Studying the interaction of drug/ligand with serum albumin

Multicomponent catalyst-free regioselective synthesis and binding studies of 3-aroyl-2-methylimidazo[1,2-a]pyrimidines with BSA using biophysical and computational techniques

A facile and environmentally benign protocol for regioselective synthesis of diversely substituted imidazo[1,2-a]pyrimidines 5a-h has been described via multicomponent reaction of unsymmetrical β-diketones 1, N-bromosuccinimide 2 and 2-aminopyrimidine 4 in DCM. The reaction proceeds through in situ formation of α-bromo-β-diketones 3 and their ensuing condensation with 2-aminopyrimidine without the need of any organic or inorganic catalyst. The structure of the regioisomeric product was characterized by 1H, 13C NMR, heteronuclear 2D NMR and HRMS studies. The present protocol offers several advantages such as avoidance of metal-based and toxic catalysts, broad substrate scope with respect to substitutions on β-diketones, operational simplicity, easy work-up and high yields. Computational molecular docking studies were carried out to examine the interaction of imidazo[1,2-a]pyrimidines with bovine serum albumin (BSA). Moreover, different spectroscopic approaches viz. UV-visible, steady-state fluorescence and competitive displacement assays were carried out to investigate the binding mechanisms of imidazo[1,2-a]pyrimidines (5c, 5e and 5h) with BSA. The results thus obtained revealed that imidazo[1,2-a]pyrimidines showed moderate binding with BSA through a static quenching mechanism and compound 5e had more affinity to bind in site I of BSA.

Molecular insight on conformational alterations and functional changes of acetylcholinesterase induced by an emerging environmental pollutant 6PPD-quinone

The emerging pollutant N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPD-quinone) has attracted broad attention because of its widespread presence and harmful impacts, including hepatotoxicity and neurotoxicity. Acetylcholinesterase (AChE) is commonly used as a classical biomarker for assessing toxicity in the nervous system. Here, the interaction mechanism between AChE and 6PPD-quinone was investigated using a combination of multispectral and computational approaches, including enzyme activity assay, fluorescence thermodynamic titration, circular dichroism (CD) spectroscopy, molecular dynamics (MD) simulation, computational alanine scanning (CAS), and free energy landscape (FEL) analysis, among others. The result indicates that 6PPD-quinone spontaneously binds into the active site of AChE, thereby competitively inhibiting enzyme's activity. The interaction is primarily facilitated by hydrogen bonds and van der Waals forces, exhibiting a binding constant (Kb) of 1.044 × 104 M-1 at 298 K. The introduction of 6PPD-quinone causes a reduction in the α-helix content of AChE, making the structure less stable and more relaxed. Furthermore, the FEL analysis of AChE revealed that, with the presence of 6PPD-quinone, the number of global minima of AChE increased from 2 to 2-3. Additionally, Molecular docking outcomes exhibit that 6PPD-quinone interacted with tyrosine (TYR) 337, TYR124, tryptophan (TRP) 86, serine (SER) 203, glycine (GLY) 120 and other residues of AChE. CAS analysis shows binding free energy changes (ΔΔGbinding) of TRP86, TYR337 were 5.17 and 2.57 kcal mol-1, respectively, highlighting their key roles in the binding process of 6PPD-quinone with AChE. The interactions of 6PPD-quinone with the TRP86 and TYR337 may be the reason for the decrease in AChE activity.

Formation of self-assembled polyelectrolyte complex derived from BSA and nanogels: a study to optimize processing parameters and preserve protein integrity

OBJECTIVE

The aim of this work was to identify, optimize, and use nondestructive process to develop nano-formulation using polyelectrolyte complexation (PEC) between polymeric nanocarrier and bovine serum albumin.

SIGNIFICANCE

Proteins are mostly degraded during preparation and loading into nano-carriers which hinders success in protein delivery.

METHOD

Herein, novel PEC consisting of model protein BSA and nanogels (NGs), were prepared to form self-assembled polyelectrolyte nanocomplexes (BSA/NGs-PEC). The BSA/NGs-PEC were obtained by mixing BSA and nanogels at various weight ratios (1:2, 1:4, 1:5, 1:6, 1:8, 1:10), pH values of solution (1.2, 4.0, 6.0), incubation time (2, 4, 6, 8 h), and stirring rate (without, 100, 200 rpm). The prepared PEC were evaluated for particle size (PS), polydispersity index (PDI), zeta potential (ZP), and percentage of complexation efficiency (%CE). To study insights into structural integrity and biological activity, the SDS-PAGE and esterase activity assay was performed on BSA released from final optimized formulation.

RESULTS

The optimized parameters were BSA/nanogels mixing ratios at 1:8, pH of complex-forming medium at 4.0, incubation time of 6 h, and stirring rate at 100 rpm. The SDS-PAGE and esterase activity assay revealed that the primary structure and bioactivity, respectively, of BSA was still intact.

CONCLUSION

The results suggest that current scheme for optimization has considerable potential for creating protein-based delivery system by using PEC via electrostatic interaction.

Comparison on the conformation folding and structure change of serum albumin induced by methyl parathion and its metabolite p-nitrophenol

Residues of organophosphorus pesticides (OPPs) and their metabolites pose potential risks to the environment and human health. In the work, multiple spectroscopy, atomic force microscope and computational simulations were utilized to compare the interaction between methyl parathion (MP) and its metabolite p-nitrophenol (PNP) with human serum albumin (HSA). The results showed that both MP and PNP spontaneously formed complexes with HSA predominantly facilitated by hydrogen bonds and van der Waals forces, following static quenching mechanisms. The binding constant of PNP (15.16 ± 0.10 × 104 L mol-1) with HSA was nearly 5 times larger than that of MP (3.58 ± 0.09 × 104 L mol-1), suggesting PNP had a stronger affinity with HSA, which was consistent with density functional theory (DFT) calculation. Molecular docking revealed that the binding energy of PNP (-4.54 kcal mol-1) was lower than that of MP (-4.07 kcal mol-1), which potentially contributed a longer in vivo half-life of PNP and greater potential harm. Moreover, synchronous, 3D, FTIR and CD spectroscopy analyses indicated that the binding of MP and PNP to HSA significantly altered the microenvironment of amino acid residues and the secondary structure of HSA. Molecular dynamics simulations further demonstrated these findings. The study provides insights on the interaction between the pesticide MP and its metabolite PNP with HSA, which help understand the impact of pesticide residues on the food safety and environmental protection at the molecular level.

Molecular interaction study of L-Ornithine with bovine serum albumin using spectroscopic and molecular docking methods

Activates the pituitary gland, leading to increased secretion of growth hormone. This activation plays a crucial role in growth, metabolism, and tissue repair. Bovine serum albumin, a well-studied protein, demonstrates the interaction between proteins-ligands and transports various compounds in the bloodstream. This study elucidates the molecular interactions between L-ornithine and BSA through spectroscopic analysis, identifying binding modes, constants, and structural changes. Molecular docking techniques are employed to correlate with experimental data from fluorescence and UV spectroscopy analyses.The study uses Fourier transform infrared spectroscopy, UV-Visible spectroscopy, fluorescence spectroscopy, circular dichroism spectroscopy and molecular docking to analyze the interaction between bovine serum albumin and L-ornithine, providing thermodynamic parameters for understanding the protein structure and its binding.The interactions between L-ornithine and bovine serum albumin (BSA) were characterized using UV-visible spectroscopy, which demonstrated a hyperchromic shift. Fluorescence spectroscopy revealed that L-ornithine quenches the intrinsic fluorescence of both BSA and human serum albumin (HSA) via a static quenching mechanism, resulting in the formation of stable BSA-L-ornithine and HSA-L-ornithine complexes. Furthermore, Fourier-transform infrared (FTIR) and circular dichroism (CD) spectroscopy indicated a decrease in the secondary structure of the proteins, as evidenced by shifts in the amide II band and a concomitant reduction in α-helix content. Molecular docking studies suggested that L-ornithine binds to BSA within subdomain II. Collectively, these findings provide valuable insights into the metabolic pathways of L-ornithine and its potential pharmacological relevance. The study involves more precise information which revealing the insight of L-ornithine bioavailability. The finding enhances our understanding of interaction with potential implications for drug delivery.

Fluorescence phasor analysis: basic principles and biophysical applications

Fluorescence is one of the most widely used techniques in biological sciences. Its exceptional sensitivity and versatility make it a tool of first choice for quantitative studies in biophysics. The concept of phasors, originally introduced by Charles Steinmetz in the late nineteenth century for analyzing alternating current circuits, has since found applications across diverse disciplines, including fluorescence spectroscopy. The main idea behind fluorescence phasors was posited by Gregorio Weber in 1981. By analyzing the complementary nature of pulse and phase fluorometry data, he shows that two magnitudes-denoted as G and S-derived from the frequency-domain fluorescence measurements correspond to the real and imaginary parts of the Fourier transform of the fluorescence intensity in the time domain. This review provides a historical perspective on how the concept of phasors originates and how it integrates into fluorescence spectroscopy. We discuss their fundamental algebraic properties, which enable intuitive model-free analysis of fluorescence data despite the complexity of the underlying phenomena. Some applications in molecular biophysics illustrate the power of this approach in studying diverse phenomena, including protein folding, protein interactions, phase transitions in lipid mixtures, and formation of high-order structures in nucleic acids.

