Evaluation of the interactions between human serum albumin (HSA) and warfarin or diflunisal by using molecular fluorescence using two approaches (original) (raw)
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Journal of pharmaceutical and biomedical analysis, 2018
Interaction thermodynamics between warfarin, a very popular anticoagulant, and Sudlow I binding site of human (HSA) or bovine (BSA) serum albumin have been examined in strictly controlled experimental conditions (HEPES buffer 50 mM, pH 7.4 and 25 °C) by means of isothermal titration calorimetry (ITC), fluorescence spectrometry (FS) and frontal analysis capillary electrophoresis (FA/CE). Each technique is based on measurements of a different property of the biochemical system, and then the results allow a critical discussion about the suitability of each approach to estimate the drug-protein binding parameters. The strongest interaction step is properly evaluated by the three assayed approaches being the derived binding constants strongly consistent: from 4 × 104 to 7 × 104 for HSA and from 0.8 × 105 to 1.2 × 105 for BSA. Binding enthalpy variations also show consistent results: -5.4 and -5.6 Kcal/mol for HSA and -4.3 and -3.7 Kcal/mol for BSA, as measured by ITC and FS, respectively...
Current pharmaceutical design, 2015
Human serum albumin (HSA) is one of the major carrier proteins in the body and constitutes approximately half of the protein found in blood plasma. It plays an important role in lipid metabolism, and its ability to reversibly bind a large variety of pharmaceutical compounds makes it a crucial determinant of drug pharmacokinetics and pharmacodynamics. This review deals with one of the protein's major binding sites "Sudlow I" which includes a binding pocket for the drug warfarin (WAR). The binding nature of this important site can be characterized by measuring the spectroscopic changes when a ligand is bound. Using several drugs, including WAR, and other drug-like molecules as ligands, the results emphasize the nature of Sudlow I as a flexible binding site, capable of binding a variety of ligands by adapting its binding pockets. The high affinity of the WAR pocket for binding versatile molecular structures stems from the flexibility of the amino acids forming the pocket....
Chirality, 2002
Kinetic and equilibrium binding studies were performed on the interaction of warfarin enantiomers with human serum albumin (HSA) in the absence and presence of lorazepam acetate (LoAc) enantiomers. Binding kinetics were followed by recording changes in the fluorescence of warfarin upon binding to HSA using the stopped-flow technique. The binding of (R)-warfarin displayed an exponentially increasing fluorescence, satisfying the two-step mechanism reported previously for the racemate, i.e., a diffusion controlled pre-equilibrium is followed by a slower rearrangement of the complex. In the case of (S)-warfarin, the signal was biphasic: a fast fluorescence enhancement was followed by a slow decline. The different kinetic features indicate that the equilibrium conformations of the [(S)warfarin-HSA] and [(R)-warfarin-HSA] complexes are achieved via different mechanisms. The phenomenon was seen in buffers of different pH and compositions. Equilibrium binding measurements indicated significantly lower molar intrinsic fluorescence for the (S)-warfarin complex, suggesting differences in the microenvironments of the bound enantiomers. In the presence of (S)-LoAc, the allosterically enhanced binding of (S)-warfarin manifested itself in accelerated relaxation kinetics. In accordance with the low molar intrinsic fluorescence determined for the stable ternary complex, the amplitude of the decline in fluorescence became larger.
European journal of advanced chemistry research, 2023
Human serum albumin (HSA) is one of the most important transporters for drugs in the systemic circulation. In this study, we investigated the interaction of rosuvastatin (ROS) and atorvastatin (ATO) with HSA. Binding of a drug molecule to HSA significantly affects the pharmacokinetics of the drug as it increases drug solubility in plasma, decreases toxicity and protects molecules from oxidation. This study was made using fluorescence spectroscopy and molecular modeling approach. Fluorescence spectra were recorded for two different statins brands at seven different concentrations. The results revealed that both statins (ROS and ATO) cause the fluorescence quenching of the HSA solution. ROS and ATO binds strongly to HSA with the binding constant (Kb) of 1.0246×10 6 and 0,9018×10 6 , respectively. In addition, it was observed that high concentrations of ATO cause a shift of the emission maximum towards longer wavelengths (red-shift), which may be due to the unfolding of protein chains or denaturation. Furthermore, it was calculated that HSA possesses one binding site for ROS and ATO. Results from molecular docking showed that ROS has a higher affinity for Sudlow site I compared to Sudlow site II and the main binding forces are hydrogen bonds. ATO has nearly equal affinity for both binding sites on HSA, and the main binding forces are hydrophobic interactions.
Binding study of different drugs with serum albumins
International Journal of Clinical Biochemistry and Research, 2021
Objective: Besides bilirubin and fatty acids are more important among the physiological ligands transported by albumin, drugs constitute the major class of exogenous ligands transported by albumin. Considering the total number of ligands bound to albumin, it is inconceivable to think of the same number of ligand binding sites on albumin molecule, so it seems that same binding sites are shared by several compounds. Thus it is possible that some ligands may be displaced from albumin by other ligands. Various drugs are well known displacer of bilirubin from albumin. Materials and Methods: In the present communication the binding of three drugs namely, Indomethacin, chlorpromazine and oxyphenbutazone to serum albumins (BSA and SSA) under different conditions of pH and ionic strength have been studied by fluorescence quenching technique in order to ascertain the role of various non – covalent interactions. Results and Discussion: The results suggest that in case of indomethacin, a decrea...
