Binding Affinity Of Human Serum Albumin Research Articles

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.

Effects of ultraviolet radiation and reactive oxygen species on the structure and ligand-binding ability of human serum albumin for norfloxacin

To explore the influence of ultraviolet radiation (UV) and reactive oxygen species (ROS) on the structure and ligand-binding ability of human serum albumin (HSA) for norfloxacin (NFLX), HSA was treated with UV (HSAUV) and UV/H2O2 (HSAUV/H2O2), respectively. The structure difference of HSA, HSAUV and HSAUV/H2O2 were investigated by Fourier transform infrared, fluorescence (i.e., emission fluorescence, synchronous fluorescence and fluorescence lifetime) and circular dichroism spectroscopy. The intermolecular interactions of HSA, HSAUV and HSAUV/H2O2 with NFLX were studied at pH 7.4 and temperatures 291, 310, and 318 K, using fluorescence emission and synchronous fluorescence spectroscopy, and combined with molecular docking. The results suggested that UV and ROS could destroy the α-helix of HSA and induce the loose of HSA structure, and the average fluorescence lifetimes of HSA decreased from 6.12 ns to 3.76 ns (HSAUV) and 3.40 ns (HSAUV/H2O2). The conformational changes of HSA caused by UV and ROS allowed NFLX to get access to more potential binding sites and promoted the binding affinity of HSA for NFLX, while the temperature stability of the HSA-NFLX complex significantly decreased. The results are useful and valuable for evaluating the protein damage caused by UV and ROS in organisms.

Using Human Serum Albumin Binding Affinities as a Proactive Strategy to Affect the Pharmacodynamics and Pharmacokinetics of Preclinical Drug Candidates.

We report on a new preclinical drug optimization strategy that measures drug candidates' binding affinity with human serum albumin (HSA) as an assessment of increasing or decreasing serum T1/2. Three common scaffolds were used as drug prototypes. Common polar and nonpolar substituents attached to the scaffolds have been identified as opportunities for increasing or decreasing the HSA binding affinity. This approach of adjusting HSA binding could be proactively established for preclinical drug candidates by appending functionality to sites on the drug scaffold not involved in biological target interactions. This strategy complements other medicinal chemistry efforts to identify longer or shorter human dosing regimens.

GZR18, a novel long-acting GLP-1 analog, demonstrated positive in vitro and in vivo pharmacokinetic and pharmacodynamic characteristics in animal models

GZR18 is a novel analog of glucagon-like peptide-1 (GLP-1). This study evaluates the pharmacology, pharmacokinetics, and efficacy of GZR18, and its potential for the treatment of Type 2 diabetes mellitus (T2DM). In vitro pharmacology and activity of GZR18 were characterized by a binding assay of GZR18 using human serum albumin (HSA), an activation assay in human GLP-1 receptor-expressing cell lines, and its effect on glucose-stimulated insulin secretion (GSIS) in primary mice islets. Pharmacokinetic profiling was performed in Sprague Dawley rats and cynomolgus monkeys, and efficacy evaluated using GZR18 single or repeated doses in db/db mice. GZR18 showed similar binding affinity for HSA and GLP-1 receptor compared with semaglutide and liraglutide. GZR18 increased GSIS, which was confirmed by dynamic islet perifusion and fluorescence imaging using PKZnR-5 for real-time detection. In cynomolgus monkeys, the average GZR18 maximal concentration was 527 nmol L−1, the terminal half-life (T1/2) was 61.3 h, and the time to maximum concentration was 14 h. Single-dose GZR18 lowered blood glucose levels and reduced body weight over 72 h in db/db mice. GZR18 successive administration (every three days for 33 days, i.e. 11 doses) lowered nonfasting and fasting blood glucose levels (p < 0.05 versus control) and glycated hemoglobin, following the 11th dose. Food and water consumption in db/db mice was lowered following repeated doses of GZR18 (p < 0.05 versus control), without a reduction in body weight. These results demonstrate the potential of GZR18 as a long-acting GLP-1 analog for the treatment of T2DM.