The Molecular Recognition of Lurasidone by Human Serum Albumin: A Combined Experimental and Computational Approach

Lurasidone (LUR) is an antipsychotic drug whose interaction with human serum albumin (HSA) plays a crucial role in its pharmacokinetic and pharmacodynamic properties. A thorough understanding of LUR's binding mechanism to HSA is crucial for predicting its transport, distribution, and potential drug interactions.

METHODS

The interaction between LUR and HSA was investigated using fluorescence and circular dichroism (CD) spectroscopy, followed by molecular docking simulations. Binding characteristics were analyzed through quenching mechanisms, thermodynamic parameters, and competitive site marker experiments.

RESULTS

This study revealed a systematic decrease in HSA fluorescence intensity with increasing LUR concentration, indicating a static quenching mechanism driven by non-fluorescent complex formation. Binding constants suggest enhanced complex stability at higher temperatures, with thermodynamic analysis confirming an endothermic, hydrophobic interaction. Competitive site marker assays and synchronous fluorescence spectra confirmed that LUR primarily binds to site I (subdomain IIA) near tryptophan residues. Conformational changes in HSA, observed as a decrease in α-helix content, further demonstrate the structural impact of LUR binding.

CONCLUSIONS

These findings offer key insights into the molecular interactions between LUR and HSA, enhancing our understanding of LUR's pharmacokinetics and its potential interactions with other drugs. Understanding these binding characteristics can aid in optimizing LUR's clinical application and predicting possible interactions with other biomolecules.

Spectroscopic and molecular docking studies on binding interactions of camptothecin drugs with bovine serum albumin

This study investigates the binding interactions between bovine serum albumin (BSA) and camptothecin (CPT) drugs (camptothecin, 10-hydroxycamptothecin, topotecan, and irinotecan) using UV-Vis spectroscopy, fluorescence spectroscopy, three-dimensional fluorescence spectroscopy, and molecular docking techniques. The fluorescence quenching of BSA by CPT drugs follows a static mechanism, with binding constants (Kb) ranging from 4.23 × 103 M- 1 (CPT) to 101.30 × 103 M- 1 (irinotecan), demonstrating significant drug binding selectivity. Thermodynamic analysis reveals distinct interaction mechanisms: topotecan binding is driven by hydrogen bonding (ΔH = - 10.96 kJ·mol- 1) and hydrophobic interactions (ΔS = 0.066 kJ·mol- 1·K- 1), while irinotecan exhibits stronger binding dominated by electrostatic forces (ΔH = - 86.77 kJ·mol- 1) with significant entropy loss (ΔS = - 0.161 kJ·mol- 1·K- 1). Molecular docking confirms preferential binding at Sudlow site I of BSA, with hydrophobic interactions and hydrogen bonding as the primary driving forces. These findings provide a comprehensive understanding of CPT-BSA interactions, offering valuable insights for the design of albumin-based drug delivery systems with optimized pharmacokinetic profiles.

Explore the toxicological mechanism of 6PPD-Q on human health through a novel perspective: The interaction between lactate dehydrogenase and 6PPD-Q

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q), an oxidative derivative of tire anti-degradant, has been linked to mortality in coho salmon (Oncorhynchus kisutch) and has exhibited potential human toxicity. Hence, exploring how 6PPD-Q interacts with biomacromolecules like enzymes is indispensable to assess its human toxicity and elucidate its mechanism of action. This investigation aims to explore the impact of 6PPD-Q on lactate dehydrogenase (LDH) through various methods. The findings indicate that 6PPD-Q can spontaneously embed in the coenzyme site of LDH and obviously change the biological activity of LDH by non-competitive inhibition. Simultaneously, this inhibitory effect is concentration-dependent. 6PPD-Q can affect both the level of LDH and the transcription of Ldha in AML-12 cells. Hydrogen bonding and van der Waals forces serve as the primary driving forces in LDH-6PPD-Q combination process. The apparent binding constant (Ka) value is (9.773 ± 0.699) × 103 L/mol (298 K). The presence of 6PPD-Q alters the conformation of LDH and decreases its structural stability. Moreover, the results of molecular docking indicate that the interaction of 6PPD-Q with Asp51 and Arg98 of LDH may be the reason that 6PPD-Q inhibits the biological activity of LDH. Meanwhile, the energy decomposition of residue analyses for LDH-6PPD-Q formation further highlight the energy contribution of Asp51 and Arg98 in this combination process.

An Investigation into Substitution-Kinetics, Biomolecular Responses and Multimodal Anticancer Potential of a Dihalide Pd(II) Complex

This study addresses a novel palladium dihalide complex, cis-[Pd(PCAH)Cl₂] (C1), as a promising anticancer agent. XRD analysis reveals a deformed square planar geometry stabilized by hydrogen bonds and π•••π interactions. The M-Cl bonds in C1 demonstrate susceptibility to nucleophilic substitution by 2,2'-bipyridine (Bpy), with kinetic parameters evaluated using spectrophotometry. Fluorometric and spectrophotometric investigations demonstrate that C1 binds to CT DNA and protein with an avidity of around 105 M-1. The interaction with DNA is multifaceted, employing covalent bonding and intercalation, as supported by viscosity measurements. Fluorescence lifetime experiments illustrate that C1 produces static dampening of BSA fluorescence, implying structural adjustments near the tryptophan residue, further corroborated by spectroscopic analyses. The pair's (BSA and C1) FRET distance has also been computed. In vitro cytotoxicity tests suggest that C1 selectively suppresses the growth of breast carcinoma, MDA-MB-231 with IC50=20±2.64 μM, while showing minimal effects on non-cancerous HEK-293 cells. The mechanism of action includes the creation of ROS, leading to mitochondrial apoptosis, as evidenced by various assays, including annexin-V-FITC/PI labeling. Overall, complex C1 exhibits encouraging promise as a selective anticancer drug with a ROS-triggered apoptotic mechanism, particularly effective against breast carcinoma MDA-MB-231 cells.

Isolation of Biomolecules Using MXenes

Biomolecule isolation is a crucial process in diverse biomedical and biochemical applications, including diagnostics, therapeutics, research, and manufacturing. Recently, MXenes, a novel class of two-dimensional nanomaterials, have emerged as promising adsorbents for this purpose due to their unique physicochemical properties. These biocompatible and antibacterial nanomaterials feature a high aspect ratio, excellent conductivity, and versatile surface chemistry. This timely review explores the potential of MXenes for isolating a wide range of biomolecules, such as proteins, nucleic acids, and small molecules, while highlighting key future research trends and innovative applications poised to transform the field. This review provides an in-depth discussion of various synthesis methods and functionalization techniques that enhance the specificity and efficiency of MXenes in biomolecule isolation. In addition, the mechanisms by which MXenes interact with biomolecules are elucidated, offering insights into their selective adsorption and customized separation capabilities. This review also addresses recent advancements, identifies existing challenges, and examines emerging trends that may drive the next wave of innovation in this rapidly evolving area.

Study on interaction with high-abundant blood proteins and identification of low-abundant proteins to 5-phenyl-1-(p-tolyl)-1 H-1,2,3-triazole by serum proteomics

In this study, a comprehensive investigation was undertaken to elucidate a simple triazole compound, 5-phenyl-1-(p-tolyl)-1 H-1,2,3-triazole (PPTT), its interactions with high-abundant proteins and identification of low-abundant proteins by serum proteomics. Employing a combination of spectroscopic techniques and computational chemistry, the interactions between PPTT and three high-abundance blood globular proteins, namely human serum albumin (HSA), human immunoglobulin G (HIgG), and hemoglobin (BHb), were explored, thereby ascertaining their binding constants and thermodynamic parameters at the molecular level. Subsequently, based on the differential proteomics, utilizing two-dimensional gel electrophoresis (2-DE) in conjunction with matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS), the research team isolated and identified differentially expressed low-abundance proteins in human blood serum samples following exposure to PPTT. The results showed that there were twenty highly expressed proteins identified from blood serum samples intervened by PPTT. Combining bioinformatics techniques, these proteins were classified, providing preliminary insights like preproprotein or precursors inhibiting the activity of elastase, defending and regulating the immune system, carrying lipid, and other functions into their biological functionalities. One of the differential proteins, apolipoprotein A-1 (ApoA-1) protein, was selected as a possible target to explore the mechanism of action of PPTT intervention on the related signaling pathways involved in human hepatocellular carcinomas(Hep G2) cells. These research findings offer scientifically sound guidance for further in-depth exploration, development, and application of the 1,2,3-triazole compound.

