13 research outputs found

    Computer-aided Design of Chalcone Derivatives as Lead Compounds Targeting Acetylcholinesterase

    Get PDF
    One of well-established biological activities for chalcone derivatives is as acetylcholinesterase inhibitors, which can be developed for the therapy of Alzheimer’s disease. Assisted byretrospectively validated structure-based virtual screening (SBVS) protocol to identify potent acetylcholinesterase inhibitors, 80chalcone derivatives were designed and virtually screened. The F-measure value as the parameter of the predictive ability of the SBVS protocol developed in the research presented in this article was 0.413, which was considerably better than the original SBVS protocol (F-measure = 0.226). Among the screened chalcone derivatives two were selected as potential lead compounds to designpotent inhibitors for acetylcholinesterase: 3-[4-(benzyloxy)-3-methoxyphenyl]-1-(4-hydroxy-3-methoxyphenyl)prop-2-en-1-one(3k) and 3-[4-(benzyloxy)-3-methoxyphenyl]-1-(4-hydroxyphenyl)prop-2-en-1-one (4k)

    Structural insights into the agonists binding and receptor selectivity of human histamine H₄ receptor

    Get PDF
    慢性アレルギー疾患に関わるヒスタミン受容体の構造解明 --新規アトピー性皮膚炎・喘息治療薬の開発に貢献--. 京都大学プレスリリース. 2023-10-23.Histamine is a biogenic amine that participates in allergic and inflammatory processes by stimulating histamine receptors. The histamine H₄ receptor (H₄R) is a potential therapeutic target for chronic inflammatory diseases such as asthma and atopic dermatitis. Here, we show the cryo-electron microscopy structures of the H₄R-Gq complex bound with an endogenous agonist histamine or the selective agonist imetit bound in the orthosteric binding pocket. The structures demonstrate binding mode of histamine agonists and that the subtype-selective agonist binding causes conformational changes in Phe344[7.39], which, in turn, form the “aromatic slot”. The results provide insights into the molecular underpinnings of the agonism of H₄R and subtype selectivity of histamine receptors, and show that the H₄R structures may be valuable in rational drug design of drugs targeting the H₄R

    Structure-Based Prediction of Subtype Selectivity of Histamine H_3 Receptor Selective Antagonists in Clinical Trials

    Get PDF
    Histamine receptors (HRs) are excellent drug targets for the treatment of diseases, such as schizophrenia, psychosis, depression, migraine, allergies, asthma, ulcers, and hypertension. Among them, the human H_3 histamine receptor (hH3HR) antagonists have been proposed for specific therapeutic applications, including treatment of Alzheimer’s disease, attention deficit hyperactivity disorder (ADHD), epilepsy, and obesity. However, many of these drug candidates cause undesired side effects through the cross-reactivity with other histamine receptor subtypes. In order to develop improved selectivity and activity for such treatments, it would be useful to have the three-dimensional structures for all four HRs. We report here the predicted structures of four HR subtypes (H_1, H_2, H_3, and H_4) using the GEnSeMBLE (GPCR ensemble of structures in membrane bilayer environment) Monte Carlo protocol, sampling ~35 million combinations of helix packings to predict the 10 most stable packings for each of the four subtypes. Then we used these 10 best protein structures with the DarwinDock Monte Carlo protocol to sample ~50 000 × 10^(20) poses to predict the optimum ligand–protein structures for various agonists and antagonists. We find that E206^(5.46) contributes most in binding H3 selective agonists in agreement with experimental mutation studies. We also find that conserved E5.46/S5.43 in both of hH_(3)HR and hH_(4)HR are involved in H_(3)/ H_(4) subtype selectivity. In addition, we find that M378^(6.55) in hH_(3)HR provides additional hydrophobic interactions different from hH_(4)HR (the corresponding amino acid of T323^(6.55) in hH_(4)HR) to provide additional subtype bias. From these studies, we developed a pharmacophore model based on our predictions for known hH_(3)HR selective antagonists in clinical study [ABT-239 1, GSK-189,254 2, PF-3654746 3, and BF2.649 (tiprolisant) 4] that suggests critical selectivity directing elements are: the basic proton interacting with D114^(3.32), the spacer, the aromatic ring substituted with the hydrophilic or lipophilic groups interacting with lipophilic pockets in transmembranes (TMs) 3–5–6 and the aliphatic ring located in TMs 2–3–7. These 3D structures for all four HRs should help guide the rational design of novel drugs for the subtype selective antagonists and agonists with reduced side effects

