Spectrofluorometric and computational approaches for the interaction studies of aclonifen and bifenox with human serum albumin

Spectroscopic, electrochemical, and molecular docking studies of the interaction between the antihistamine drug desloratadine and dsDNA

Through the utilization of fluorescence spectroscopy, electrochemical, and molecular docking methods, this research investigates the interaction between the antihistamine drug desloratadine and calf thymus double-stranded DNA (ct-dsDNA). Deoxyguanosine (dGuo) and deoxyadenosine (dAdo) oxidation signals were diminished by incubation with varying concentrations of desloratadine, as determined by differential pulse voltammetry (DPV). This change was ascribed to desloratadine's binding mechanism to ct-dsDNA. The binding constant (Kb) between desloratadine and ct-dsDNA was determined to be 2.2 × 105 M-1 throughout electrochemical experiments. In order to further develop our comprehension of the interaction mechanism between desloratadine and ct-dsDNA, a series of spectroscopic experiments and molecular docking simulations were conducted. The Kb value was found to be 8.85 × 104 M-1 at a temperature of 25 °C by the use of fluorescence spectroscopic techniques. In summary, the utilization of electrochemical and spectroscopic techniques, alongside molecular docking investigations, has led to the prediction that desloratadine has the capability to interact with ct-dsDNA by groove binding.

Insights into interaction of triazine herbicides with three kinds of different alkyl groups (simetryne, ametryn and terbutryn) with human serum albumin via multi-spectral analysis

In this study, the interaction of triazine herbicides with three kinds of different alkyl groups (simetryne, ametryn and terbutryn) with human serum albumin (HSA) are investigated through UV-vis, fluorescence, and circular dichroism (CD) spectra. The mechanisms on the fluorescence quenching of HSA initiated by triazine herbicides are obtained using Stern-Volmer, Lineweaver-Burk and Double logarithm equations. The quenching rate constant (Kq), Stern-Volmer quenching constant (Ksv), binding constant (KA), thermodynamic parameters such as enthalpy change (∆H), entropy change (∆S) and Gibbs free energy (∆G) and number of binding site (n) are calculated and compared. The variations in the microenvironment of amino acid residues are studied by synchronous fluorescence spectroscopy. The binding sites and subdomains are identified using warfarin and ibuprofen as site probes. The conformational changes of HSA are measured using CD spectra. The results reveal that the triazine herbicides with different alkyl groups can interact with HSA by static quenching. The combination of the three herbicides and HSA are equally proportional, and the binding processes are spontaneous. Hydrophobic interaction forces play important roles in simetryne-HSA and ametryn-HSA, while the interaction of terbutryn-HSA is Van der Waals forces and hydrogen bonding. Moreover, the three herbicides can bind to HSA at site I (sub-domain IIA) more than site II (subdomain IIIA), and combine with tryptophan (Trp) more easily than tyrosine (Tyr) residues, respectively. By comparison, the order of interaction strength is terbutryn-HSA > ametryn-HSA > simetryne-HSA. Terbutryn can destroy the secondary structure of HSA more than simetryne and ametryn, and the potential toxicity of terbutryn is higher. It is expected that the interactions of triazine herbicides with HSA via multi-spectral analysis can offer some valuable information for studying the toxicity and the harm of triazine herbicides on human health at molecular level in life science.

Unravelling the molecular interactions of phenyl isothiocyanate and benzoyl isothiocyanate with human lysozyme: Biophysical and computational analyses

Phenyl isothiocyanate and benzoyl isothiocyanate are the phytochemicals present in the Brassicaceae family. They have antibacterial, antiapoptotic and antifungal properties. Protein-small molecule interaction studies are done to assess the changes in structure, dynamics, and functions of protein and to decipher the binding mechanism. This study is based on the comparative binding of PT and BT with human lysozyme using in vitro and computational techniques. UV, fluorescence emission, and FRET spectra gave insight into the complex formation, quenching mechanism, and binding parameters. Both PT and BT quenched the intrinsic fluorescence of Lyz by a static quenching mechanism. Synchronous, 3D fluorescence and CD spectroscopy substantiated conformational and microenvironmental alterations in the Lyz. The metal ions and β-cyclodextrin had a pronounced effect on the binding strength of Lyz-PT and Lyz-BT complexes. Accessible surface area analysis was determined to characterise the amino acid residue packing. Molecular docking further validated the wet lab experimental results.

Hapten synthesis and a colloidal gold immunochromatographic strip assay to detect nitrofen and bifenox in fruits

In this study, we synthesized two haptens similar in structure to nitrofen (NIT), and screened out five monoclonal antibodies with the ability to recognize NIT and bifenox (BIF) by competitive ELISA, with the lowest IC₅₀ values of 0.87 ng mL^-1 and 0.86 ng mL^-1, respectively. The antibody 5G7 was selected to be combined with colloidal gold to establish a lateral flow immunochromatographic assay strip. This method was shown to qualitatively and quantitatively detect the residues of NIT and BIF in fruit samples. The visual limits of detection for qualitative detection were 5 μg kg^-1 and 10 μg kg^-1 for NIT and BIF, respectively. The calculated limits of detection for quantitative detection were 0.75 μg kg^-1, 1.77 μg kg^-1 and 2.55 μg kg^-1 respectively, for nitrofen in orange, apple and grapes, and 3.54 μg kg^-1, 4.96 μg kg^-1 and 5.26 μg kg^-1, respectively, for bifenox. Thus the strip assay could be used for rapid analysis of fruit samples.