A Comprehensive Spectroscopic Analysis of the Ibuprofen Binding with Human Serum Albumin, Part I
Pharmaceuticals, 2020
Human serum albumin (HSA) plays a fundamental role in the human body. It takes part in the transport of exogenic and endogenic substances, especially drugs. Ibuprofen (IBU) is one of the most commonly used non-steroidal anti-inflammatory drugs, used for pain relief, fever relief, and for anti-inflammatory purposes. The binding of ligands with HSA is a significant factor which determines the toxicity and the therapeutic dosages of these substances. The aim of this study was to compare the degree of ibuprofen binding with human serum albumin at various temperatures and protein solution pH values. In order to evaluate conformational changes in HSA caused by interaction with ibuprofen, spectrophotometric (first and second derivatives of the UV-VIS spectrum), and spectrofluorometric analyses were performed concerning the mutual interactions of IBU-HSA. The use of fluorescent spectroscopy allowed for recording fluorescent emissive spectra of HSA (5 × 10−6 mol/dm3) without and with the pre...
Evaluation of alternatives to warfarin as probes for Sudlow site I of human serum albumin
Journal of Chromatography A, 2009
Warfarin is often used as a site-specific probe for examining the binding of drugs and other solutes to Sudlow site I of human serum albumin (HSA). However, warfarin has strong binding to HSA and the two chiral forms of warfarin have slightly different binding affinities for this protein. Warfarin also undergoes a slow change in structure when present in common buffers used for binding studies. This report examined the use of four related, achiral compounds (i.e., coumarin, 7-hydroxycoumarin, 7-hydroxy-4-methylcoumarin, and 4-hydroxycoumarin) as possible alternative probes for Sudlow site I in drug binding studies. High-performance affinity chromatography and immobilized HSA columns were used to compare and evaluate the binding properties of these probe candidates. Binding for each of the tested probe candidates to HSA was found to give a good fit to a two-site model. The first group of sites had moderate-to-high affinities for the probe candidates with association equilibrium constants that ranged from 6.4 × 10 3 M −1 (coumarin) to 5.5 × 10 4 M −1 (4-hydroxycoumarin) at pH 7.4 and 37 • C. The second group of weaker, and probably non-specific, binding regions, had association equilibrium constants that ranged from 3.8 × 10 1 M −1 (7-hydroxy-4-methylcoumarin) to 7.3 × 10 2 M −1 (coumarin). Competition experiments based on zonal elution indicated that all of these probe candidates competed with warfarin at their high affinity regions. Warfarin also showed competition with coumarin, 7-hydroxycoumarin and 7-hydroxy-4-methycoumarin for their weak affinity sites but appeared to not bind and/or compete for all of the weak sites of 4-hydroxycoumarin. It was found from this group that 4-hydroxycoumarin was the best alternative to warfarin for examining the interactions of drugs at Sudlow site I on HSA. These results also provided information on how the major structural components of warfarin contribute to the binding of this drug at Sudlow site I. (D.S. Hage). trifugation [14], equilibrium dialysis [15-17], fluorescence [18,19], UV/vis absorption [19], circular dichroism [20-23], capillary electrophoresis [24-27], surface plasmon resonance , and nuclear magnetic resonance (NMR) spectroscopy . Another technique that has been popular for some time in this type of application is high-performance affinity chromatography (HPAC) . HPAC is a specialized form of HPLC that makes use of an immobilized biological ligand (e.g., HSA) as the stationary phase . It has been previously shown that columns containing immobilized HSA are effective models for soluble HSA in drug binding studies, making it possible to rapidly obtain accurate and precise estimates of the association equilibrium constants and number of binding sites for drugs on HSA, while also providing a means for studying drug-drug competition for this protein . These properties make HPAC and HSA columns appealing for the high throughput screening of drug binding to HSA.
Human serum albumin binding assay based on displacement of a non selective fluorescent inhibitor
Bioorganic & Medicinal Chemistry Letters, 2007
In this paper, we describe a fluorescent antibacterial analog, 6, with utility as a competition probe to determine affinities of other antibacterial analogs for human serum albumin (HSA). Analog 6 bound to HSA with an affinity of 400 ± 100 nM and the fluorescence was environmentally sensitive. With 370 nm excitation, environmental sensitivity was indicated by a quenching of the 530 nm emission when the probe bound to HSA. Displacement of dansylsarcosine from HSA by 6 indicated it competed with compounds that bound at site II (ibuprofen binding site) on HSA. Analog 6 also shifted the NMR peaks of an HSA bound oleic acid molecule that itself was affected by compounds that bound at site II. In addition to binding at site II, 6 interacted at site I (warfarin binding site) as indicated by displacement of dansylamide and the shifting of NMR peaks of an HSA bound oleic acid molecule affected by warfarin site binding. Additional evidence for multiple site interaction was discovered when a percentage of 6 could be displaced by either ibuprofen or phenylbutazone. A competition assay was established using 6 to determine relative affinities of other antibacterial inhibitors for HSA.