    Enhancing the fight against malaria : from genome to structure and activity of a G-protein coupled receptor from the mosquito, Anopheles Gambiae

    Get PDF
    Includes abstract.Includes bibliographical references (leaves 183-184).G-proton coupled receptors (GPCRs) are excellent drug targets that occupy a central position in the physiology of insects and are involved in transmission of signal from the extracellular to the intracellular side of the cell. Adipokinetic hormone receptors (AKHRs) are GPCRs that mediate physiological functions of the neurohormones, adipokinetic hormones (AKHs) that regulate mobilisation of energy reserves during mosquito flight. Ligand binding to GPCRs depends on the three dimensional (3D) structures of the receptors but to date no crystal structures of insect GPCRs are available. This work focused on building molecular models of AKHR from the genome of the malaria mosquito, identifying its binding site and studying the conformational and structural changes during molecular dynamics of the active and inactive receptor

    Characterisation of the α1B-adrenoceptor by modeling, dynamics and virtual screening

    Get PDF

    Klonierung und pharmakologische Charakterisierung des equinen Histamin H4 Rezeptors

    Get PDF
    In the present study, the equine histamine 4 receptor (eH4R) was cloned, sequenced and pharmacologically characterized. The findings were compared to those, obtained with the human H4R (hH4R). Due to its expression in cells of the immune system, the eH4R provides a promising target for the development of novel therapeutic strategies in allergic diseases, such as Recurrent Airway Obstruction (RAO) and allergic dermatitis in the horse. To clone the eH4R, mRNA was isolated from horse white blood cells and cDNA was synthesized by reverse transcription. Specific primers were used to amplify the eH4R sequence, which was then cloned into pJET1.2/blunt vectors. The open reading frame is 1185 bp long and codes for a 394 amino acid protein which shows 72,9 % homology to the human receptor. The cDNA sequence was published in the NCBI GenBank under the accession number HM015200. To pharmacologically and functionally characterize the eH4R and hH4R, their cDNAs were subcloned into the expression vector pcDNA3.1 and either transfected transiently into COS-7 cells or stably into HEK293 cells. Binding-characteristics were examined by homologous und heterologous competition experiments using the antagonist 3H-pyrilamine or the agonist 3H-histamine as radioligand. High affinity binding of histamine could only be detected in hH4R, but not in eH4R transfected COS-7 cells. Nevertheless, histamine was able to inhibit cAMP-production in stably transfected HEK293 cells via the eH4R and the hH4R. The eH4R expressed in HEK293 cells is coupled to the stimulation of ERK1/2, while the hH4R shows already high constitutive activity. The antagonists JNJ7777120, Thioperamide, Pyrilamine and Diphenhydramine display considerable species-specific differences concerning the affinities between eH4R and hH4R and also vary in their intrinsic activities. Thioperamide, known for its inverse agonism at the hH4R showed agonist behaviour in ERK1/2 regulation. In contrast, the non-selective antagonist Diphenhydramin showed inverse agonist behaviour, which was more pronounced at the hH4R than the eH4R. These findings suggest that there are considerable pharmacological and functional differences between the cloned eH4R and hH4R

