Search Results (194)

Serotonin receptors, in particular 5-HT_1A and 5-HT_2A receptors, are important molecular targets for the central nervous system (CNS) disorders, such as schizophrenia, depression, anxiety disorders, memory deficits, and many others. Here, we present structural and pharmacological evaluation of a serotonin receptor ligand, SERAAK2, identified in a structure-based virtual screening campaign. Molecular docking studies revealed that SERAAK2 binds with its molecular targets via Asp3.32 as the main anchoring point, which is typical for orthosteric ligands of aminergic GPCRs. Molecular dynamics simulations confirmed the stability of the ligand binding poses in the studied receptors. MMGBSA calculations were in accordance with the receptor in vitro binding affinity studies, which indicated that SERAAK2 is a potent ligand of 5-HT_1A and 5-HT_2A receptors. It was also found that SERAAK2 displays favorable ADMET parameters. The demonstrated anxiolytic- and antidepressant-like effects of SERAAK2 in animal models, which may involve its interaction with 5-HT_1A receptors, warrant further studies to confirm these activities and elucidate the underlying mechanisms. Full article

Serotonin (5-HT) is a vital intercellular messenger with diverse signaling functions throughout the human body. We have characterized and implemented a novel, in vitro fluorescence-based method of measuring 5-HT binding to gain a fuller understanding of the interactions between 5-HT and its receptors. This method involves expression of 5-HT receptor proteins in cultured cells with the fluorescent, non-canonical amino acid l-3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (ANAP) incorporated into the ligand binding site. ANAP fluorescence was quenched in solution by both 5-HT and dopamine. Time-resolved photoluminescence and transient absorption spectroscopy confirmed that ANAP quenching by 5-HT occurs via a charge-transfer process that recovers through back-electron transfer on the nanosecond timescale. Supported by density functional theory calculations, this process likely involved an ANAP reduction by 5-HT. To test this method on intact receptors in a cellular context, we expressed 5-HT_3A receptors (5-HT-gated ion channels) in HEK293T cells with ANAP inserted co-translationally into the transmitter binding site. Fluorescently labeled 5-HT_3A receptors were functional and activated by 5-HT, as assessed by whole-cell patch clamp. Addition of 5-HT caused a concentration-dependent quenching of fluorescence from ANAP-tagged channels in intact cells and unroofed plasma membranes, demonstrating the utility of this method for measuring 5-HT binding to its receptors. Collectively, these results delineate a technique for measuring transmitter binding that can be widely adopted to explore 5-HT binding not only to 5-HT₃ receptors, but to any 5-HT receptor, transporter, or binding protein in heterologous expression systems. Full article

Background/Objectives: The study aimed to pharmacologically evaluate dually acting ligands, 5-HT₇ antagonists and sodium channel inhibitors, as potential therapeutic agents for the treatment of depression, anxiety, and neuropathic pain. The designed dual ligands combined structural fragments of LP-12 (a 5-HT₇ receptor ligand) and phenytoin (a sodium channel blocker). Methods: A series of 1-(2-biphenyl)piperazine derivatives with a hydantoin core was synthesized and evaluated for 5-HT₇ receptor affinity and sodium channel inhibition. The most potent ligands were further analyzed using molecular docking, cytotoxicity assays (MTT, LDH), and in vitro metabolism studies, including microsomal stability and CYP450 inhibition. In vivo pharmacological effects were assessed in behavioral models: forced swim test, four-plate test, and a streptozotocin (STZ)-induced diabetic neuropathy model in mice. Results: Compounds 10 and 20 exhibited high 5-HT₇ receptor affinity (K_i < 10 nM) and potent sodium channel inhibition (>80% at 1 µM). Docking studies revealed binding modes consistent with established 5-HT₇ ligands. Compound 10 showed lower cytotoxicity than compound 20 in both HepG2 and SH-SY5Y cells and was therefore selected for further evaluation. Metabolic profiling indicated improved microsomal stability relative to verapamil and a low risk of CYP-mediated drug–drug interactions. In vivo, compound 10 produced significant antidepressant- and anxiolytic-like effects, though it failed to reduce neuropathic pain symptoms in the STZ-induced model. Conclusions: Compound 10 shows potential for mood disorder treatment, but further refinement may be needed to improve analgesic efficacy. Full article