Nonlinear van't Hoff Behavior in the Interaction of Two Water-Soluble Porphyrins with Bovine Serum Albumin (BSA)

Thermodynamic analysis of the binding process of water-soluble negatively charged meso-tetrakis(p-sulfonatophenyl) (TPPS4) and positively charged meso-tetrakis(4-methylpyridyl) (TMPyP) porphyrins with bovine serum albumin (BSA) at different temperatures was carried out based on the data of BSA quenching fluorescence by porphyrins. The comparison of binding constants (K b) shows that negatively charged TPPS4 possesses higher affinity to BSA than positively charged TMPyP. Thermodynamic characteristics of the binding process were obtained in accordance with the van't Hoff theory by processing nonlinear dependences of ln K b on inverse absolute temperature within the framework of two models: taking into account the dependence or independence of the change in the standard heat capacity (ΔC 0) on temperature. A comparison of thermodynamic characteristics with the data obtained from the Förster fluorescence quenching theory and with literature data leads to the conclusion that TPPS4 is bound to the Sudlow I site (subdomain IIA), while TMPyP is bound to the Heme site (between the subdomains IA and IB). The analysis of ΔC 0 changes with temperature demonstrates that binding of TPPS4 promotes hydration of nonpolar groups in the protein, which increases with the increase of temperature, while binding of TMPyP decreases the hydration of polar groups of the protein, the effect increasing with rising temperature. The obtained information may be useful for elucidating the mechanisms of interaction of porphyrins with albumins and the effect of this interaction upon the effectiveness of porphyrins in photodynamic therapy and in fluorescence diagnostics of cancer.

Anti-Amyloid Aggregation and Anti-Hyperglycemic Activities of Novel Ruthenium Uracil Schiff Base Compounds

The formation and characterization of new diamagnetic ruthenium uracil mono-imine compounds: [(η6-p-cymene)RuII(L)Cl][BF4] (L=H2urpda=5-((pyridin-2-yl)methyleneamino)-6-aminouracil) for 1, urdpy=6-amino-1,3-dimethyl-5-((pyridin-2-ylmethylene)amino)uracil) for 2 or urqda=5-((quinolin-2-yl)methyleneamino)-6-aminouracil) for 3); cis-[Ru(bipy)2(urpy)](BF4)2 (4) (urpy=5-((pyridin-2-yl)methyleneamino)uracil) and cis-[Ru(bipy)2(dapd)] (5) (H2dadp=5,6-diaminouracil) are described. A ruthenium(IV) uracil Schiff base compound, trans-[Ru(urpda)(PPh3)Cl2] (6) was also formed. Various physicochemical techniques were utilized to characterize the novel ruthenium compounds. Similarly, the stabilities of 1-3 and 6 monitored in chloro-containing and the non-coordinating solvent, dichloromethane show that they are kinetically inert, whereas, in a high nucleophilic environment, the chloride co-ligands of these ruthenium complexes were rapidly substituted by DMSO. In contrast, the substitution of the labile co-ligands for these ruthenium complexes by DMSO molecules in a high chloride content was suppressed. Solution chemical reactivities of the different ruthenium complexes were rationalized by density functional theory computations. Furthermore, the binding affinities and strengths between BSA and the respective ruthenium complexes were monitored using fluorescence spectroscopy. In addition, the in vitro anti-diabetic activities of the novel metal complexes were assessed in selected skeletal muscle and liver cell lines.

Computational Analysis of Interactions Between Drugs and Human Serum Albumin

Drug molecules exist as complexed with serum proteins such as human serum albumin (HSA) and/or unbound free form in the blood circulation. Drugs can be effective only when they are free. Thus, it is important to understand aspects that are important for interaction between drugs and interacting proteins. In this study, interactions among 2990 FDA approved drugs and HSA were computational analyzed to unravel principles that are critical for drug-HSA interactions. Docking results showed that drugs have higher affinity toward cavity-1 (C1) than cavity-2 (C2). A total of 1131 drug molecules have docking score greater than 60 while 768 molecules have docking score greater than 60 when they are docked in C2. In addition, three solvent channels have potential to direct solvent to C1 cavity while C2 does not have any effective channel. The post MD analyses demonstrated that drugs are making polar interactions with basic amino acids in the binding cavities. Verbscoside and ceftazidime both have stable low RMSD values throughout MD simulation with 2 Å on average in C1 cavity. The ligand RMSD shows less stability for verbscoside, which is around 4 Å when it is in complex with HSA in C1. The individual contribution of the residues K192, K196, R215, and R254 to ceftazidime are -1.92 ± 0.18, -3.09 ± 0.09, -2.17 ± 0.17, and - 2.32 ± 0.098, respectively. These residues contribute the binding energy of the verbscoside by -6.06 ± 0.08, -2.10 ± 0.06, and - 1.57 ± 0.03 kcal/mol individually in C1 cavity. C2 is making polar interactions with drug via R469, K472, and K488 residues and their contribution to the two drugs are -3.13 ± 0.21 kcal/mol for R469, -1.94 ± 0.18 kcal/mol for K472, and -1.96 ± 0.11 kcal/mol for K488 to total binding energy of ceftazidime. The binding energy of verbscoside is 57.17 ± 7.00 kcal/mol and Arg-407 has the highest contribution this bind energy individually with -4.29 ± 0.12 kcal/mol. Drugs with hydrogen bond donor/acceptor chemical adducts such as verbscoside involve higher hydrogen bond formation in C1 pocket. Ceftazidime makes interaction with HSA toward hydrophobic residues, L384, L404, L487, and L488 in the C2 cavity.

Conformational alterations and functional changes of pepsin induced by a novel food supplement tetrahydrocurcumin: Multispectral techniques and computer simulations

Tetrahydrocurcumin (THC), as a novel food supplement, has generated significant interests for its potential impact on health and nutrition. Pepsin serves as the primary enzyme involved in the digestive mechanism. This research investigated the conformational and functional alterations of pepsin induced by THC using multispectral techniques and computer simulations. The results showed that THC enters the cavity of pepsin, in which hydrophobic forces play a major role. The binding constant is 1.044 × 104 M-1 at 310 K. The upregulation or downregulation effect of THC on pepsin activity depends on its concentration. Molecular docking outcomes indicated that THC was encapsulated by various amino acids and established H-bonds with Tyr189 and Ser294, revealing that hydrogen bonds also contribute to maintaining the stability of THC-pepsin complex. In addition, the altered activity of pepsin may be related to the interaction between THC and the amino acids at the active site (Asp32) according to energy contribution results. 3D fluorescence spectroscopy, CD spectra and molecular dynamic simulations show that THC causes conformational changes in pepsin. The existence of THC makes pepsin structure to be less dense, leading to the decrease of energy traps. This suggests that pepsin becomes conformationally more suitable to bind to THC.

Controlled Delivery of Paclitaxel via Stable Synthetic Protein Nanoparticles

Despite decades of intense research, glioma remains a disease for which no adequate clinical treatment exists. Given the ongoing therapeutic failures of conventional treatment approaches, nanomedicine may offer alternative options because it can increase the bioavailability of drugs and alter their pharmacokinetics. Here, a new type of synthetic protein nanoparticles (SPNPs) is reported that allow for effective loading and controlled release of the potent cancer drug, paclitaxel (PTX) - a drug that so far has been unsuccessful in glioma treatment due to hydrophobicity, low solubility, and associated delivery challenges. SPNPs are prepared by electrohydrodynamic (EHD) jetting of dilute solutions of PTX-loaded albumin made by high-pressure homogenization. After EHD jetting, PTX SPNPs possess a dry diameter of 165 ± 44 nm, hydrated diameter of 297 ± 102 nm, and a zeta potential of -19 ± 8 mV in water. For the SPNP formulation with a total PTX loading of 9.4%, the loading efficiency is 94%, and controlled release of PTX is observed over two weeks (6% burst release). PTX SPNPs are more potent (68% lethality) than free PTX (45% lethality using 0.2% dimethyl sulfoxide). PTX SPNPs in combination with IR show a significant survival benefit in glioma-bearing mouse models, avoid adverse liver toxicity, and maintain a normal brain architecture. Immunohistochemistry reveals a dramatic tumor size reduction including 40% long-term survivors without discernible signs of tumor. Using flexibly engineered SPNPs, this work outlines an efficient strategy for the delivery of hydrophobic drugs that are otherwise notoriously hard to deliver.

4-Methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP) exposure induces hepatotoxicity and nephrotoxicity - role of oxidative stress, mitochondrial dysfunction and pathways of cytotoxicity

Objective

Bisphenol A (BPA) is a ubiquitous pollutant worldwide and 4-Methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP) is considered a major active metabolite of BPA with a wide range of potent toxicological properties. However, its adverse outcome pathway (AOP) on the hepatic and renal system has not yet been explored.

