A complete multispectroscopic resolution on the fate of HSA upon interplay with three different glycosaminoglycans inspired silver nanoparticles and straightforward judgment of nanoparticles for recruitment as potent anticancer and antibacterial agent

Synthesis of water-soluble novel bioactive pyridine-based azo coumarin derivative and competitive cytotoxicity, DNA binding, BSA binding study, and in silico analysis with coumarin

The diazo coupliling reaction of 3- amino pyridine with coumarin in water medium produces water soluble 6-[3-pyridyl]azocoumarin. The synthesised compound has been fully charecterised by IR, NMR, and Mass spectroscopy. The frontier molecular orbital calculations reveal that 6-[3-pyridyl]azocoumarin is more biologically and chemically active in comparison to coumarin. The cytotoxicity evaluation confirms that 6-[3-pyridyl]azocoumarin is more active than coumarin against human brain glioblastoma cell lines, LN-229 with IC50 value 9.09 μM (IC50 value for coumarin is 9.9 μM). The compound (I) has been synthesized by coupling of diazotized solution of 3-aminopyridine with coumarin in an aqueous medium at ∼ pH 10. The structure of the compound (I) has been characterized using UV-vis, IR, NMR, and Mass spectral studies. Frontier molecular orbital calculations reveal that 6-[3-pyridyl]azocoumarin (I) is more active chemically and biologically in comparison to coumarin. IC50 value 9.09 and 9.9 μM of 6-[3-pyridyl]azocoumarin and coumarin respectively obtained in cytotoxicity evaluation confirms the enhanced activity of the synthesized compound against human brain glioblastoma cell lines, LN-229. The synthesized compound also shows strong binding interactions with DNA and BSA in comparison with coumarin. The DNA binding study shows groove binding interaction of the synthesized compound with CT-DNA. The nature of interaction, binding parameters and structural variations of BSA in the presence of the synthesized compound and coumarin have been evaluated using several usefull spectroscopy approaches such as UV -Vis, time resolved and stady state flurescence. The molecular docking interaction has been carried out to justify the experimental binding interaction with DNA and BSA.

Interactions of diclazuril enantiomers with serum albumins: Multi-spectroscopic and molecular docking approaches

In this work, multi-spectroscopic and molecular docking methods have been conducted in the investigation of enantioselective interactions between diclazuril enantiomers and human/bovine serum albumins (HSA/BSA). The binding constants between serum albumins (SAs) and diclazuril enantiomers revealed that SAs exhibited stronger binding affinity for (R)-diclazuril than (S)-enantiomer. In addition, the fluorescence quenching of SAs induced by diclazuril enantiomers was ascribed to static quenching mechanism, in which hydrogen bonds and Van der Waals forces were the main interactions. According to the thermodynamic study, binding of diclazuril enantiomers and SAs was an exothermic process driven by enthalpy change. Then, circular dichroism spectroscopy of SAs with diclazuril enantiomers revealed that the SAs conformation had changed in the presence of diclazuril. Moreover, molecular docking technology was applied in exploration of interactions between SAs and diclazuril enantiomers. The docking energy between SAs and (R)-diclazuril was larger than (S)-diclazuril, which indicated that the affinity of SAs with (R)-diclazuril was stronger than (S)-enantiomer. This work may provide valuable information for explaining differences in pharmacokinetics and residue elimination of diclazuril enantiomers in living organisms.

Probe into the Molecular Mechanism of Ibuprofen Interaction with Warfarin Bound to Human Serum Albumin in Comparison to Ascorbic and Salicylic Acids: Allosteric Inhibition of Anticoagulant Release

The release of anticoagulant drugs such as warfarin from human serum albumin (HSA) has been important not only mechanistically but also clinically for patients who take multiple drugs simultaneously. In this study, the role of some commonly used drugs, including s-ibuprofen, ascorbic acid, and salicylic acid, was investigated in the release of warfarin bound to HSA in silico. The effects of the aforementioned drugs on the HSA-warfarin complex were investigated with molecular dynamics (MD) simulations using two approaches; in the first perspective, molecular docking was used to model the interaction of each drug with the HSA-warfarin complex, and in the second approach, drugs were positioned randomly and distant from the binary complex (HSA-warfarin) in a physiologically relevant concentration. The results obtained from both approaches indicated that s-ibuprofen and ascorbic acid both displayed allosteric effects on the release of warfarin from HSA. Although ascorbic acid aided in warfarin release, leading to destabilization of HSA, ibuprofen demonstrated a stabilizing effect on releasing the anticoagulant drug through several noncovalent interactions, including hydrophobic, electrostatic, and hydrogen-bonding interactions with the protein. The calculated binding free energy and energy contribution of involved residues using the molecular mechanics-Poisson Boltzmann surface area (MM-PBSA) method, along with root mean square deviation (RMSD) values, protein gyration, and free energy surface (FES) mapping of the protein, provided valuable details on the nature of the interactions of each drug on the release of warfarin from HSA. These results can provide important information on the mechanisms of anticoagulant release that has not been revealed in molecular details previously.

Binding of levobupivacaine-loaded gold nanoparticles to human serum albumin: a simulated physiological study

Techniques such as Fourier transform infrared (FTIR), ultraviolet-visible (UV-vis) spectra, fluorescence, circular dichroism (CD) and spectroscopy were applied to elucidate the formation, structure and physicochemical properties of levobupivacaine-gold nanoparticle (LGN) binding to human serum albumin (HSA). Thermodynamic parameters (ΔG = -2.58 × 10⁴ J·mol^-1 , ΔS = -7.80 J·mol^-1 ·K^-1 , and ΔS = -2.82 × 10⁴ J·mol^-1 at 305 K) suggested one weak binding site on HSA, which was governed by van der Waals forces as well as hydrogen bonds. Moreover, the outcomes of UV-vis, CD, FTIR, synchronous and three-dimensional fluorescence suggested that the microenvironment of HSA had been changed with addition of LGN. Based on the results of fluorescence resonance energy transfer, a distance of 2.8 nm between the LGN and HSA was observed. This approach has potential value for illustrating the pharmacodynamics of LGN when in combination with transmembrane transport, biomolecular function effect, and other experiments.

Presence of Gold Nanoparticles in Cells Associated with the Cell-Killing Effect of Modulated Electro-Hyperthermia

The efficacy of gold nanoparticle (AuNP)-assisted radiofrequency (RF)-induced hyperthermia employing the Kanzius device remains controversial. Different from the Kanzius device, modulated electro-hyperthermia (mEHT) utilizes the capacitive-impedance coupled 13.56 MHz radiofrequency (RF) current and has been approved for clinical cancer treatment. In this study, we investigated the heating characteristics of spherical-, urchin-, and rod-like AuNPs of a similar 50 nm size upon exposure to a 13.56 MHz radiofrequency using the LabEHY-105CL, an in vivo mEHT device. We found that, regardless of the AuNPs' sphere-, urchin- or rod-like shape, purified gold nanoparticle solution would not promote heat generation. The temperature elevation during radiofrequency irradiation was solely attributed to the ionic background of the solution. The AuNPs present in the medium (≤25 ppm) showed no effect on selective cell killing of malignant cells, whereas the AuNPs incorporated in the cells diminished the cell selectivity as well as cell death and acted as protectors in mEHT cancer treatment. Our study suggested that (1) the temperature elevation induced by 50 nm AuNPs in the 13.56 MHz radiofrequency field was negligible and was shape-independent, and (2) the presence of AuNPs would alter the cell-killing effect of modulated electro-hyperthermia.