Mechanistic and Conformational Studies on the Interaction Between Myriocin and Human Serum Albumin by Fluorescence Spectroscopy and Molecular Docking

Exploring the binding characteristics of bovine serum albumin with CDK4/6 inhibitors Ribociclib: Multi-spectral analysis and molecular simulation studies

Ribociclib (RIB), a tyrosine kinase inhibitor, exhibits promising antitumor efficacy and controlled toxicity in HR+/HER2- breast cancer patients, which is closely related to the binding with plasma proteins. This study utilized a combination of spectroscopic techniques including UV spectroscopy, fluorescence spectroscopy, and circular dichroism (CD) as well as molecular docking and molecular dynamic simulation to clarify the binding mechanism between bovine serum albumin (BSA) and RIB. The findings demonstrated that RIB produced a 1:1 stoichiometric complex with BSA, which quenched BSA's fluorescence in the manner of the static quenching mechanism. Site labelling experiments pinpointed Site III on BSA as the primary binding site for RIB, a finding validated by molecular docking. Van der Waals forces and hydrogen bonding interactions as key drivers in the formation of RIB-BSA complexes, a conclusion supported by molecular docking. Molecular simulation studies suggested that the insertion of RIB into the hydrophobic cavity (Site III) of BSA induced subtle conformational changes in the BSA protein, and CD measurements confirmed alterations in BSA secondary structure content. Synchronous and three-dimensional fluorescence spectroscopy further demonstrated that RIB decreased the hydrophobicity of the microenvironment surrounding tyrosine and tryptophan residues. These findings offer valuable insights into the pharmacokinetics and structural modifications of RIB.

Deciphering the binding mechanism of gingerol molecules with plasma proteins: implications for drug delivery and therapeutic potential

Ginger is a highly valued herb, renowned globally for its rich content of phenolic compounds. It has been traditionally used to treat various health conditions such as cardiovascular diseases, digestive issues, migraines, Alzheimer's disease, tumor reduction and chronic inflammation. Despite its potential medicinal applications, the therapeutic effectiveness of ginger is hindered by its limited availability and low plasma concentration levels. In this study, we explored the interaction of ginger's primary phenolic compounds, specifically 6-gingerol (6 G), 8-gingerol (8 G) and 10-gingerol (10 G), with plasma proteins which are human serum albumin (HSA) and α-1-acid glycoprotein (AGP). These two plasma proteins significantly influence drug distribution and disposition as they are key binding sites for most drugs. Fluorescence emission spectra indicated strong binding of 6, 8 and 10 G with HSA, with binding constants of 2.03 ± 0.01 × 104 M-1, 4.20 ± 0.01 × 104 M-1 and 6.03 ± 0.01 × 106 M-1, respectively. However, the binding of gingerols with AGP was found to be negligible. Molecular displacement by site-specific probes and molecular docking analyses revealed that gingerols bind at the IIA domain, with stability provided by hydrogen bonds, van der Waals forces, conventional hydrogen bonds, carbon-hydrogen bonds, alkyl and Pi-alkyl interactions. Further, the partial unfolding of the protein was observed upon binding the gingerol compound with HSA. In addition, molecular dynamic simulations demonstrated that gingerols remained stable in the subdomain IIA over 100 ns. This stability, coupled with Molecular Mechanics Generalized Born Surface Area indicating free energies of -43.765, -57.504 and -66.69 kcal/mol for 6, 8 and 10 G, respectively, reinforces the robust binding potential of these compounds. Circular dichroism studies suggested that the interaction of gingerols leads to the minimal transformation of HSA secondary structure, with the pattern being 10 G > 8 G > 6 G, a finding further substantiated by root mean square deviation and root mean square fluctuation fluctuations. These results propose that HSA has a stronger affinity to gingerols than AGP, which could have significant implications on the therapeutic circulating levels of gingerols.Communicated by Ramaswamy H. Sarma.