Methods

Hence, the current study evaluated its effect on cell survival, oxidative stress, and apoptosis. In addition, the influence of signalling pathways on cytotoxicity and ROS generating enzymes (NOX2 and XO) on oxidative stress was explored by siRNA knockdown experiments. Further, its molecular interaction with SOD, CAT, and HSA (molecular docking and dynamics) was evaluated and validated with spectroscopy (fluorescence and FTIR) based methods.

Results

The outcome indicates that MBP exposure dose dependently increased the cytotoxic response, oxidative stress, and apoptosis in both hepatocytes and kidney cells. Further, MAPK signalling pathways and oxidative stress influenced the overall cytotoxic response in both cells. In addition, the stimulatory (NOX2 and XO) and inhibitory (SOD and CAT) effects of MBP were observed, along with a robust interaction with HSA.

Conclusions

The overall observation illustrates that MBP exposure adversely impacts hepatic and renal cells through oxidative stress and relevant molecular pathways which may connect the missing links during risk assessment of BPA.

Protein Nanospheres and Nanofibers Prepared by Ice-Templating for the Controlled Release of Hydrophobic Drugs

Protein scaffolds play a vital role in drug delivery systems. However, few research studies have been focused on loading hydrophobic drugs on protein scaffolds in biomedical fields. Here, we report on the development of protein microspheres and nanofibers by a simple ice-templating approach and their use as scaffolds for the controlled release of hydrophobic drugs, with bovine serum albumin (BSA) as the model protein and curcumin as the model hydrophobic drug. The BSA scaffolds display the unique nanofibrous and microspherical structures. This is a surprising discovery because there has been no report on the formation of microspheres via simple ice-templating of solutions or suspensions. To further understand the formation of microspheres by this approach, lysozyme, papain, and their composites with BSA are also studied. It is speculated that nanoparticles are first formed in aqueous BSA solution, attributed to the overlapping of hydration layers and autoassembly of inner hydrophobic cores of BSA globular molecules. Nanoprecipitation and soaking evaporation approaches are then used to load curcumin into the BSA scaffolds, followed by cross-linking with glutaraldehyde vapor to improve stability in an aqueous medium. The controlled release of curcumin is demonstrated, paving the way for various hydrophobic drugs loaded into this biodegradable and nonimmunogenic protein scaffold for potential treatments of diverse diseases.

Novel thiazole-based cyanoacrylamide derivatives: DNA cleavage, DNA/BSA binding properties and their anticancer behaviour against colon and breast cancer cells

A novel series of 2-cyano-3-(pyrazol-4-yl)-N-(thiazol-2-yl)acrylamide derivatives (3a-f) were synthesized using Knoevenagel condensation and characterized using various spectral tools. The weak nuclease activity of compounds (3a-f) against pBR322 plasmid DNA was greatly enhanced by irradiation at 365 nm. Compounds 3b and 3c, incorporating thienyl and pyridyl moieties, respectively, exhibited the utmost nuclease activity in degrading pBR322 plasmid DNA through singlet oxygen and superoxide free radicals' species. Furthermore, compounds 3b and 3c affinities towards calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) were investigated using UV-Vis and fluorescence spectroscopic analysis. They revealed good binding characteristics towards CT-DNA with Kb values of 6.68 × 104 M-1 and 1.19 × 104 M-1 for 3b and 3c, respectively. In addition, compounds 3b and 3c ability to release free radicals on radiation were targeted to be used as cytotoxic compounds in vitro for colon (HCT116) and breast cancer (MDA-MB-231) cells. A significant reduction in the cell viability on illumination at 365 nm was observed, with IC50 values of 23 and 25 µM against HCT116 cells, and 30 and 9 µM against MDA-MB-231 cells for compounds 3b and 3c, respectively. In conclusion, compounds 3b and 3c exhibited remarkable DNA cleavage and cytotoxic activity on illumination at 365 nm which might be associated with free radicals' production in addition to having a good affinity for interacting with CT-DNA and BSA.

Exploring the therapeutic potential of rutin through investigating its inhibitory mechanism on lactate dehydrogenase: Multi-spectral methods and computer simulation

Lactate dehydrogenase (LDH), a crucial enzyme in anaerobic glycolysis, plays a pivotal role in the energy metabolism of tumor cells, positioning it as a promising target for tumor treatment. Rutin, a plant-based flavonoid, offers benefits like antioxidant, antiapoptotic, and antineoplastic effects. This study employed diverse experiments to investigate the inhibitory mechanism of rutin on LDH through a binding perspective. The outcomes revealed that rutin underwent spontaneous binding within the coenzyme binding site of LDH, leading to the formation of a stable binary complex driven by hydrophobic forces, with hydrogen bonds also contributing significantly to sustaining the stability of the LDH-rutin complex. The binding constant (Ka) for the LDH-rutin system was 2.692 ± 0.015 × 104 M-1 at 298 K. Furthermore, rutin induced the alterations in the secondary structure conformation of LDH, characterized by a decrease in α-helix and an increase in antiparallel and parallel β-sheet, and β-turn. Rutin augmented the stability of coenzyme binding to LDH, which could potentially hinder the conversion process among coenzymes. Specifically, Arg98 in the active site loop of LDH provided essential binding energy contribution in the binding process. These outcomes might explain the dose-dependent inhibition of the catalytic activity of LDH by rutin. Interestingly, both the food additives ascorbic acid and tetrahydrocurcumin could reduce the binding stability of LDH and rutin. Meanwhile, these food additives did not produce positive synergism or antagonism on the rutin binding to LDH. Overall, this research could offer a unique insight into the therapeutic potential and medicinal worth of rutin.

The potential impact of 6PPD and its oxidation product 6PPD-quinone on human health: A case study on their interaction with human serum albumin

6PPD and its oxidation product, 6PPD-quinone have garnered widespread attention due to their adverse effects on aquatic ecosystems and human health, and are recognized as emerging pollutants. In this study, we investigated the interaction mechanism between 6PPD/6PPD-quinone and human serum albumin (HSA) through various experiments. Experimental findings reveal that the IC50 values of 6PPD-quinone and 6PPD against HEK293T cells were 11.78 and 40.04 μM, respectively. Additionally, the cytotoxicity of these compounds was regulated by HSA, displaying an inverse correlation with their binding affinity to HSA. Furthermore, 6PPD/6PPD-quinone can spontaneously insert into site I on HSA, forming a binary complex that induces changes in the secondary structure of HSA. However, their effects on the esterase-like activity of HSA exhibit a dichotomy. While 6PPD activates the esterase-like activity of HSA, 6PPD-quinone inhibits it. Molecular docking analyses reveal that both 6PPD and 6PPD-quinone interact with many amino acid residues on HSA, including TRP214, ARG222, ARG218, ALA291, PHE211. The π electrons on the benzene rings of 6PPD/6PPD-quinone play pivotal roles in maintaining the stability of complexes. Moreover, the stronger binding affinity observed between 6PPD and HSA compared to 6PPD-quinone, may be attributed to the larger negative surface potential of 6PPD.

Binding studies of promethazine and its metabolites with human serum albumin by high-performance affinity chromatography and molecular docking in the presence of codeine

"Purple Drank", a soft drink containing promethazine (PMZ) and codeine (COD), has gained global popularity for its hallucinogenic effects. Consuming large amounts of this combination can lead to potentially fatal events. The binding of these drugs to plasma proteins can exacerbate the issue by increasing the risk of drug interactions, side effects, and/or toxicity. Herein, the binding affinity to human serum albumin (HSA) of PMZ and its primary metabolites [N-desmethyl promethazine (DMPMZ) and promethazine sulphoxide (PMZSO)], along with COD, was investigated by high-performance affinity chromatography (HPAC) though zonal approach. PMZ and its metabolites exhibited a notable binding affinity for HSA (%b values higher than 80%), while COD exhibited a %b value of 65%. To discern the specific sites of HSA to which these compounds were bound, displacement experiments were performed using warfarin and (S)-ibuprofen as probes for sites I and II, respectively, which revealed that all analytes were bound to both sites. Molecular docking studies corroborated the experimental results, reinforcing the insights gained from the empirical data. The in silico data also suggested that competition between PMZ and its metabolites with COD can occur in both sites of HSA, but mainly in site II. As the target compounds are chiral, the enantioselectivity for HSA binding was also explored, showing that the binding for these compounds was not enantioselective.