An Albumin-Binding PSMA Ligand with Higher Tumor Accumulation for PET Imaging of Prostate Cancer.

Prostate-specific membrane antigen (PSMA) is an ideal target for the diagnosis and treatment of prostate cancer. Due to the short half-life in blood, small molecules/peptides are rapidly cleared by the circulatory system. Prolonging the half-life of PSMA probes has been considered as an effective strategy to improve the tumor detection. Herein, we reported a 64Cu-labeled PSMA tracer conjugating with maleimidopropionic acid (MPA), 64Cu-PSMA-CM, which showed an excellent ability to detect PSMA-overexpressing tumors in delayed time. Cell experiments in PSMA-positive 22Rv1 cells, human serum albumin binding affinity, and micro-PET imaging studies in 22Rv1 model were performed to investigate the albumin binding capacity and PSMA specificity. Comparisons with 64Cu-PSMA-BCH were performed to explore the influence of MPA on the biological properties. 64Cu-PSMA-CM could be quickly prepared within 30 min. The uptake of 64Cu-PSMA-CM in 22Rv1 cells increased over time and it could bind to HSA with a high protein binding ratio (67.8 ± 1.5%). When compared to 64Cu-PSMA-BCH, 64Cu-PSMA-CM demonstrated higher and prolonged accumulation in 22Rv1 tumors, contributing to high tumor-to-organ ratios. These results showed that 64Cu-PSMA-CM was PSMA specific with a higher tumor uptake, which demonstrated that MPA is an optional strategy for improving the radioactivity concentration in PSMA-expressing tumors and for developing the ligands for PSMA radioligand therapy.

The evaluation of drug-plasma protein binding interaction on immobilized human serum albumin stationary phase, aided by different computational approaches

The drug-human serum albumin binding interaction was evaluated on a stationary phase immobilized with human serum albumin using a mixture of phosphate buffer (pH 7.0) and acetonitrile modifier as mobile phase. The 33 compounds that have a wide structural and therapeutic diversity were analyzed by performing a large number of experiments. The interaction mechanism was interpreted based on: i) retention characteristics of structurally related compounds, ii) retention modeling, iii) quantitative structure retention relationship (QSRR), and iv) molecular docking. Small structural differences of related compounds (e.g., reflected in different lipophilicity and polarity) have been found to affect their different binding to human serum albumin. It was found that drug retention in HSA column can be successfully described by using the quadratic function. The isocratic (logk(14%)) and extrapolated (b0(LSS)) retention factors showed the highest correlation (r > 0.76) with the constant that defines the binding affinity for human serum albumin (ACD/I-Lab). Therefore, selected chromatographic parameters can demonstrate reliable applicability for rapid screening of drug-plasma protein binding in drug discovery. In QSRR study, the resulting SVM/logk(14%) and MLR/b0(LSS) models display high internal and external predictive power. The constitutional properties (double bonds, aromatic rings, benzyl, allyl, -amino and -sulfur containing functional groups) supported by the charged parts of surface area had a significant impact on human serum albumin-binding affinity, which was also confirmed with molecular docking study. The high structural diversity of the data set provides wide applicability of tested chromatographic conditions and constructed models for defining the pharmacokinetic profile and possible structural modifications that can increase plasma protein binding of newly synthesized, pharmaceutically important compounds.

Changes in Glycated Human Serum Albumin Binding Affinity for Losartan in the Presence of Fatty Acids In Vitro Spectroscopic Analysis.