In Vitro and In Silico Analysis of the Bindings between Legacy and Novel Per- and Polyfluoroalkyl Substances and Human Serum Albumin

Per- and polyfluoroalkyl substances (PFASs) are emerging contaminants of concern that can enter the human body through a variety of pathways and thereby cause harmful effects. Exposure of pregnant women to PFASs could even affect both the mother and the child. Human serum albumin (HSA) is considered to be the primary transport protein for a variety of substances in body fluids. It can be bound to different contaminants and might result in possible effects on human health. Yet, few studies are available on the binding affinity of legacy PFASs and their novel alternatives to HSA. In this study, the binding mechanisms of HSA to both legacy PFASs and their novel alternatives were investigated using fluorescence spectroscopy, together with further molecular docking. The results show that all the target PFASs were statically quenched against HSA with binding ratios of 1:1. The binding constants of long-chain PFASs and novel alternatives of perfluoroalkanesulfonic acids (PFSAs) were greater than 102, whereas those of short-chain PFASs alternatives and novel alternatives of perfluorocarboxylic acids (PFCAs) were less than 102. In general, the binding affinities of PFCAs on HSA were less than that of PFSAs, while the binding affinities of short-chain PFASs alternatives on HSA were smaller than those of long-chain PFASs and their novel alternatives. Therefore, bindings to HSA could be considered as an important influencing factor for the bioaccumulation of legacy and novel PFASs in the human body.

Comparative investigation on interaction between potent antimalarials and human serum albumin using multispectroscopic and computational approaches

This study performed a comparative investigation to explore the interaction mechanisms between two potential antimalarial compounds, JMI 346 and JMI 105, and human serum albumin (HSA), a vital carrier protein responsible for maintaining important biological functions. Our aim was to assess the pharmacological efficiency of these compounds while comprehensively analyzing their impact on the dynamic behavior and overall stability of the protein. A comprehensive array of multispectroscopic techniques, including UV-Vis. spectroscopy, steady-state fluorescence analysis, synchronous fluorescence spectroscopy, three-dimensional fluorescence and circular dichroism spectroscopy, docking studies, and molecular dynamics simulations, were performed to probe the intricate details of the interaction between the compounds and HSA. Our results revealed that both JMI 346 and JMI 105 exhibited promising pharmacological effectiveness within the context of malaria therapy. However, JMI 346 was found to exhibit a significantly higher affinity and only minor altered impact on HSA, suggesting a more favorable interaction with the protein on the dynamic behavior and overall stability of the protein in comparison to JMI 105. Further studies can build on these results to optimize the drug-protein interaction and enable the development of more potent and targeted antimalarial treatments.

Role of Polyanions and Surfactant Head Group in the Formation of Polymer-Colloid Nanocontainers

OBJECTIVES

This study was aimed at the investigation of the supramolecular systems based on cationic surfactants bearing cyclic head groups (imidazolium and pyrrolidinium) and polyanions (polyacrylic acid (PAA) and human serum albumin (HSA)), and factors governing their structural behavior to create functional nanosystems with controlled properties. Research hypothesis. Mixed PE-surfactant complexes based on oppositely charged species are characterized by multifactor behavior strongly affected by the nature of both components. It was expected that the transition from a single surfactant solution to an admixture with PE might provide synergetic effects on structural characteristics and functional activity. To test this assumption, the concentration thresholds of aggregation, dimensional and charge characteristics, and solubilization capacity of amphiphiles in the presence of PEs have been determined by tensiometry, fluorescence and UV-visible spectroscopy, and dynamic and electrophoretic light scattering.

RESULTS

The formation of mixed surfactant-PAA aggregates with a hydrodynamic diameter of 100-180 nm has been shown. Polyanion additives led to a decrease in the critical micelle concentration of surfactants by two orders of magnitude (from 1 mM to 0.01 mM). A gradual increase in the zeta potential of HAS-surfactant systems from negative to positive value indicates that the electrostatic mechanism contributes to the binding of components. Additionally, 3D and conventional fluorescence spectroscopy showed that imidazolium surfactant had little effect on HSA conformation, and component binding occurs due to hydrogen bonding and Van der Waals interactions through the tryptophan amino acid residue of the protein. Surfactant-polyanion nanostructures improve the solubility of lipophilic medicines such as Warfarin, Amphotericin B, and Meloxicam.

PERSPECTIVES

Surfactant-PE composition demonstrated beneficial solubilization activity and can be recommended for the construction of nanocontainers for hydrophobic drugs, with their efficacy tuned by the variation in surfactant head group and the nature of polyanions.