Exploring the interaction of a potent anti-cancer drug Selumetinib with bovine serum albumin: Spectral and computational attributes

The binding of drugs to plasma proteins determines its fate within the physiological system, hence profound understanding of its interaction within the bloodstream is important to understand its pharmacodynamics and pharmacokinetics and thereby its therapeutic potential. In this regard, our work delineates the mechanism of interaction of Selumetinib (SEL), a potent anti-cancer drug showing excellent effect against multiple solid tumors, with plasma protein bovine serum albumin (BSA), using methods such as absorption, steady-state fluorescence, time-resolved, fluorescence resonance energy transfer, Fourier transform infrared spectra (FTIR), circular dichroism (CD), synchronous and 3D-fluorescence, salt fluorescence, molecular docking and molecular dynamic simulations. The BSA fluorescence intensity was quenched with increasing concentration of SEL which indicates interactions of SEL with BSA. Stern-Volmer quenching analysis and lifetime studies indicate the involvement of dynamic quenching. However, some contributions from the static quenching mechanism could not be ruled out unambiguously. The association constant was found to be 5.34 × 105 M-1 and it has a single binding site. The Förster distance (r) indicated probable energy transmission between the BSA and SEL. The positive entropy changes and enthalpy change indicate that the main interacting forces are hydrophobic forces, also evidenced by the results of molecular modeling studies. Conformation change in protein framework was revealed from FTIR, synchronous and 3D fluorescence and CD studies. Competitive binding experiments as well as docking studies suggest that SEL attaches itself to site I (subdomain IIA) of BSA where warfarin binds. Molecular dynamic simulations indicate the stability of the SEL-BSA complex. The association energy between BSA and SEL is affected in the presence of different metals differently.

In vitro investigation of the binding characteristics of dacomitinib to human α 1-acid glycoprotein: Multispectral and computational modeling

Dacomitinib is a highly selective second-generation tyrosine kinase inhibitor that can irreversibly bind to tyrosine kinase and is mainly used in the treatment of lung cancer. The binding characteristics of dacomitinib with human α 1-acid glycoprotein (HAG) were analyzed by multispectral and computational simulation techniques. The fluorescence spectra showed that dacomitinib can quench the fluorescence of HAG by forming the HAG-dacomitinib complex with a molar ratio of 1:1 (static quenching). At the temperature similar to that of the human body, the affinity of dacomitinib to HAG (8.95 × 106 M-1) was much greater than that to BSA (3.39 × 104 M-1), indicating that dacomitinib will give priority to binding onto HAG. Thermodynamics parameters analysis and driving force competition experiments showed that hydrogen bonding and hydrophobic forces were the major sources for keeping the complex of HAG-dacomitinib stable. The experimental outcomes also showed that the binding of dacomitinib can lead to the loosening of the skeleton structure of HAG, which led to a slight change in the secondary structure, and also reduces the hydrophobicity of the microenvironment of Trp and Tyr residues. The binding sites of dacomitinib on HAG and the contribution of key amino acid residues to the binding reaction were determined by molecular docking and molecular dynamics (MD) simulation. In addition, it was found that there was a synergistic effect between dacomitinib and Mg2+ and Co2+ ions. Mg2+ and Co2+ could increase the Kb of dacomitinib to HAG and prolong the half-life of dacomitinib.

Design and characterization of BSA-mycophenolic acid nanocomplexes: Antiviral activity exploration

The interactions between bovine serum albumin (BSA) and mycophenolic acid (MPA) were investigated in silico through molecular docking and in vitro, using fluorescence spectroscopy. Dynamic light scattering and scanning electron microscopy were used to figure out the structure of MPA-Complex (MPA-C). The binding affinity between MPA and BSA was determined, yielding a Kd value of (12.0 ± 0.7) μM, and establishing a distance of 17 Å between the BSA and MPA molecules. The presence of MPA prompted protein aggregation, leading to the formation of MPA-C. The cytotoxicity of MPA-C and its ability to fight Junín virus (JUNV) were tested in A549 and Vero cell lines. It was found that treating infected cells with MPA-C decreased the JUNV yield and was more effective than free MPA in both cell line models for prolonged time treatments. Our results represent the first report of the antiviral activity of this type of BSA-MPA complex against JUNV, as assessed in cell culture model systems. MPA-C shows promise as a candidate for drug formulation against human pathogenic arenaviruses.

Polydopamine-Coated Polymer Nanofibers for In Situ Protein Loading and Controlled Release

Nanofibrous polymeric materials, combined with protein therapeutics, play a significant role in biomedical and pharmaceutical applications. However, the upload of proteins into nanofibers with a high yield and controlled release has been a challenging issue. Here, we report the in situ loading of a model protein (bovine serum albumin) into hydrophilic poly(vinyl alcohol) nanofibers via ice-templating, with a 100% protein drug loading efficiency. These protein-loaded nanofibers were further coated by polydopamine in order to improve the nanofiber stability and achieve a controlled protein release. The mass ratio between poly(vinyl alcohol) and bovine serum albumin influenced the percentage of proteins in composite nanofibers and fiber morphology. More particles and less nanofibers were formed with an increasing percentage of bovine serum albumin. By varying the coating conditions, it was possible to produce a uniform polydopamine coating with tunable thickness, which acted as an additional barrier to reduce burst release and achieve a more sustained release profile.

Unraveling the underlying mechanism of interactions between astaxanthin geometrical isomers and bovine serum albumin

The health benefits of astaxanthin (AST) are related to its geometric isomers. Generally, functional activity is realized by the interactions between active substances and transporters. Hereto, bovine serum albumin (BSA), as a model-binding protein and transporter, is able to recognize and transport isomers of active substances through binding with them. However, differences in the binding mechanism of isomers to BSA may affect the functional activities of isomers through the "binding-transport-activity" chain reaction. Thus, this study sought to elucidate the interactions between AST geometrical isomers and BSA using multi-spectroscopy, surface plasmon resonance and molecular docking. The results showed that Z-AST displayed more interacting amino acid residues and lower thermodynamic parameters than all-E-AST. Meanwhile, the order of binding affinity to BSA was 13Z-AST (1.56 × 10-7 M) > 9Z-AST (2.70 × 10-7 M) > all-E-AST (4.01 × 10-7 M), indicating that Z-AST possessed stronger binding ability to BSA. Moreover, AST isomers were located at the junction between subdomains ⅡA and ⅢA of BSA, and showed the same interaction forces (hydrogen bond and van der Waals force) as well as kinetic processes (slow combination, slow dissociation). These interaction parameters provide valuable insights into their pharmacokinetics in vivo, and it was of great significance to explain the potential differences among AST isomers in functional activities.

Interaction mechanism of a pesticide, Azoxystrobin with bovine serum albumin: Assessments through fluorescence, UV-Vis absorption, electrochemical and molecular docking simulation techniques

The current study's objective was to investigate how an antifungal pesticide Azoxystrobin (AZO) interacts with bovine serum albumin (BSA) under conditions that simulate a physiological medium (pH 7.4). This investigation was carried out using various experimental (UV-Vis absorption, steady-state fluorescence and 3-D fluorescence spectroscopies, and electrochemical) and theoretical (molecular docking and molecular dynamics simulations) methods. The fluorescence quenching data demonstrated that AZO caused fluorescence quenching in BSA, and this quenching process was attributed to the static quenching mechanism. By examining the fluorescence quenching of BSA at three different temperatures, it was determined that the binding constants for the AZO-BSA complexes were approximately 104 M-1 in magnitude, while the same magnitude of the binding constant was found by the electrochemical method. This indicates that the interaction between AZO and BSA was of moderate strength. This was further validated by the changes observed in the UV-Vis spectrum of BSA following the addition of AZO. The thermodynamic information, including ΔH and ΔS, revealed that the interaction forces primarily involved van der Waals forces as well as hydrogen bonds. The negative Gibbs free energy indicated that the reaction is spontaneous. In the theoretical investigation, the comparison highlights a remarkable consistency in how AZO interacts with the BSA active site over various time points. Hydrogen bonding and hydrophobic interactions consistently play a role in ensuring the stable and specific binding of the ligand. Moreover, the 3-D fluorescence spectral findings revealed alterations in the surrounding microenvironment of protein fluorophores when AZO binds. Upon analyzing the electrochemical data, it was observed that there was a consistent decrease in the peak currents of AZO when BSA was added to solutions containing AZO. The primary cause of this decrease in the peak currents was the reduction in the equilibrium concentration of AZO due to the addition of BSA. Furthermore, the formation of a non-electroactive complex between BSA and AZO, which impedes electron transport between AZO and the working electrode, accounts for these decreases. As a result, it can be said that the understanding of how AZO binds to BSA offers valuable insights that can be applied in the food, human health, and environment sectors.

