Study on the Interactions Between Caffeoylquinic Acids With Bovine Serum Albumin: Spectroscopy, Antioxidant Activity, LC-MSn, and Molecular Docking Approach

A chondroitin sulfate purified from shark cartilage and bovine serum albumin interaction activity

Chondroitin sulfate (CS) was extracted and purified from shark cartilage, and its interaction with bovine serum albumin (BSA) were studied. The content of chondroitin sulfate in shark cartilage was 29.97 % using the 1,9-dimethyl-methylene blue method. The molecular weight of CS was determined to be 62.464 kDa by high-performance gel permeation chromatography. UV and FT-IR spectroscopy identified the characteristics of CS and its functional group information. NMR spectroscopy and disaccharide derivatization revealed that CS was predominantly composed of disulfated disaccharides, specifically ΔDi4,6S. Fluorescence quenching experiments indicated that the interaction between CS and BSA exhibited static quenching, with a binding site number of 1. The binding process was primarily mediated by van der Waals forces and hydrogen bonds. Furthermore, synchronous and 3D fluorescence spectroscopy demonstrated that CS had minimal impact on the polarity and hydrophobicity of the microenvironment surrounding Tyr and Trp residues. UV-vis absorption and circular dichroism (CD) spectroscopy demonstrated the altered structure of BSA. The molecular docking analysis revealed that CS formed hydrogen bonds and salt bridges with BSA, predominantly binding to the IIA substructure domain of BSA. Investigating the interaction between CS and BSA holds the potential for enhancing its applications in drug delivery and tissue engineering endeavors.

Impact of Sinapic Acid on Bovine Serum Albumin Thermal Stability

The thermal stability of bovine serum albumin (BSA) in Tris buffer, as well as the effect of sinapic acid (SA) on protein conformation were investigated via calorimetric (differential scanning microcalorimetry-μDSC), spectroscopic (dynamic light scattering-DLS; circular dichroism-CD), and molecular docking approaches. μDSC data revealed both the denaturation (endotherm) and aggregation (exotherm) of the protein, demonstrating the dual effect of SA on protein thermal stability. With an increase in ligand concentration, (i) protein denaturation shifts to a higher temperature (indicating native form stabilization), while (ii) the aggregation process shifts to a lower temperature (indicating enhanced reactivity of the denatured form). The stabilization effect of SA on the native structure of the protein was supported by CD results. High temperature (338 K) incubation induced protein unfolding and aggregation, and increasing the concentration of SA altered the size distribution of the protein population, as DLS measurements demonstrated. Complementary information offered by molecular docking allowed for the assessment of the ligand binding within the Sudlow's site I of the protein. The deeper insight into the SA-BSA interaction offered by the present study may serve in the clarification of ligand pharmacokinetics and pharmacodynamics, thus opening paths for future research and therapeutic applications.

Exploring the effect of surfactants on the interactions of manganese dioxide nanoparticles with biomolecules

Interactions of manganese dioxide nanoparticles (MnO2 NPs) with vital biomolecules namely deoxyribonucleic acid (DNA) and serum albumin (BSA) have been studied in association with different surfactants by using fluorescence (steady state, synchronous and 3D), UV-visible, resonance light scattering (RLS), dynamic light scattering (DLS), and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The esterase activity of serum albumin was tested in associations with MnO2 NPs and surfactants. The antioxidant potential of prepared NPs was also evaluated (DPPH method). Gel electrophoresis was carried out to analyze the effect of MnO2 NPs and surfactants on DNA. Presence of CTAB, Tween 20, DTAB and Tween 80 enhanced nanoparticle-protein binding. Tween 20 based nanoparticle systems showed long-term stability and biocompatibility. The quenching of BSA fluorescence emission in presence of MnO2 NPs alone and along with Tween 20 revealed stronger association of nanoparticles with proteins. Enhancement in the esterase activity (BSA) was observed in the presence of Tween 20. Furthermore, radical scavenging activity showed highest antioxidant potential in presence of Tween 20. The enthalpy and entropy assessment for protein-NPs association showed the predominance of Vander Waals interactions and hydrogen bonding. The synchronous fluorescence analysis highlighted the involvement of tryptophan (Trp) in the MnO2 NPs-protein interactions. The study evaluates the influence of surfactant on the associations of MnO2 NPs with the essential biomolecules. The findings can be crucially utilized in designing biocompatible MnO2 formulations for long term applications.Communicated by Ramaswamy H. Sarma.

Investigating the Protective Role of Biochaga Drug on Structural Changes of Bovine Serum Albumin in the Presence of Methyl tert-butyl Ether

BACKGROUND

The health benefits of natural products have a long history. Chaga (Inonotus obliques) is used in traditional medicine and is an essential antioxidant for protecting the body from oxidants. Reactive oxygen species (ROS) are produced routinely due to metabolic processes. However, environmental pollution factors such as methyl tert-butyl ether (MTBE) can increase oxidative stress in the human body. MTBE is widely used as a fuel oxygenator that can harm health. The widespread use of MTBE has posed significant threats to the environment by polluting environmental resources, including groundwater. This compound can accumulate in the bloodstream by inhaling polluted air, with a strong affinity for blood proteins. The primary mechanism of MTBE's harmful effects is ROS production. The use of antioxidants may help reduce MTBE oxidation conditions. The present study proposes that biochaga, as an antioxidant, can reduce MTBE damage in the bovine serum albumin (BSA) structure.

METHODS AND RESULTS

This study investigated the role of different concentrations of biochaga in the structural change of BSA in the presence of MTBE by biophysical methods such as UV-Vis, fluorescence, FTIR spectroscopy, DPPH radical inhibition method, aggregation test, and molecular docking. Research at the molecular level is critical to investigate the structural change of proteins by MTBE and the protective effect of the ideal dose (2.5 µg/ml) of biochaga.

