chemometrics method

The binding of permethrin (PE) with calf thymus DNA (ctDNA) in physiological buffer (pH 7.4) was investigated by ultraviolet-visible (UV-vis) absorption, fluorescence, circular dichroism (CD), and Fourier transform infrared (FT-IR) spectroscopy merging with multivariate curve resolution-alternating least-squares (MCR-ALS) chemometrics approach. The MCR-ALS was applied to resolve the combined spectroscopic data matrix, which was obtained by UV-vis and fluorescence methods. The concentration profiles of PE, ctDNA, and PE-ctDNA complex and their pure spectra were then successfully obtained. The PE molecular was found to be able to intercalate into the base pairs of ctDNA as evidenced by decreases in resonance light-scattering signal and iodide-quenching effect and increase in ctDNA viscosity. The results of FT-IR spectra indicated that PE was prone to bind to G-C base pairs of ctDNA, and the molecular docking studies were used to validate and clarify the specific binding. The observed changes in CD signals revealed that the DNA turned into a more highly wound form of B-conformation. The calculated thermodynamic parameters, enthalpy change (ΔH°) and entropy change (ΔS°), suggested that hydrogen bonds and van der Waals forces played a predominant role in the binding of PE to ctDNA.