Comprehending binding features between ibrutinib and Human Alpha-1 acid glycoprotein: Combined experimental approaches and theoretical simulations

Human alpha-1 acidic glycoprotein (HAG) is one of the proteins widely present in the blood, and the level of HAG in patients with cancer and inflammation is significantly increased. As one of transport proteins in the blood, the ability of HAG to bind with a drug, especially alkaline drugs, affects significantly the drug content at the target site, which in turn affects the efficacy of the drug. In this study, the interaction mechanism between HAG and the first generation Bruton's tyrosine kinase (BTK) inhibitor namely ibrutinib was explored by a combination of multi-spectroscopic techniques and theoretical calculations. The findings revealed that the quenching and binding constants of the HAG-ibrutinib system both reduced as the temperature rose, demonstrating that ibrutinib quenched the intrinsic fluorescence of HAG in a static manner. It was confirmed that HAG and ibrutinib formed a 1:1 complex with moderate affinity due to the binding constant of around 10⁵ M^-1 and accompanied by Förster resonance energy transfer. It was verified by thermodynamic parameter analysis and competition assays as well as molecular simulation that the existence of hydrogen bonds, van der Waals forces, and hydrophobic forces in the complexation of HAG and ibrutinib.The findings from theoretical calculations including molecular docking and theoretical calculation simulation confirmed that ibrutinib bound to the barrel hydrophobic pocket of HAG with a binding energy of -41.9 kJ∙mol^-1, and the the binding constant of around 10⁵ M^-1 and the contribution of each residue in the complexation of ibrutinib and HAG. Additionally, it can be confirmed that metal ions affected the binding interaction of ibrutinib with HAG, among them, some promoted binding while others inhibited it.

Interactions between Human Serum Albumin and Sulfadimethoxine Determined Using Spectroscopy and Molecular Docking

Sulfonamides are widely used antibiotics in agricultural production. However, the potential threat of these drugs to human health has increased global concern. Human serum albumin (HSA) is the main reservoir and transporter of exogenous small molecules in humans. In this study, the interaction between sulfadimethoxine (SMT) and human serum albumin (HSA) was studied using spectroscopy and computer simulation. Our results showed that the hydrogen bonding and van der Waals forces drove SMT to enter the binding site I of HSA spontaneously and resulted in the fluorescence quenching of HSA. The stability of the HSA–SMT complex decreased with an increase in temperature. The binding of SMT to HSA induced alterations in the secondary structure of HSA, where the content of α-helix decreased from 61.0% of the free state to 59.0% of the compound state. The π–π, π–σ, and π–alkyl interactions between HSA and SMT were found to play important roles in maintaining the stability of the complex.

Multi-spectroscopic and molecular docking studies of human serum albumin interactions with sulfametoxydiazine and sulfamonomethoxine

Sulfonamides are a kind of antibiotics which have been widely used as feed additives for livestock and poultry. However, sulfa drugs have raised worldwide concerns because of their adverse impact on human health. In this study, two sulfonamides, sulfametoxydiazine (SMD) and sulfamonomethoxine (SMM), were selected to explore the binding modes with human serum albumin (HSA). The spectroscopic approaches revealed that SMD or SMM could spontaneously enter into the binding site I of HSA through hydrogen bond interactions and van der Waals forces, and that SMD exhibited much stronger binding affinity toward HSA than SMM at different temperatures (p < 0.01, n = 3). The binding constants for SMD-HSA and SMM-HSA were determined to be (8.297 ± 0.010) × 10⁴ L·mol^-1 and (1.178 ± 0.008) × 10⁴ L·mol^-1 at 298 K, respectively. The interaction of SMD or SMM to HSA induced microenvironmental and conformational changes in HSA, where SMD had a greater effect on the α-helix content of HSA. Results from molecular docking implied that the amino acid residues of HSA, such as Arg222, Ala291 and Leu238, played key roles in the sulfonamide-HSA binding process. Meanwhile, hydrogen bonds might be a key factor contributing to the binding affinity of sulfa drugs and HSA. Additionally, the combined use of SMD and SMM led to an obvious variation in K_a values of binary systems (p < 0.01, n = 3). These findings might be helpful to understand the biological effects of sulfonamides in humans.