Conformational changes in human serum albumin due to numerous modifications that affect its stability and biological activity should be constantly monitored, especially in elderly patients and those suffering from chronic diseases (which include diabetes, obesity, and hypertension). The main goal of this study was to evaluate the effect of a mixture of fatty acids (FA) on the affinity of losartan (LOS, an angiotensin II receptor (AT1) blocker used in hypertension, a first-line treatment with coexisting diabetes) for glycated albumin—simulating the state of diabetes in the body. Individual fatty acid mixtures corresponded to the FA content in the physiological state and in various clinical states proceeding with increased concentrations of saturated (FAS) and unsaturated (FAUS) acids. Based on fluorescence studies, we conclude that LOS interacts with glycated human serum albumin (af)gHSA in the absence and in the presence of fatty acids ((af)gHSAphys, (af)gHSA4S, (af)gHSA8S, (af)gHSA4US, and (af)gHSA8US) and quenches the albumin fluorescence intensity via a static quenching mechanism. LOS not only binds to its specific binding sites in albumins but also non-specifically interacts with the hydrophobic fragments of its surface. Incorrect contents of fatty acids in the body affect the drug pharmacokinetics. A higher concentration of both FAS and FAUS acids in glycated albumin reduces the stability of the complex formed with losartan. The systematic study of FA and albumin interactions using an experimental model mimicking pathological conditions in the body may result in new tools for personalized pharmacotherapy.

Strategies to Maximize Anthracycline Drug Loading in Albumin Microbubbles.

Human serum albumin (HSA) microbubbles (MBs) are attracting increasing attention as image-guided and stimuli-responsive drug delivery systems. To better understand and maximize drug encapsulation in HSA MBs, we investigated the impact of the loading strategy and the drugs' physicochemical properties on their entrapment in the MB shell. Regarding loading strategy, we explored preloading, i.e., incubating drugs with HSA prior to MB formation, as well as postloading, i.e., incubating drugs with preformed MB. Both strategies were utilized to encapsulate six anthracyclines with different physicochemical properties. We demonstrate that drug loading in the HSA MB shell profits from preloading as well as from employing drugs with high intrinsic HSA binding affinity. These findings exemplify the potential of exploiting the natural bioconjugation interactions between drugs and HSA to formulate optimally loaded MBs, and they promote the development of HSA MBs for ultrasound-triggered drug delivery.

Multispectroscopic and molecular modeling strategy to explore the interaction of cholest-5-en-7-one with human serum albumin: DFT and Hirshfeld surface analysis

The present study accounts for cholest-5-en-7-one (steroid) synthesis using selenium dioxide and silica as well as its identification using high-resolution mass spectrometry (HRMS), FT-IR, NMR, and elemental analysis. Density functional theory (DFT) calculations were used to optimize the steroid's geometry, which was then compared to single-crystal X-ray diffraction data, indicating that the computational and experimental results were in good agreement. UV–vis absorption titration, fluorescence spectral methods, circular dichroism (CD), and dynamic light scattering (DLS)were used to investigate the well-identified steroid's in vitro molecular interaction with human serum albumin (HSA).The results and binding parameter indicate that the steroid has significant binding affinity for HSA. Molecular docking was performed and found that the steroid can interact with the hydrophobic cavity of HSA through hydrogen and hydrophobic contacts. Molecular dynamics simulation was used to confirm the stability of the HSA-steroid complex. Combined quantum mechanics-molecular mechanics (QM-MM) methods were applied to know binding energy of system and individual components for atomic level interactions indicating a significant interaction between the steroid and the biomacromolecules. The findings presented here contribute to a better understanding of steroid pharmacodynamics.

Insights into graphene oxide interaction with human serum albumin in isolated state and in blood plasma

The interactions of graphene oxide (GO), a 2-dimensional nanomaterial with hydrophilic edges, hydrophobic basal plane and large flat surfaces, with biological macromolecules, are of key importance for the development of novel nanomaterials for biomedical applications. To gain more insight into the interaction of GO flakes with human serum albumin (HSA), we examined GO binding to HSA in its isolated state and in blood plasma. Calorimetric data reveal that GO strongly stabilizes free isolated HSA against a thermal challenge at low ionic strength, indicating strong binding interactions, confirmed by the drop in ζ-potential of the HSA/GO assemblies compared to bare GO flakes. However, calorimetry also revealed that the HSA-GO molecular interaction is hampered in blood plasma, the ionic strength being particularly important for the interactions. Molecular modelling calculations are in full concert with these experimental findings, indicating a considerably higher binding affinity for HSA to GO in its partially unfolded state, characteristic to low-ionic-strength environment, than for the native protein conformation, observed under physiological conditions. Therefore, for the first time we demonstrate an impeded interaction between HSA and GO nanoflakes in blood plasma, and suggest that the protein is protected from the plausible toxic effects of GO under native conditions.