    Development of a pseudoreceptor model for virtual screening

    Get PDF
    Im Rahmen dieser Arbeit wurde die Eignung von Pseudorezeptoren im virtuellen Screening untersucht. Hierzu wurde nach intensiver Auseinandersetzung mit bisher bekannten Konzepten ein neues Computerprogramm zur automatischen Konstruktion von Pseudorezeptormodellen entwickelt. Das Ziel von Pseudorezeptoren ist die Konstruktion eines alternativen, artifiziellen Wirtssystems aus bekannten Liganden eines Zielproteins, dessen dreidimensionale Struktur unbekannt ist. Der generierte Pseudorezeptor ist zu verstehen als die Menge aller Pseudoatome, die um die Ausgangssubstanz(en) projiziert werden. Bei multiplen Referenzliganden wird eine Gewichtung der Pseudoatome durchgeführt. Zudem wird ausschließlich von Distanz- und Winkelparametern Gebrauch gemacht, die aus Untersuchungen von Kokristall-strukturen gewonnenen wurden. Eine abschließende Kodierung generierter Pseudorezeptoren als 90-dimensionalen Korrelationsvektor wurde zum virtuellen Screening eingesetzt. In zwei retrospektiven Fallbeispielen wird gezeigt, dass die generierten Pseudorezeptoren für COX-2 und PPARα mit den realen Zuständen ihrer kokristallisierten Bindetaschen in den PDB Einträge 6cox und 2p54 kompatibel sind. Im retrospektiven virtuellen Screening in der Wirkstoffdatenbank COBRA (8.311 Moleküle) nach COX-2 Inhibitoren (136 Aktive) konnte eine Anreicherung der aktiven Strukturen in den ersten zwei Perzentilen gezeigt werden (54% der Aktiven). Zudem konnten 80% der aktiven Moleküle bereits nach Vorhersage von 10% Falsch-Positiven gefunden werden. Im Falle des retrospektiven Screenings nach 94 PPAR Liganden konnten 30% der aktiven Moleküle nach der Vorhersage von 10% Falsch-Positiven entdeckt. Nach 20% Falsch-Positiver wurden 46% der PPAR Liganden wieder gefunden. Weiterhin konnte mit den ligandenbasierten Informationen eines H4 Pseudorezeptors eine Justierung einer potentiellen Bindetasche des Histamin H4 Rezeptors aus einer molekularen Dynamiksimulation vorgenommen werden. Schließlich wurde in einem prospektiven virtuellen Screening nach Histamin H4 Liganden mit einem Pseudorezeptor zwei Strukturen mit unterschiedlichem Grundgerüst und einem Ki ~ 30 µM identifiziert.In this thesis, the suitability of pseudoreceptors for virtual screening applications was analyzed. An automated pseudoreceptor construction program was developed after known design principles had been thoroughly studied and compared. The aim of pseudoreceptor modelling is the construction of an alternative host system for known ligands of a given target protein in the absence of three-dimensional structure information. The constructed pseudoreceptor is represented as the sum of all pseudoatoms, which are projected around reference ligand(s). A weighting scheme is introduced, when pseudoreceptors are generated from multiple reference ligands. For pseudoatom placing distance and angle parameters from a survey of known co-crystal structures were used. For virtual screening pseudoreceptors were encoded as correlation vectors. It is demonstrated that the generated pseudoreceptors match with their respective co- crystallized binding pockets, taking COX-2 and PPAR-alpha as an example (PDB entries 6cox and 2p54). In a retrospective virtual screening in the drug collection COBRA (8,311 molecules) for COX-2 inhibitors (136 actives) high enrichment of ligands in the first two percentiles was yielded (54% of the actives). 80% of all active compounds were found after the prediction of only 10% false-positives. In a retrospective screening study for 94 PPAR ligands, 30% of the actives were found together with 10% false-positives. After the prediction of 20% false-positives, 46% of all PPAR ligands could be found. In addition, a putative binding pocket of the histamine H4 receptor from a molecular dynamics simulation could be adjusted using ligand-based information of a H4 pseudoreceptor. Finally, two micromolar ligands with different scaffolds were identified with a Ki ~ 30 µM by a pseudoreceptor-based prospective virtual screening for novel H4 ligands
    corecore