Autism spectrum disorder (ASD) is a neurodevelopmental condition marked by social/communication deficits and behavioral abnormalities, with neuronal apoptosis and immune-inflammatory dysregulation implicated in its pathogenesis. Marine-derived polysaccharides, particularly those from Enteromorpha prolifera (PEPs), exhibit neuroprotective and anti-inflammatory properties—yet their therapeutic potential for ASD remains unexplored. Major monosaccharide components of PEPs were identified as rhamnose, xylose, glucose, glucuronic acid, galactose, and ribose through ion chromatography analysis. Infrared spectroscopy confirmed PEPs as pyranose-type polysaccharides with α-glycosidic bonds and uronic acids, while gel permeation chromatography showed a predominant molecular weight of 3.813 kDa (83.919%). To explore the therapeutic potential of PEPs in ASD, a comprehensive method combining network pharmacology, molecular docking, and in vitro validation was conducted. A total of 235 ASD-related target proteins were predicted, with enrichment analyses indicating significant involvement in pathways such as neuroactive ligand–receptor interaction and the MAPK signaling pathway. In vitro assays using valproic acid (VPA)-induced HT22 neuronal cells showed that PEPs significantly attenuated apoptosis. Western blot analysis further confirmed the downregulation of HSP90AA1, cleaved CASP3/pro-CASP3, p-NF-κB1/NF-κB1, p-AKT1/AKT, and p-mTOR/mTOR, as well as the upregulation of IκBα after PEPs treatment. These findings suggest that PEPs exert neuroprotective effects through the modulation of apoptosis and inflammation-related signaling pathways, supporting their potential as a promising candidate for further study in ASD. Full article

The development of molecules that interact with G-quadruplex (G4) sequences requires effective evaluation methods. Several techniques are currently available, including nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography, surface plasmon resonance (SPR), isothermal titration calorimetry (ITC) and mass spectrometry (MS), fluorescence using FRET-melting, G4-fluorescent intercalator displacement assay (G4-FID) and affinity chromatography. Among these, CD spectroscopy is gaining prominence due to its lower material requirements, faster experimentation and quicker data processing. However, conventional CD methods have limitations, such as higher sample volume required and the inability to handle high-throughput analysis efficiently. The use of synchrotron radiation in high-throughput analysis methods (HT-SRCD) has further advanced the investigation of small-molecule interactions with DNA G4 structures in the presence of various monovalent cations. HT-SRCD offers the capability to analyze multiple samples simultaneously, overcoming the limitations of conventional CD methods. To validate this approach, three biologically relevant G4 sequences—HTelo1, G3T3 and T95-2T—were investigated. Their interactions with a library of small tetrazole-based molecules, synthesized via a four-component Ugi reaction, and with a peptide sequence deriving from RHAU helicases (Rhau25), were evaluated. The results demonstrate that this method not only effectively discriminates between different ligands but also provides valuable insights into the selectivity and the modes of interaction of these ligands with the G4 sequences. Full article