Molecular interactions and binding dynamics of Alpelisib with serum albumins: insights from multi-spectroscopic techniques and molecular docking

Alpelisib (ALP) is a potent anti-cancer drug showing promising activity against advanced breast cancers. Hence, profound understanding of its binding dynamics within the physiological system is vital. Herein, we have investigated interaction of ALP with human serum albumin (HSA) and bovine serum albumin (BSA) using spectroscopic techniques like absorption, fluorescence, time-resolved, synchronous and 3D-fluorescence, FRET, FT-IR, CD, and molecular docking studies. The intrinsic fluorescence of both BSA and HSA quenched significantly by ALP with an appreciable red shift in its emission maxima. Stern-Volmer analysis showed increase in Ksv with temperature indicating involvement of dynamic quenching process. This was further validated by no significant change in absorption spectrum of BSA and HSA (at 280 nm) upon ALP interaction, and by results of fluorescence time-resolved lifetime studies. ALP exhibited moderately strong binding affinity with BSA (of the order 106 M-1) and HSA (of the order 105 M-1), and the major forces accountable for stabilizing the interactions are hydrophobic forces. Competitive drug binding experiments and molecular docking suggested that ALP binds to site I in subdomain IIA of BSA and HSA. The Förster distance r was found to be less than 8 nm and 0.5 Ro < r < 1.5 Ro which suggests possible energy transfer between donors BSA/HSA and acceptor ALP. Synchronous and 3D-fluoresecnce, FT-IR and CD studies indicated that ALP induces conformational changes of BSA and HSA upon interaction.Communicated by Ramaswamy H. Sarma.

New ionic liquids based on 5-fluorouracil: Tuning of BSA binding and cytotoxicity

In this work, we describe the synthesis, interactions with bovine serum albumin, and cytotoxicity of new ionic liquids based on 5-fluorouracil (API-ILs) with different cations (imidazolium, choline, isoquinolinium, guanidinium). The secondary and tertiary structure of BSA in solutions with different concentrations of API-ILs was monitored by the circular dichroism (CD) technique. The addition of API-ILs does not lead to structural changes in BSA. A quenching of fluorescence spectra intensity of BSA in presence of all API-ILs was observed, allowing the quantification of binding between API-ILs and BSA. The preferred localization of both ions in API-ILs differs significantly depending on the structure of the cation according to molecular docking. The aggregation of BSA in presence of API-ILs was analyzed by the dynamic light scattering (DLS) method, revealing a moderate increase in particle size. Cytotoxicity and selectivity of API-ILs on cancer and normal cell lines were estimated, showing a clear modification of the pharmaceutic activity of ionic liquid compared to 5-fluorouracil.

Binding studies of potential amyloid-β inhibiting chalcone derivative with bovine serum albumin

Chalcones (α-phenyl-β-benzoylethylene) and their natural-source derivatives have been investigated for their remarkable biological activities, like neuroprotective, anti-inflammatory, and anti-tumor properties. A triazole chalcone ligand (E)-3-(4-(dimethylamino)phenyl)-1-(4-((1-(2-(4-((E)-3-(4(dimethylamino)phenyl)acryloyl)phenoxy)ethyl)-1H-1,2,3-triazol-4-yl)methoxy)phenyl)prop-2-en-1-one (L1) was synthesized by Cu(I)- catalysed click reaction. The mechanistic properties of L1 for therapy were evaluated by analyzing the binding interactions between L1 and bovine serum albumin (BSA) through photophysical and computational studies. The structural elucidation of ligand L1 was carried out by NMR and mass spectrometry. The Aβ inhibitory activity of L1 was studied by thioflavin T assay and transmission electron microscopy. The biomolecular interaction of L1 with bovine serum albumin was examined through multi-spectroscopic techniques in combination with in silico studies. UV-Visible absorption, fluorescence spectroscopy, circular dichroism, Förster resonance energy transfer, and three-dimensional fluorescence studies confirmed the formation of a BSA-L1 complex. The potential binding sites, mechanism of interactions, and variations in the environment of tyrosine and tryptophan amino acid residues of BSA were assessed at different temperatures. The binding constant for the Static quenching mechanism of intrinsic fluorescence of BSA was of the order of 105 M-1. The esterase enzyme activity assay in the presence of L1 revealed an increase in the protein enzyme activity. Molecular docking studies suggested L1 was predominantly bound to BSA by hydrogen bonds and Van der Waals forces.

Induced Circular Dichroism Analysis of Thermally Induced Conformational Changes on Protein Binding Sites Under a Crowding Environment

Protein-ligand interactions in crowded cellular environments play a crucial role in biological functions. The crowded environment can perturb the overall protein structure and local conformation, thereby influencing the binding pathway of protein-ligand reactions within the cellular milieu. Therefore, a detailed understanding of the local conformation is crucial for elucidating the intricacies of protein-ligand interactions in crowded cellular environments. In this study, we investigated the feasibility of induced circular dichroism (ICD) using 8-anilinonaphthalene-1-sulfonic acid (ANS) for local conformational analysis at the binding site in a crowding environment. Bovine serum albumin (BSA) concentration-dependent measurements were performed to assess the feasibility of ANS-ICD for analyzing protein interior binding sites. The results showed distinct changes in the ANS-ICD spectra of BSA solutions, indicating their potential for analyzing the internal conformation of proteins. Moreover, temperature-dependent measurements were performed in dilute and crowding environments, revealing distinct denaturation pathways of BSA binding sites. Principal component analysis of ANS-ICD spectral changes revealed lower temperature pre-denaturation in the crowded solution than that in the diluted solution, suggesting destabilization of binding sites owing to self-crowding repulsive interactions. The established ANS-ICD method can provide valuable conformational insights into protein-ligand interactions in crowded cellular environments.

Bovine Serum Albumin as a Platform for Designing Biologically Active Nanocarriers-Experimental and Computational Studies

Due to the specificity of their structure, protein systems are adapted to carry various ligands. The structure of many proteins potentially allows for two types of immobilization of a therapeutic agent, either on the outer surface of the protein or within the protein structure. The existence of two active sites in BSA's structure, the so-called Sudlow I and II, was confirmed. The conducted research involved determining the effectiveness of BSA as a potential carrier of 5-fluorouracil (5FU). 5-fluorouracil is a broad-spectrum anticancer drug targeting solid tumors. The research was carried out to estimate the physicochemical properties of the system using complementary measurement techniques. The optimization of the complex formation conditions made it possible to obtain significant correlations between the form of the drug and the effective localization of the active substance in the structure of the protein molecule. The presence of two amino groups in the 5FU structure contributes to the deprotonation of the molecule at high pH values (pH > 8) and the transition to the anionic form (AN1 and AN3). To investigate the binding affinity of the tautomeric form with BSA, UV-vis absorption, fluorescence quenching, zeta potential, QCM-D, and CD spectroscopic studies were performed. The experimental research was supported by molecular dynamics (MD) simulations and molecular docking. The simulations confirm the potential location of 5FU tautomers inside the BSA structure and on its surface.

Spectroscopic and molecular docking study of three kinds of cinnamic acid interaction with pepsin

In this work, under simulated physiological conditions (pH = 2.2, glycine hydrochloric acid buffer solution), the interactions of cinnamic acid (CA), m-hydroxycinnamic acid (m-CA) and p-hydroxycinnamic acid (p-CA) with pepsin were studied by fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, circular dichroism (CD) spectroscopy, Fourier transform infrared spectroscopy (FTIR), molecular docking and molecular dynamic simulation (MD). The spectrogram results showed that these three kinds of CA had a strong ability to quench the intrinsic fluorescence of pepsin, and the quenching effects were obvious with the increase of concentration of these three kinds of molecules. The quenching mechanism of CA, m-CA and p-CA on the fluorescence of pepsin was static quenching. In addition, a stable complex was formed between three kinds of CA with pepsin. Thermodynamic data and docking information suggested that three kinds of CA combine with pepsin were mainly driven by electrostatic force and hydrogen bond. The binding constant and the number of binding sites were determined. The interaction of CA, m-CA and p-CA with pepsin was spontaneous, and accompanied by non-radiative energy transfer. The results from CD, FTIR, UV-Vis and synchronous fluorescence spectra measurements manifested that the secondary structure of pepsin was changed by the binding of three kinds of CA. The β-sheet of pepsin increased after the interaction with three kinds of CA. The assay results of pepsin activity showed that three kinds of CA led to a decrease in pepsin activity within the investigated concentrations. Molecular docking investigation revealed the formation of polar hydrogen bonds as well as hydrophobic interactions between three kinds of CA with pepsin, and the ligand within the binding pocket of pepsin. MD results implied the formation of a stable complex between three kinds of CA and pepsin. The research suggested that cinnamic acid and its derivatives could be a potential effect on the structure and properties of digestive enzyme.

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.