Anionic versus neutral Pt(II) complexes: The relevance of the charge for human serum albumin binding

The focus of this work is pointing out the different behavior of two structurally related Pt(II) complexes, the anionic cyclometalated NBu4[(Bzq)Pt(Thio)], 1 and the neutral [(Phen)Pt(Thio)], 2, (Bzq = benzo[h]quinoline, Phen = 1,10-phenantroline, Thio = 1,2-benzenedithiolate), on the interaction with human serum albumin (HSA), a key drug-delivery protein in the bloodstream. Being very limited the number of anionic Pt(II) complexes reported to date, this is a pioneering example of report on a protein-ligand interaction involving a negatively charged platinum compound. The study was carried out by using fluorescence spectroscopy, differential scanning calorimetry and molecular docking simulations. The results revealed a strong binding affinity between the anionic compound and the protein, whereas a weak/moderate binding interaction was highlighted for the neutral one. Comparative studies with site specific ligands (warfarin and ibuprofen), allowed us to identify the protein binding sites of the two compounds.The work aims to shed light on the relevance of the charge in designing new drugs with a favorable binding affinity for HSA, which strongly contributes to influence their pharmacological and toxicological profile.

Human Serum Albumin Binding in a Vial: A Novel UV-pH Titration Method To Assist Drug Design.

The knowledge on human serum albumin (HSA) binding is of utmost importance as it affects pharmacokinetic behavior and bioavailability of drugs. In this article, we report a novel method to screen for ionizable molecules with high HSA binding affinity based on pKa shifts using UV-pH titration. We investigated the HSA binding of 27 drugs and compared the results to experimental data from conventional methods. In most cases, significant shifts (ΔpKa > 0.1) were observed for drugs with high HSA binding, while no change could be detected for low-affinity binders. We showed the pivotal role of ionization centers in the formation of strong interactions between drug and HSA using molecular docking studies. We also verified our findings by testing five modified analogues designed by structural considerations. Significant decreases in their HSA binding proved that the UV-pH titration method combined with an in silico support can be used as a medicinal chemistry tool to assist rational molecular design.

Pharmacologically bio-relevant N-functionalized homo-binuclear macrocyclic complexes: synthesis, spectral studies, biological screening, HSA binding, and molecular docking

The bio-efficient homobinuclear macrocyclic complexes, [Co2LCl4] · 2H2O (1), [Ni2LCl4] · 2H2O (2), [Cu2LCl4] (3) and [Zn2LCl4] · H2O (4); Tetrachloro[1,1' biphenyl bis(1,6,9,14-tetrahydro-3,4;11,12-diphenyl-1,6,9,14-tetraazacyclohexadecane)] di metal(II).nH2O, were synthesized via metal ion controlled reaction using 3,3′-diaminobenzidine, 1,2-bis(bromomethyl)benzene and ethane-1,2-diamine. The stoichiometry, geometry, thermal stability and morphology of the synthesized compounds were inferred by analytical and spectral data. The complex 3 showed substantial radical scavenging potency. The metal complexes were also screened for comparative antibacterial analysis against different pathogenic microbes. XTT reduction assay further certified this observation to resist biofilm formation. Further, various biophysical measurements were performed for the assessment of human serum albumin-binding affinity of complexes 1-4.