Background/Objectives: Neurotensin receptors (NTSRs), members of the G protein-coupled receptor (GPCR) family, have been found to be overexpressed in several types of human cancers, including breast, colon, lung, liver, prostate, and pancreatic cancer. In particular, NTSR1 is overexpressed in at least 75% of pancreatic ductal adenocarcinomas. The aim of the present study was the development and evaluation of new ^99mTc-labeled nonpeptide NTSR1-antagonists for SPECT imaging of NTSR-positive tumors. Methods: Multistep syntheses of NTSR1 antagonist derivatives were performed following our previously described procedure. Two different chelating strategies were applied for ^99mTc radiolabeling to provide the [^99mTc]Tc-HYNIC complex [^99mTc]1 and the [^99mTc]Tc-tricarbonyl complex [^99mTc]2. Receptor binding assays were performed using hNTSR1-expressing CHO cells. Radiochemical yields (RCYs) were determined by radio-HPLC. For [^99mTc]1 and [^99mTc]2, log D_7.4, plasma protein binding, stability in human plasma and serum, and cellular uptake in HT-29 cells were determined. Biodistribution studies and small animal SPECT studies were performed in HT-29 tumor-bearing nude mice. Results: The radiosynthesis of [^99mTc]1 (log D_7.4 = −0.27) and [^99mTc]2 (log D_7.4 = 1.00) was successfully performed with RCYs of 94–96% (decay-corrected). Both radioligands were stable in human serum and plasma, showed plasma protein binding of 72% ([^99mTc]1) and 82% ([^99mTc]2), and exhibited high and specific uptake in HT-29 cells. Biodistribution studies in HT-29 tumor-bearing mice showed a higher tumor accumulation of [^99mTc]1 compared to [^99mTc]2 (8.8 ± 3.4 %ID/g vs. 2.7 ± 0.2 %ID/g at 2 h p.i.). [^99mTc]2 showed exceptionally high intestinal accumulation (49 ± 22 %ID/g at 1 h p.i.) and was therefore considered unfavorable. In the SPECT/CT imaging of HT-29 tumor xenografts, [^99mTc]1 showed a higher NTSR1-specific tumor uptake than [^99mTc]2 at all time points after tracer injection, with 12 ± 2.8 %ID/g for [^99mTc]1 vs. 3.1 ± 1.1 %ID/g for [^99mTc]2 at 4 h p.i. and adequate tumor-to-background ratios. Conclusions: In particular, the [^99mTc]Tc-HYNIC ligand ([^99mTc]1) showed promising preclinical results, being a potential candidate for SPECT imaging and, therefore, appropriate for translation into the clinic. Full article

Many drug discovery efforts have identified potentially promising molecules; however, a common limitation of these reports is the lack of further experimental confirmation of pharmacokinetic properties and behavioral effects of discovered compounds. In this study, we aim to address this limitation. Therefore, we build on our previous virtual screening campaign by synthesizing, analyzing in silico, and evaluating experimentally the SERAAK1 compound, which was initially identified as a ligand for 5-HT_1A, 5-HT_2A, and D₂ receptors. Through these investigations, we discovered that SERAAK1 binds to the orthosteric pocket of the 5-HT_2A receptor in a similar mechanism to that known for marketed antipsychotic medications. Molecular dynamics simulations revealed that the SERAAK1 compound remains stable in the orthosteric binding pocket of the 5-HT_2A receptor. The determination of the ADMET parameters indicated the directions for further optimization of the compounds. In vivo studies demonstrated the anxiolytic and antidepressant properties of the SERAAK1 compound. Full article

In this study, a novel silver(I) complex [Ag(HL¹)₂]NO₃ (AgHL¹) with coumarin derivative (3E)-3-(1-{[(pyridin-2-yl)methyl]amino}ethylidene)-3,4-dihydro-2H-benzopyran-2,4-dione (HL¹) was prepared. The compounds HL¹ and AgHL¹ were characterized by IR and NMR spectroscopy, elemental analysis, and single crystal X-ray structural analysis. Specifically, the single crystal X-ray analysis determined the structures of both compounds HL¹ and AgHL¹ in their solid state, while NMR spectroscopy was used for structural determination in a solution. The HL¹ proved to be a monodentate ligand and is coordinated to the Ag(I) atom through a nitrogen atom from the 2-picolylamine fragment. In the complex AgHL¹, two molecules of neutral HL¹ are coordinated forming a nearly linear N-Ag-N arrangement. An uncoordinated nitrate anion balances the positive charge of the complex cation. NMR spectroscopy also confirmed the stability of AgHL¹ in DMSO-d₆ for 3 days. In vitro cytotoxicity of HL¹ and AgHL¹ was performed over two cancerous cell lines A549 and HT-29 and their selectivity was verified on a healthy CCD-18Co cell line. AgHL¹ exhibited low anticancer nonselective activity while the ligand was inactive. Also, the complex shows better antimicrobial activity than the positive controls on the Pseudomonas aeruginosa standard and clinical strain as well as on the tested molds. Full article