CONCLUSION

the results of spectroscopic examinations showed that the concentration of 2.5 µg/ml of biochaga has the least destructive effect on the structure of BSA in the presence and absence of MTBE, and it can play as an antioxidant.

Antiviral Effect of Polyphenolic Substances in Geranium wilfordii Maxim against HSV-2 Infection Using in vitro and in silico Approaches

Background

Herpes simplex virus type 2 (HSV-2) infestation was the most widespread STD (sexually transmitted diseases) among humans and was the leading cause of infectious recurrent genital herpes. Existing therapies against HSV-2 did incompletely restrain the comeback of activated HSV-2 infestation. Geranium wilfordii Maxim had long been used as traditional Chinese medicine for treating the diseases owing to its anti-inflammatory and antiviral effects. Herein, the study was designed to investigate the antiviral activity of G.wilfordii and its potential effect in regulating the host's immune response.

Methods

To identify the stage of infection at which the compounds inhibited HSV-2, we performed virucidal, therapeutic, and prophylactic assays. The antiviral efficacy was evaluated by the analysis of viral components HSV-2 gD and VP16. The antiviral activities of these compounds were also evaluated by phenotypic analysis, such as cell proliferation and apoptosis. Molecular docking studies on candidate compounds were done to indicate binding interactions between the compounds and adopted compound targets.

Results

Quercetin, corilagin, and geraniin inhibited the replication of HSV-2, with geraniin showing greater TI. The obtained IC₅₀ value of quercetin was 204.7 μM and TI (IC₅₀/EC₅₀) was 5.1, whereas the obtained IC₅₀ value of corilagin was 118.0 μg/ml and TI was 4.05. Geraniin exhibited prominent antiviral activity with an IC₅₀ of 212.4 μM and an EC₅₀ of 18.37 μM, resulting in a therapeutic index (TI) of 11.56. Geraniin showed important in vitro virucidal activity through blocking viral attachment. Compared with the virus group, the apoptosis rates in quercetin-, corilagin-, and geraniin-treated groups were significantly decreased (p < 0.001).The expressions at the transcription genes of virus own replication key factors (including HSV-2 gD and VP16) and cytokines (including TBK1) of infected cells treated with quercetin, corilagin, and geraniin were inhibited. The in silico approaches demonstrated a high number of potential strong intermolecular interactions as hydrogen bonds between geraniin, corilagin, and the activity site of HSV-2 gD. Molecular docking studies demonstrated the effects of corilagin by targeting TBK1.

Conclusions

Together, these results highlighted the importance of G.wilfordii treatment in HSV-2 infection and underscored its therapeutic potential. However, additional in vitro and in vivo research was required to validate our findings.

The Study of Protein-Cyclitol Interactions

Investigation of interactions between the target protein molecule and ligand allows for an understanding of the nature of the molecular recognition, functions, and biological activity of protein–ligand complexation. In the present work, non-specific interactions between a model protein (Bovine Serum Albumin) and four cyclitols were investigated. D-sorbitol and adonitol represent the group of linear-structure cyclitols, while shikimic acid and D-(–)-quinic acid have cyclic-structure molecules. Various analytical methods, including chromatographic analysis (HPLC-MS/MS), electrophoretic analysis (SDS-PAGE), spectroscopic analysis (spectrofluorimetry, Fourier transform infrared spectroscopy, and Raman spectroscopy), and isothermal titration calorimetry (ITC), were applied for the description of protein–cyclitol interactions. Additionally, computational calculations were performed to predict the possible binding places. Kinetic studies allowed us to clarify interaction mechanisms that may take place during BSA and cyclitol interaction. The results allow us, among other things, to evaluate the impact of the cyclitol’s structure on the character of its interactions with the protein.

Investigating binding dynamics of trans resveratrol to HSA for an efficient displacement of aflatoxin B1 using spectroscopy and molecular simulation

Resveratrol is a polyphenol belonging to the class stilbenes. The active and stable form of resveratrol is trans-resveratrol. This polyphenol is bestowed with numerous biological properties. Aflatoxin B₁ is a hepato-carcinogen and mutagen that is produced by Aspergillus species. In this study, the interaction of trans-resveratrol with HSA followed by competitive dislodging of AFB₁ from HSA by trans-resveratrol has been investigated using spectroscopic studies. The UV-absorption studies revealed ground state complex formation between HSA and trans-resveratrol. Trans-resveratrol binds strongly to HSA with the binding constant of ~ 10⁷ M⁻¹ to a single binding site (n = 1.58), at 298.15 K. The Stern–Volmer quenching constant was calculated as 7.83 × 10⁴ M⁻¹ at 298.15 K, suggesting strong fluorescence quenching ability of trans-resveratrol. Site markers displacement assay projected subdomain IIA as the binding site of trans-resveratrol to HSA. The molecular docking approach envisages the amino acid residues involved in the formation of the binding pocket. As confirmed from the site marker displacement assays, both trans-resveratrol and AFB₁ binds to HSA in the same binding site, subdomain IIA. The study explores the ability of trans-resveratrol to displace AFB₁ from the HSA-AFB₁ complex, thereby affecting the toxicokinetic behavior of AFB₁ associated with AFB₁ exposure.

Discovery of Novel Tubulin Polymerization Inhibitors by Utilizing 3D-QSAR, Molecular Docking and Molecular Dynamics Simulation

Tubulin is a potential therapeutic target for cancer. Compounds inhibit the polymerization of tubulin or promote the polymerization of tubulin to interfere with the mitotic process of cells, resulting in...