Multispectroscopic insight, morphological analysis and molecular docking studies of CuII-based chemotherapeutic drug entity with human serum albumin (HSA) and bovine serum albumin (BSA)

The interaction studies of CuII nalidixic acid–DACH chemotherapeutic drug entity, [C36H50N8O6Cu] with serum albumin proteins, viz., human serum albumin (HSA) and bovine serum albumin (BSA) employing UV–vis, fluorescence, CD, FTIR and molecular docking techniques have been carried out. Complex [C36H50N8O6Cu] demonstrated strong binding affinity towards serum albumin proteins via hydrophobic contacts with binding constants, K = 3.18 × 105 and 7.44 × 104 M–1 for HSA and BSA, respectively implicating a higher binding affinity for HSA. The thermodynamic parameters ΔG, ΔH and ΔS at different temperatures were also calculated and the interaction of complex [C36H50N8O6Cu] with HSA and BSA was found to be enthalpy and entropy favoured, nevertheless, complex [C36H50N8O6Cu] demonstrated higher binding affinity towards HSA than BSA evidenced from its higher binding constant values. Time resolved fluorescence spectroscopy (TRFS) was carried out to validate the static quenching mechanism of HSA/BSA fluorescence. The collaborative results of spectroscopic studies indicated that the microenvironment and the conformation of HSA and BSA (α–helix) were significantly perturbed upon interaction with complex [C36H50N8O6Cu]. Hirshfeld surfaces analysis and fingerprint plots revealed various intermolecular interactions viz., N–H····O, O–H····O and C–H····O linkages in a 2–dimensional framework that provide crucial information about the supramolecular architectures in the complex. Molecular docking studies were carried out to ascertain the preferential binding mode and affinity of complex [C36H50N8O6Cu] at the target site of HSA and BSA. Furthermore, only for Transmission electroscopy microscopy micrographs of HSA and BSA in presence of complex [C36H50N8O6Cu] revealed major protein morphological transitions and aggregation which validates efficient delivery of complex by serum proteins to the target site.Communicated by Ramaswamy H. Sarma

Binding modes of environmental endocrine disruptors to human serum albumin: insights from STD-NMR, ITC, spectroscopic and molecular docking studies

Given that bisphenols have an endocrine-disrupting effect on human bodies, thoroughly exposing their potential effects at the molecular level is important. Saturation transfer difference (STD) NMR-based binding studies were performed to investigate the binding potential of two bisphenol representatives, namely, bisphenol B (BPB) and bisphenol E (BPE), toward human serum albumin (HSA). The relative STD (%) suggested that BPB and BPE show similar binding modes and orientations, in which the phenolic rings were spatially close to HSA binding site. ITC analysis results showed that BPB and BPE were bound to HSA with moderately strong binding affinity through electrostatic interactions and hydrogen bonds. The order of binding affinity of HSA for two test bisphenols is as follows: BPE > BPB. The results of fluorescence competitive experiments using 5-dimethylaminonaphthalene-1-sulfonamide and dansylsarcosine as competitors, combined with molecular docking indicated that both bisphenols are prone to attach to the binding site II in HSA. Spectroscopic results (FT-IR, CD, synchronous and 3D fluorescence spectra) showed that BPB/BPE induces different degrees of microenvironmental and conformational changes to HSA.

Molecular interaction study of flavonoids with human serum albumin using native mass spectrometry and molecular modeling.

Noncovalent interactions between proteins and small-molecule ligands widely exist in biological bodies and play significant roles in many physiological and pathological processes. Native mass spectrometry (MS) has emerged as a new powerful tool to study noncovalent interactions by directly analyzing the ligand-protein complexes. In this work, an ultrahigh-resolution native MS method based on a 15-T SolariX XR Fourier transform ion cyclotron resonance mass spectrometer was firstly used to investigate the interaction between human serum albumin (HSA) and flavonoids. Various flavonoids with similar structure were selected to unravel the relationship between the structure of flavonoids and their binding affinity for HSA. It was found that the position of the hydroxyl groups and double bond of flavonoids could influence the noncovalent interaction. Through a competitive experiment between HSA binding site markers and apigenin, the subdomain IIA (site 1) of HSA was determined as the binding site for flavonoids. Moreover, a cooperative allosteric interaction between apigenin and ibuprofen was found from their different HSA binding sites, which was further verified by circular dichroism spectroscopy and molecular docking studies. These results show that native MS is a useful tool to investigate the molecular interaction between a protein and its ligands. Graphical abstract Unravel the relationship between the structure of flavonoids and their binding affinity to HSA by native MS.

