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

Biophysical insight into the interaction mechanism of 4-bromo-N-(thiazol-2-yl)benzenesulfonamide and human serum albumin using multi-spectroscopic and computational studies

4-Bromo-N-(thiazol-2-yl)benzenesulfonamide (1) is enriched with bioactive components and is highlighted for its pharmacological properties. However, its pharmacokinetic characteristics are yet to be reported. The interaction of compound 1 with carrier proteins in the bloodstream is an important factor that affects its potential therapeutic efficacy. This study aimed to elucidate the pharmacokinetic mechanisms of compound 1 in relation to human serum albumin (HSA) using multi-spectroscopic and computational techniques. Its predicted drug-like properties revealed no mutagenicity, although potential hepatotoxicity and interactions with certain cytochrome P450 enzymes were observed. Spectroscopic analyses extensively provided the interaction between HSA and 1 through a static fluorescence quenching mechanism with spontaneous hydrophobic interactions and hydrogen bonding. The binding constant of the HSA‒1 complex was relatively moderate to strong at a level of 106 M-1. Various spectroscopic techniques including ultraviolet-visible, Fourier transform infrared, and circular dichroism spectroscopies indicated that its binding induced alteration in the α-helix content of HSA. Competitive binding and molecular docking studies designated the preferential binding of 1 to sub-structural domain IIA binding site I of HSA. Molecular dynamic simulations further illustrated the formation of a stable complex between 1 and HSA, accompanied by conformational changes in the protein. Importantly, esterase capacity of the HSA‒1 complex increased compared to the free HSA. Therefore, elucidation of the HSA‒1 binding mechanism provides valuable insights into the pharmacokinetics, suggesting potential benefits for the further development of 1 as a therapeutic agent.

A comprehensive investigation of the nano-[Cu2-(DIP)2-EA] effects on HSA through spectroscopic procedures and computer simulations

In this research, the toxicity of nano-[Cu2-(DIP)2-EA], a metal nano-complex consisting of ellagic acid and bathophenanthroline ligands, on human serum albumin (HSA) at a protein level was investigated. Molecular docking simulations and spectral analyses were conducted in a simulated physiological environment at pH 7.4 to explore the interaction of nano-[Cu2-(DIP)2-EA] with HSA. The results represented an increase in albumin absorption upon exposure to nano-[Cu2-(DIP)2-EA], demonstrating significant interaction between the two compounds. Steady-state and time-resolved fluorescence measurements pointed out that nano-[Cu2-(DIP)2-EA] induced static quenching of the albumin's intrinsic fluorescence with a high binding affinity of approximately 106 mol/L in a 1:1 interaction ratio. The thermodynamic variables clarified that binding of nano-[Cu2-(DIP)2-EA] to albumin occurs spontaneously and primarily driven by van der Waals interactions and H-bonds. The results of the computer simulations and the binding displacement experiments utilizing the site markers warfarin and ibuprofen revealed that nano-[Cu2-(DIP)2-EA] binds to site I within the subdomain IIA of albumin. Circular dichroism analysis elaborated that nano-[Cu2-(DIP)2-EA] slightly perturbed the microenvironment around of tryptophan residues and diminished the α-helix structure stability to a negligible amount.

The hemostatic molecular mechanism of Sanguisorbae Radix's pharmacological active components based on HSA: Spectroscopic investigations, molecular docking and dynamics simulation

The interactions between human serum albumin (HSA) and the hemostatic components of the Chinese medicine Sanguisorbae Radix (SR), specifically phenolic acid compounds such as caffeic acid (CA), ferulic acid (FA) and their 1:1 mixture (1:1) were studied to investigate the molecular mechanism underlying the hemostatic effect of SR. Network pharmacology combined with the experimental and computational data revealed that HSA is one of the hemostatic targets to SR phenolic acids. SDS-PAGE and multi-spectroscopy demonstrated that the phenolic acids bind to the Sudlow site I on HSA, altering its structure and influencing its migration velocity. There is an observed synergistic effect upon the mixture of CA and FA. Quantum chemistry, molecular docking, and molecular dynamics simulations indicate that the binding of phenolic acids to HSA is stable, and variations in binding efficiency are associated with the hydrophobicity of the substituent at the C3 position of the side chain, and also, the key amino acids and functional groups for hemostasis of SR were identified, along with the active sites that contribute to the synergistic enhancement by phenolic acids.