A multi-spectroscopic and molecular docking approach for DNA/protein binding study and cell viability assay of first-time reported pendent azide bearing Cu(II)-quercetin and dicyanamide bearing Zn(II)-quercetin complexes

In the current study, one new quercetin-based Zn(II) complex [Zn(Qr)(CNNCN)(H2O)2] (Complex 1) which is developed by condensation of quercetin with ZnCl2 in the presence of NaN(CN)2 and Cu(II) complex [Cu(Qr)N3(CH3OH)(H2O)] (complex 2) which is developed by the condensation reaction of quercetin and CuCl2 in presence of NaN3, are thoroughly examined in relation to their use in biomedicine. The results of several spectroscopic studied confirm the structure of both the complexes and the Density Functional Theory (DFT) study helps to optimize the structure of complex 1 and 2. After completion of the identification process, DNA and Human Serum Albumin (HSA) binding efficacy of both the investigated complexes are performed by implementing a long range of biophysical studies and a thorough analysis of the results unveils that complex 1 has better interaction efficacy with the macromolecules than complex 2. The binding efficacy of complex 1 is comparatively higher towards both macromolecules because of its pure groove binding mode during interaction with DNA and the presence of an extra H-bond during connection with HSA. The experimental host-guest binding results is fully validated by molecular docking study. Interestingly complex 1 shows better antioxidant properties than complex 2, as well as quercetin, and it has strong anticancer property with minimal damage to normal cells, which is proved by the MTT assay study. Better DNA and HSA binding efficacy of 1 may be the reason for the better anticancer property of complex 1.

Journey of micronanoplastics with blood components

The entry of micro- and nanoplastics (MNPs) into the human body is inevitable. They enter blood circulation through ingestion, inhalation, and dermal contact by crossing the gut-lung-skin barrier (the epithelium of the digestive tract, the respiratory tract, and the cutaneous layer). There are many reports on their toxicities to organs and tissues. This paper presents the first thorough assessment of MNP-driven bloodstream toxicity and the mechanism of toxicity from the viewpoint of both MNP and environmental co-pollutant complexes. Toxic impacts include plasma protein denaturation, hemolysis, reduced immunity, thrombosis, blood coagulation, and vascular endothelial damage, among others, which can lead to life-threatening diseases. Protein corona formation, oxidative stress, cytokine alterations, inflammation, and cyto- and genotoxicity are the key mechanisms involved in toxicity. MNPs change the secondary structure of plasma proteins, thereby preventing their transport functions (for nutrients, drugs, oxygen, etc.). MNPs inhibit erythropoiesis by influencing hematopoietic stem cell proliferation and differentiation. They cause red blood cell and platelet aggregation, as well as increased adherence to endothelial cells, which can lead to thrombosis and cardiovascular disease. White blood cells and immune cells phagocytose MNPs, provoking inflammation. However, research gaps still exist, including gaps regarding the combined toxicity of MNPs and co-pollutants, toxicological studies in human models, advanced methodologies for toxicity analysis, bioaccumulation studies, inflammation and immunological responses, dose-response relationships of MNPs, and the effect of different physiochemical characteristics of MNPs. Furthermore, most studies have analyzed toxicity using prepared MNPs; hence, studies must be undertaken using true-to-life MNPs to determine the real-world scenario. Additionally, nanoplastics may further degrade into monomers, whose toxic effects have not yet been explored. The research gaps highlighted in this review will inspire future studies on the toxicity of MNPs in the vascular/circulatory systems utilizing in vivo models to enable more reliable health risk assessment.

Developing targeted drug delivery carriers for breast cancer using glutathione-sensitive doxorubicin-coupled glycated bovine serum albumin nanoparticles

Incorporation of the nano-based carriers into drug delivery provides a promising alternative to overcome the limitations of the conventional chemotherapy. Doxorubicin (DOXO) is an effective chemotherapeutic drug widely used in chemotherapy for breast cancer treatment. A globular protein bovine serum albumin (BSA) holds great potential as carriers in pharmaceutical applications. This work is aimed at developing the DOXO-coupled glycated BSA nanoparticles via desolvation method for improving the capability of targeting the GLUT5 transporters over-expressed on breast cancer cells. Fructosamine assay and Fourier transform infrared spectroscopy were employed to determine the content of fructosamine structure and structural changes on the surfaces of nanoparticles, respectively. Additionally, the synthesized BSA nanoparticles were further characterized by electron microscopy and dynamic light scattering. Results revealed that the DOXO-coupled glycated BSA nanoparticles were spherically shaped with a hydrodynamic diameter of ~60.74 nm and a ζ-potential of ~ - 42.20 mV. Moreover, the DOXO release behavior of as-synthesized DOXO-coupled glycated BSA nanoparticles was examined under different conditions. Finally, the DOXO-coupled glycated BSA nanoparticles were found to exhibit cytotoxicity toward both MCF-7 and MDA-MB-231 cells. Our findings evidently suggested that the drug-coupled glycated BSA nanoparticles serve as the potential candidates for targeted drug delivery platform used in breast cancer therapy.

Investigation on the interaction of aromatic organophosphate flame retardants with human serum albumin via computer simulations, multispectroscopic techniques and cytotoxicity assay

Organophosphate flame retardants (OPFRs) are newly emerging estrogenic environmental pollutants, which attracted widespread public interest owing to their potential threats to human. Here, the interaction between two typical aromatic OPFRs, TPHP/EHDPP and HSA was researched by different experiments. Experimental results indicated that TPHP/EHDPP can insert the site I of HSA and be encircled by several amino acid residues, Asp451, Glu292, Lys195, Trp214 and Arg218 played vital roles in this binding process. At 298 K, the Ka value of TPHP-HSA complex was 5.098 × 104 M-1, and the Ka value of EHDPP-HSA was 1.912 × 104 M-1. Except H-bonds and van der Waals forces, the π-electrons on the phenyl ring of aromatic-based OPFRs played a pivotal role in maintaining the stability of the complexes. The content alterations of HSA were observed in the present of TPHP/EHDPP. The IC50 values of TPHP and EHDPP were 157.9 μM and 31.14 μM to GC-2spd cells, respectively. And the existence of HSA has a regulatory effect on the reproductive toxicity of TPHP/EHDPP. In addition, the results of present work implied Ka values of OPFRs and HSA are possible to be a useful parameter for evaluating their relative toxicity.

Impacts of Halogen Substitutions on Bisphenol A Compounds Interaction with Human Serum Albumin: Exploring from Spectroscopic Techniques and Computer Simulations

Bisphenol A (BPA) is an endocrine-disrupting compound, and the binding mechanism of BPA with carrier proteins has drawn widespread attention. Halogen substitutions can significantly impact the properties of BPA, resulting in various effects for human health. Here, we selected tetrabromobisphenol A (TBBPA) and tetrachlorobisphenol A (TCBPA) to investigate the interaction between different halogen-substituted BPAs and human serum albumin (HSA). TBBPA/TCBPA spontaneously occupied site I and formed stable binary complexes with HSA. Compared to TCBPA, TBBPA has higher binding affinity to HSA. The effect of different halogen substituents on the negatively charged surface area of BPA was an important reason for the higher binding affinity of TBBPA to HSA compared to TCBPA. Hydrogen bonds and van der Waals forces were crucial in the TCBPA-HSA complex, while the main driving factor for the formation of the TBBPA-HSA complex was hydrophobic interactions. Moreover, the presence of TBBPA/TCBPA changed the secondary structure of HSA. Amino acid residues such as Lys199, Lys195, Phe211, Arg218, His242, Leu481, and Trp214 were found to play crucial roles in the binding process between BPA compounds and HSA. Furthermore, the presence of halogen substituents facilitated the binding of BPA compounds with HSA.

Molecular Recognition Study toward the Mitochondrial Electron Transport Chain Inhibitor Mubritinib and Human Serum Albumin

The ability to bind plasma proteins helps in comprehending relevant aspects related to the pharmacological properties of many drugs. Despite the vital role of the drug mubritinib (MUB) in the prophylaxis of various diseases, its interaction with carrier proteins still needs to be clarified. The present work focuses on the interaction between MUB and Human serum albumin (HSA), investigated by employing multispectroscopic, biochemical, and molecular docking approaches. The results reveal that MUB has quenched HSA intrinsic fluorescence (following a static mechanism) by attaching very close (r = 6.76 Å) and with moderate affinity (Kb ≈ 104 M-1) to the protein site I (mainly by H-bonds, hydrophobic and Van der Waals forces). On one side, the HSA-MUB interaction has been accompanied by a slight disturbance in the HSA chemical environment (around the Trp residue) and protein secondary structure modifications. On another side, MUB competitively inhibits HSA esterase-like activity, which is very similar to other Tyrosine kinase inhibitors, and evidence that protein functional alterations have been triggered by MUB interaction. In summary, all of the presented observations can shed light on diverse pharmacological factors associated with drug administration.