Impact of geometry optimization methods on QSAR modelling: A case study for predicting human serum albumin binding affinity

Quantitative structure–activity relationship (QSAR) modelling is a major tool employed in the prediction of various endpoints. However, current QSAR literature is missing a full understanding of the impact of quantum chemical calculation methods on the estimation of molecular descriptors and model performance. Here, we provide a comprehensive analysis of the quantitative effects of different geometry optimization methods (semi-empirical, ab initio Hartee-Fock and density functional theory) on the molecular descriptors. Using experimental binding affinity to human serum albumin (HSA) data, we comparatively investigated the influence of employing descriptors derived from three calculation methods on the QSAR models. We propose a 4-descriptor QSAR model in line with the OECD validation principles for the prediction of drug binding affinity to HSA (log KHSA) as a potential tool for drug development. We also confirm the prediction capability of the proposed model on a heterogeneous external set of chemicals. Furthermore, we recommend an activity-independent rational approach for the selection of geometry optimization method for an improved QSAR model development.

Comparative study on the interaction of two binuclear Pt (II) complexes with human serum albumin: Spectroscopic and docking simulation assessments

Human serum albumin (HSA) principally tasks as a transport carrier for a vast variety of natural compounds and pharmaceutical drugs. In the present study, two structurally related binuclear Pt (II) complexes containing cis, cis-[Me2Pt (μ-NN) (μ-dppm) PtMe2] (1), and cis, cis-[Me2Pt(μ-NN)(μ dppm) Pt((CH2)4)] (2) in which NN=phthalazine and dppm=bis (diphenylphosphino) methane were used to investigate their interaction with HSA, using UV–Vis absorption spectroscopy, fluorescence, circular dichroism and molecular dynamic analyses. The spectroscopic results suggest that upon binding to HSA, the binuclear Pt (II) complexes could effectively induce structural alteration of this protein. These complexes can bind to HSA with the binding affinities of the following order: complex 2>complex 1. Moreover, the thermodynamic parameters of binding between these complexes and HSA suggested the existence of entropy-driven spontaneous interaction, which mostly dominated with the hydrophobic forces. The ANS fluorescence results also indicated that two binuclear Pt (II) complexes were competing for the binding to the hydrophobic regions on HSA. In addition, competitive displacement assay and docking simulation study revealed that complexes 1 and 2 bind to the drug binding sites II and I on HSA, respectively. Furthermore, complex 2, with the higher binding affinity for HSA, shows more denaturing effect on this protein. Considering the protein structural damages in the pathway of harmful side effects of platinum drugs, complex 1 with the moderate binding affinity and low denaturing effect might be of high significance.

Synthesis, characterization and separation of chiral and achiral diastereomers of Schiff base Pd(II) complex: A comparative study of their DNA- and HSA-binding