The mechanism of interaction between tri-para-cresyl phosphate and human serum protein: A multispectroscopic and in-silico study

Organophosphate flame retardants (OPFRs) pose the significant risks to the environment and human health and have become a serious public health issue. Tricresyl phosphates (TCPs), a group of aryl OPFRs, exhibit neurotoxicity and endocrine disrupting toxicity. However, the binding mechanisms between TCPs and human serum albumin (HSA) remain unknown. In this study, through fluorescence and ultraviolet-visible (UV-vis) absorption spectroscopy, molecular docking and molecular dynamics (MD), tri-para-cresyl phosphate (TpCP) was selected to explore potential interactions between HSA and TCPs. The results of the fluorescence spectroscopy demonstrated that a decrease in the fluorescence intensity of HSA and a blue shift were observed with the increasing concentrations of TpCP. The binding constant (Ka) was 2.575 × 104 L/mol, 4.701 × 104 L/mol, 5.684 × 104 L/mol and 9.482 × 104 L/mol at 293 K, 298 K, 303 K, and 310 K, respectively. The fluorescence process between HSA and TpCP involved a mix of static and dynamic quenching mechanism. The gibbs free energy (ΔG0) of HSA-TpCP system was -24.452 kJ/mol, -25.907 kJ/mol, -27.363 kJ/mol, and - 29.401 kJ/mol at 293 K, 298 K, 303 K, and 310 K, respectively, suggesting that the HSA-TpCP reaction was spontaneous. The enthalpy change (ΔH0) and thermodynamic entropy change (ΔS0) of the HSA-TpCP system were 60.83 kJ/mol and 291.08 J/(mol·>k), respectively, indicating that hydrophobic force was the major driving force in the HSA-TpCP complex. Furthermore, multispectral analysis also revealed that TpCP could alter the microenvironment of tryptophan residue and the secondary structure of HSA and bind with the active site I of HSA. Molecular docking and MD simulations confirmed that TpCP could spontaneously form a stable complex with HSA, which was consistent with the fluorescence experimental results. This study provides novel insights into the mechanisms of underlying the transportation and distribution of OPFRs in humans.

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

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

Transition-Metal Catalyzed Synthesis of Pyrimidines: Recent Advances, Mechanism, Scope and Future Perspectives

Pyrimidine is a pharmacologically important moiety that exhibits diverse biological activities. This review reflects the growing significance of transition metal-catalyzed reactions for the synthesis of pyrimidines (with no discussion being made on the transition metal-catalyzed functionalization of pyrimidines). The effect of different catalysts on the selectivity/yields of pyrimidines and catalyst recyclability (wherever applicable) are described, together with attempts to illustrate the role of the catalyst through mechanisms. Although several methods have been researched for synthesizing this privileged scaffold, there has been a considerable push to expand transition metal-catalyzed, sustainable, efficient and selective synthetic strategies leading to pyrimidines. The aim of the authors with this update (2017-2023) is to drive the designing of new transition metal-mediated protocols for pyrimidine synthesis.

Determining the stoichiometry and binding constant of Lamotrigine with human serum albumin using voltammetry analysis and molecular modeling

In this study, the interaction of an anticonvulsant drug that used in the treatment of epilepsy, Lamotrigine (LTG) with the most important transport protein of the blood, human serum albumin (HSA) has been studied by using the electrochemical methods and molecular modeling techniques. For this purpose, a simple carbon paste electrode (CPE) was applied for electrocatalytic oxidation and investigation of LTG interaction with HSA. The stoichiometry of the complex between LTG and HSA and the binding constant (Kb) of the reaction were calculated from the calibration curves. The results show that binding of LTG to HSA formed two complexes with different stoichiometries with Kb1 (2.46 × 103) and Kb2 (1.75 × 107), respectively. In agreement with the experimental data, molecular modeling approach also confirmed that LTG can bind to the subdomain IIA and IB of HSA.Communicated by Ramaswamy H. Sarma.