Fructosylation of human insulin causes AGEs formation, structural perturbations and morphological changes: an in silico and multispectroscopic study

Fructosylation of proteins results in the formation of advanced glycation end-products (AGEs). A diet rich in fructose along with hyperglycemia can cause fructose mediated glycation (fructosylation) of proteins, which results in AGEs formation. Insulin is a peptide hormone that is glycated when exposed to carbohydrates such as glucose. In this study, we have analysed the interaction of insulin with fructose and biophysically characterized fructose modified insulin. In silico studies performed through molecular docking and molecular dynamics simulation revealed that fructose binds to insulin with strong affinity resulting in the formation of insulin-fructose complex. Fructosylation of insulin caused hyperchromicity, loss of intrinsic fluorescence, gain in AGEs specific fluorescence and elevated the carbonyl and fructosamine content. Enhanced thioflavin T fluorescence suggested the presence of fibrillar structures at higher concentrations of fructose. Electron microscopy revealed the formation of characteristic amorphous and amyloid like aggregates at lower and higher concentrations of fructose, respectively. These findings show that fructosylation of insulin causes AGEs production, aggregation and alters its gross structural integrity. These changes may reduce the biological activity of insulin that can aggravate conditions like type II diabetes mellitus.Communicated by Ramaswamy H. Sarma.

Cyclodextrins and Their Polymers Affect Human Serum Albumin's Interaction with Drugs Used in the Treatment of Pulmonary Infections

Respiratory infectious diseases have challenged medical communities and researchers. Ceftriaxone, meropenem and levofloxacin are widely used for bacterial infection treatment, although they possess severe side effects. To overcome this, we propose cyclodextrin (CD) and CD-based polymers as a drug delivery system for the drugs under consideration. CD polymers demonstrate higher binding affinity for levofloxacin (Ka ≈ 10⁵ M) compared to drug-CD complexes. CDs slightly alter the drugs' affinity for human serum albumin (HSA), whereas CD polymers increase the drugs' binding affinity up to 100 times. The most significant effect was observed for more the hydrophilic drugs ceftriaxone and meropenem. The drug's encapsulation in CD carriers leads to a decrease in the degree of change in the protein's secondary structure. The drug-CD carrier-HSA complexes demonstrate satisfying antibacterial activity in vitro, and even a high binding affinity does not decrease the drug's microbiological properties after 24 h. The proposed carriers are promising for a drug form with a prolonged drug release.

Deciphering the binding site and mechanism of new methylene blue with serum albumins: A multispectroscopic and computational investigation

Herein, the interaction mechanism of new methylene blue (NMB) with human serum albumin (HSA) and bovine serum albumin (BSA) was carefully investigated both experimentally and conceptually, employing experimental and insilico analysis. The steady-state emission spectral studies showed that the emission intensity of HSA and BSA was quenched significantly by NMB. The findings of the Stern-Volmer and double logarithmic plot revealed that the observed emission quenching process was through a static quenching mechanism and the measured binding constant values (K_b) for HSA-NMB and BSA-NMB are 2.766 and 1.187 × 10⁵ dm³ mol^-1 respectively. The time-resolved fluorescence lifetime measurement and UV-vis absorption investigation further verify the complex formation between NMB and HSA/BSA. The assessment of thermodynamic parameters disclosed the binding process was spontaneous driven by hydrogen bonds (H-bond) and van der Waals interactions, which contributed a significant role in the complexation. Moreover, the secondary structural conformation and microenvironment of HSA/BSA were modified in the presence of NMB, as evidenced by circular dichroism and synchronous fluorescence data. Molecular docking study predicted a plausible binding mode of NMB inside the binding pocket of HSA and BSA. These results demonstrated that the stabilized NMB is found at the Subdomain IIA (site I) of both the proteins and the results were correlated well with the competitive binding assay. Additionally, the principal components analysis revealed less variation of docked poses for HSA, while, more dispersed docked poses were observed for the BSA model. This also highlights the effects of docking towards a modeled protein (BSA). Molecular dynamic (MD) simulation based binding free energy (ΔG_mmgbsa) estimation obtained at 298, 303, 308 and 313 K, were in good agreement with our experimental (ΔG_bind) values.

Perception of the interaction behavior between pepsin and the antimicrobial drug secnidazole with combined experimental spectroscopy and computer-aided techniques

Drug-pepsin interaction possibly affects pepsin activity, leads to undesirable shift of its functionality, and likely induces adverse effects in the gastrointestinal tract. The present study aims at exploring the interaction of pepsin with the antiprotozoal/antibacterial drug secnidazole adopting a combination of experimental spectroscopy and computational techniques. For this purpose, different spectroscopic methods including fluorescence, synchronous fluorescence, UV-Visible absorption, and infrared spectroscopy were adopted and coordinated with in silico analysis via molecular docking. The employed synchronized approaches evidenced that; pepsin interacted with secnidazole via static mechanism at stomach pH inferring some consequent conformational changes in the structure of pepsin. Thermodynamic study of drug-pepsin interaction demonstrated that the interaction is spontaneous via van der Waals and hydrogen bonding interaction and the orientation of ligand within pepsin cavity was illustrated by molecular docking. The synchronous fluorescence study proved that tyrosine amino acid residues were involved in the interaction more than tryptophan amino acid residues. Eventually, the combined experimental and molecular docking approaches suggest that secnidazole interacts with pepsin and alter its structure, that finding correlates to gastrointestinal side effects related to secnidazole oral administration.

Effects of combined binding of chlorogenic acid/caffeic acid and gallic acid to trypsin on their synergistic antioxidant activity, enzyme activity and stability

The combined application of multiple natural polyphenols in functional foods may provide better health benefits. The binding of polyphenols with different structures to proteins will affect their respective functions. Spectroscopy and molecular docking were used to investigate the competitive binding of chlorogenic acid (CGA)/caffeic acid (CA) and gallic acid (GA) to trypsin. The effects of different molecular structures and the order of adding the three phenolic acids on the binding were assessed. The stability of trypsin and its docked complexes with CGA/CA/GA was evaluated by molecular dynamics simulation. The effects of the binding process on the activity and thermal stability of trypsin, as well as on the antioxidant activity and stability of CGA/CA/GA were explored. The competitive binding of CGA/CA and GA to trypsin affected their synergistic antioxidant effects. The results may provide a reference for the combined application of CGA/CA and GA in food and pharmaceutical fields.

Biologically active oxovanadium(IV) Schiff base metal complex: antibacterial, antioxidant, biomolecular interaction and molecular docking studies

The oxovanadium(IV) Schiff base metal complex (ISNPV) have been synthesized as well as characterized by using micro analytical and traditional spectroscopic techniques. The spectral findings were utilized to validate the formation of ISNPV with structure exhibited square pyramidal geometry. The in vitro antibacterial activities of ISNPV were investigated to five different bacterial stains such as S. aureus, S. epidermidis, B. cereus, B. amyloliquefaciens and B. subtilis. The obtained result have suggested that the ISNPV has highest antibacterial activity against S. aureus than the other bacterial stains. The in vitro antioxidant activity like DPPH free radical scavenging assay method was studied by ISNPV in DMSO medium. Because it scavenges all free radicals, the ISNPV possesses higher antioxidant activity than the free ligand. UV-visible absorption and emission spectral techniques were used to investigate the binding of CT-DNA to the ISNPV. Both the spectral data indicate that the ISNPV binds the double helix structure of CT-DNA via an intercalation mode. Additionally, investigate the interactions of ISNPV with the protein molecules like BSA/HAS has been investigated using absorption and emission techniques. The absorption intensity of metal complex increases as well as the emission intensity of protein molecules ability decreases due to the binding nature of ISNPV with BSA/HSA protein molecules. The binding nature of ISNPV with bio molecules such as CT-DNA, BSA and HSA was also validated using molecular docking approach.

System-wide health risk prediction for 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene(MBP), a major active metabolite of environmental pollutant and food contaminant - Bisphenol A

Human exposure to plastic contaminated foods and environmental micro/nano plastic derived chemicals necessitates system-wide health risk assessment. Hence, current study intend to explore the mode of action (MoA) based adverse outcome pathways of 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), the major active metabolite of bisphenol A (BPA). The computational study employed broad range of target prediction, systems biology tools and molecular docking protocols. Further, validation of MBP targets was done using protein-ligand fluorescence quenching assay, endothelial cell culture and chicken embryo vascular angiogenesis models. Interestingly, the current results illustrate that various physiological signaling pathways (MAPK and VEGF related angiogenesis signaling) and disease progression pathways (hypertension, cancer and endocrine disorders) were enriched as potential targets of MBP. Further, docking studies highlights the possible binding mechanism of MBP with important targets including endothelial nitric oxide synthase (eNOS) and serum albumin (BSA). In addition, the validation studies on MBP-BSA interaction (fluorescence quenching), eNOS derived nitric oxide (NOx) generation in endothelial cells and chicken embryo angiogenesis support the system-wide impacts of MBP with highlights on cardiovascular pathogenesis. Thus, the current observation provides novel insights into the system wide impacts of MBP for the futuristic health risk assessment of plastic derived chemicals.