A racemic mixture of a new chiral Schiff base ligand (HL: R/S-(1-phenylethylimino)methylnaphtalen-2-ol) has been utilized to prepare Pd(II) complex. Crystallization technique has been employed to separate diastereomeric pairs of Pd(II) complex: (mesoPdL2) and (racPdL2) that in this paper are known as PdL21 and PdL22, respectively. The synthesized complexes have been characterized by means of elemental analysis (CHN), FT-IR, 1H and 13C NMR spectroscopies. Moreover, PdL21 has been structurally characterized by single-crystal X-ray diffraction. The geometry around the metal center is square-planar. The interaction of two diastereomers of Pd(II) complex with FS-DNA has been explored, using UV–vis spectroscopy, fluorescence quenching, chemometrics and viscosity measurement methods. The PdL21 exhibited higher binding constant, about 10-fold, (1.0×106M−1) as compared to PdL22 (1.51.5×105M−1). Moreover, the human serum albumin (HSA) binding ability has been monitored by absorption, quenching of tryptophan fluorescence emission and circular dichroism (CD) studies. The slight difference is observed between HSA binding affinity with the complexes: PdL21 (6.2×104M−1) and PdL22 (3.3×104M−1). Also, the thermodynamic parameters were determined at three different temperatures (298, 308 and 318K).In this study, molecular docking was also carried out to confirm and illustrate the specific DNA- and HSA-binding of the Pd(II) complexes. In the PdL21-HSA system a T-shaped π-π interaction with PHE206 was observed. While in the PdL22-HSA system there are a hydrogen bond, a π-cation and two T-shaped π-π interactions with ASB324, LYS212 and PHE228, respectively. The groove binding mode of DNA interaction has been proposed for both diastereomers.

Ischemia Modified Albumin –An Early Marker of Myocardial Ischemia

INTRODUCTION Myocardial Ischemia occurs when there is an inadequate supply of blood to the myocardium resulting in an imbalance between myocardial oxygen supply and demand. The most common cause of Myocardial ischemia is an atherosclerotic disease of an epicardial coronary artery leading to a regional reduction in myocardial blood flow, followed by spasm, arterial thrombi, and rarely coronary emboli. Episodes of defective perfusion result in decreased myocardial tissue oxygen tension, and cause transient disturbance of mechanical, biochemical and electrical functions of the myocardium. More severe the block, more the damage to the myocardium, also in relation to the duration of oxygen supply. Early diagnosis of Myocardial Infarction at this stage itself can prevent morbidity and mortality. Though we have various myocardial proteins in the serum like CK-MB, LDH, AST and Troponins I and T for diagnosing Acute Myocardial Infarction, along with ECG, we should be able to identify myocardial ischemia before it progresses to irreversible myocardial cell damage. These markers are not elevated in the absence of necrosis when measured in the first 2 to 6 hours following an ischemic event. The present study on ischemia modified albumin has been found to be very useful for the detection of myocardial ischemia within 6 hours of onset of chest pain. Ischemia Modified Albumin (IMA) is measured by Albumin Cobalt Binding assay. It is based on the reduced binding affinity of human serum albumin for metal ions like Cobalt attributed to the free radical damage to the N - terminal region of albumin in patients with myocardial ischemia. The values are correlated with CK-MB and lipid profile. AIM OF THE STUDY : Aim of the study is to measure the Ischemia Modified Albumin by Albumin Cobalt Binding assay in patients, within 6 hours of onset of chest pain. OBJECTIVE : (1) To correlate the IMA values with CK-MB (2) Correlation of other markers of atherosclerosis like: (a) Total cholesterol, (b) Triacylglycerol, (c) High density lipoprotein, (d) Low density lipoprotein, (e) Very low density lipoprotein with IMA, (3) To prove the use of IMA as an early marker of myocardial ischemia. CONCLUSION : Biochemical markers such as CK-MB, Cardiac Troponin-I and Myoglobin are suitable only for assessing myocardial infarction. The results of the present study confirm the findings of previous studies, that reported that the Albumin Cobalt colorimetric assay distinguishes myocardial ischemic patients from non ischemic patients (p<0.001) Introduction of IMA assay for the first time provides emergency physicians with an objective diagnostic study to determine the presence of myocardial ischemia completely within the control of the emergency department. IMA assay presents a quantitative accurate laboratory determination of the occurrence of an Ischemic myocardial event, Angina of various types. Unlike the previous laboratory parameters that identify myocardial damage, only after it is well established, this test (Albumin Cobalt binding assay) helps to determine which patients will go in for severe occlusion. The introduction of IMA is a welcome event and based on the results obtained, the present study supports the hypothesis that Ischemia Modified Albumin is a useful marker for the early diagnosis of myocardial ischemia before any significant increase in CK-MB levels.