Synthesis, Biological, Spectroscopic and Computational Investigations of Novel N-Acylhydrazone Derivatives of Pyrrolo[3,4-d]pyridazinone as Dual COX/LOX Inhibitors

Secure and efficient treatment of diverse pain and inflammatory disorders is continually challenging. Although NSAIDs and other painkillers are well-known and commonly available, they are sometimes insufficient and can cause dangerous adverse effects. As yet reported, derivatives of pyrrolo[3,4-d]pyridazinone are potent COX-2 inhibitors with a COX-2/COX-1 selectivity index better than meloxicam. Considering that N-acylhydrazone (NAH) moiety is a privileged structure occurring in many promising drug candidates, we decided to introduce this pharmacophore into new series of pyrrolo[3,4-d]pyridazinone derivatives. The current paper presents the synthesis and in vitro, spectroscopic, and in silico studies evaluating the biological and physicochemical properties of NAH derivatives of pyrrolo[3,4-d]pyridazinone. Novel compounds 5a-c-7a-c were received with high purity and good yields and did not show cytotoxicity in the MTT assay. Their COX-1, COX-2, and 15-LOX inhibitory activities were estimated using enzymatic tests and molecular docking studies. The title N-acylhydrazones appeared to be promising dual COX/LOX inhibitors. Moreover, spectroscopic and computational methods revealed that new compounds form stable complexes with the most abundant plasma proteins-AAG and HSA, but do not destabilize their secondary structure. Additionally, predicted pharmacokinetic and drug-likeness properties of investigated molecules suggest their potentially good membrane permeability and satisfactory bioavailability.

PI3K/mTOR Dual Inhibitor Pictilisib Stably Binds to Site I of Human Serum Albumin as Observed by Computer Simulation, Multispectroscopic, and Microscopic Studies

Pictilisib (GDC-0941) is a well-known dual inhibitor of class I PI3K and mTOR and is presently undergoing phase 2 clinical trials for cancer treatment. The present work investigated the dynamic behaviors and interaction mechanism between GDC-0941 and human serum albumin (HSA). Molecular docking and MD trajectory analyses revealed that GDC-0941 bound to HSA and that the binding site was positioned in subdomain IIA at Sudlow’s site I of HSA. The fluorescence intensity of HSA was strongly quenched by GDC-0941, and results showed that the HSA–GDC-0941 interaction was a static process caused by ground-state complex formation. The association constant of the HSA–GDC-0941 complex was approximately 10⁵ M⁻¹, reflecting moderate affinity. Thermodynamic analysis conclusions were identical with MD simulation results, which revealed that van der Waals interactions were the vital forces involved in the binding process. CD, synchronous, and 3D fluorescence spectroscopic results revealed that GDC-0941 induced the structural change in HSA. Moreover, the conformational change of HSA affected its molecular sizes, as evidenced by AFM. This work provides a useful research strategy for exploring the interaction of GDC-0941 with HSA, thus helping in the understanding of the transport and delivery of dual inhibitors in the blood circulation system.

Molecular Insight into the Binding of Astilbin with Human Serum Albumin and Its Effect on Antioxidant Characteristics of Astilbin

Astilbin is a dihydroflavonol glycoside identified in many natural plants and functional food with promising biological activities which is used as an antioxidant in the pharmaceutical and food fields. This work investigated the interaction between astilbin and human serum albumin (HSA) and their effects on the antioxidant activity of astilbin by multi-spectroscopic and molecular modeling studies. The experimental results show that astilbin quenches the fluorescence emission of HSA through a static quenching mechanism. Astilbin and HSA prefer to bind at the Site Ⅰ position, which is mainly maintained by electrostatic force, hydrophobic and hydrogen bonding interactions. Multi-spectroscopic and MD results indicate that the secondary structure of HSA could be changed because of the interaction of astilbin with HSA. DPPH radical scavenging assay shows that the presence of HSA reduces the antioxidant capacity of astilbin. The explication of astilbin–HSA binding mechanism will provide insights into clinical use and resource development of astilbin in food and pharmaceutical industries.