Three new complexes of copper(II) and chromone-2-carboxylic acid, a ligand from the group of hydroxypyrones, were synthesised according to the principles of green chemistry. The complexes were characterised by FT–IR and NMR spectroscopy, thermal and electrochemical analysis, and their structures are proposed. The results show the formation of mononuclear (1) and dinuclear hydroxo-bridged dinuclear copper(II) complexes (2 and 3). The results of cyclic voltammetry show that the copper in all complexes is in the +2-oxidation state. The antiproliferative activity was determined by MTT assay on 2D cell models in vitro on seven cell lines. The activity spectrum of complexes 1–3 ranged from the highest to the lowest value in the tumour cell lines tested, in the following order: Hep G2 > NCI-H358 > HT-29 > KATO III > MDA-MB 231 > Caco-2. The most effective concentration was 10⁻⁵ mol dm⁻³, which suppressed the growth of Hep G2 cells as follows: 69.5% (1), 64.8% (2) and 64% (3). The calculated selectivity index clearly shows that Hep G2 is the most sensitive cell line to copper complexes (SI = 1.623 (1); 1.557 (2), 1.431 (3). Full article

A series of 2- and 3-methoxyphenylpiperazine derivatives in combination with a 2-hydroxypropoxy linker and coumarins containing various substituents was synthesized and evaluated for antidepressant-like activity. Microwave-assisted synthesis was used, and the structures of all compounds were confirmed by ¹H, ¹³C NMR, and HRMS spectrometry. The affinity toward the 5-HT_1A and 5-HT_2A receptors was determined using radioligand binding assays and analyzed by molecular docking studies. Among the compounds evaluated, four demonstrated high affinity for the 5-HT_1A receptor with the following Ki values: 5-(2-hydroxy-3-(4-(2-methoxyphenyl)piperazin-1-yl)propoxy)-4,7-dimethyl-2H-chromen-2-one (5) (90 nM), 6-acetyl-5-(2-hydroxy-3-(4-(2-methoxyphenyl)piperazin-1-yl)propoxy)-4,7-dimethyl-2H-chromen-2-one (7) (90 nM), 7-(2-hydroxy-3-(4-(3-methoxyphenyl)piperazin-1-yl) propoxy)-4-methyl-2H-chromen-2-one (10) (87 nM), and 8-acetyl-7-(2-hydroxy-3-(4-(2-methoxy phenyl)piperazin-1-yl)propoxy)-4-methyl-2H-chromen-2-one (11) (96 nM), and four demonstrated high affinity for the 5-HT_2A receptor with the following Ki values: 6-acetyl-7-(2-hydroxy-3-(4-(3-methoxyphenyl)piperazin-1-yl)propoxy)-4-methyl-2H-chromen-2-one (2) (83 nM), 8-acetyl-7-(2-hydroxy-3-(4-(3-methoxyphenyl)piperazin-1-yl)propoxy)-4-methyl-2H-chromen-2-one (12) (67 nM), 7-(2-hydroxy-3-(4-(2-methoxyphenyl)piperazin-1-yl) propoxy)-2H-chromen-2-one (13) (18 nM), and 7-(2-hydroxy-3-(4-(3-methoxyphenyl)piperazin-1-yl)propoxy)-2H-chromen-2-one (14) (68 nM). In functional assays, 8-acetyl-7-(2-hydroxy-3-(4-(2-methoxyphenyl) piperazin-1-yl)propoxy)-4-methyl-2H-chromen-2-one (compound 11) exhibited a significant 5-HT_1A antagonistic profile. Computational studies revealed the structural details responsible for the high affinity of selected derivatives, which were compared to known 5HT_1A partial agonists. Full article

Background: Schizophrenia manifests through behavioral abnormalities, suicidal ideation, and neuropsychological deficits. Hence, this study focused on 5-hydroxytryptamine (5-HT 2C) which influenced the modulation of the series of events that lead to schizophrenia. Methodology: Based on the computational study, the potential 5-HT 2C inhibitors such as Ephemeranthoquinone from Arundina graminifolia and Actinodaphnine from Litsea polyantha were determined. The candidate ligands were optimized using the Gaussian 16 software package and the DFT 6-31g (d,p) basis set. The interaction between the ligands and proteins was examined with PyRx 0.8. Additionally, pharmacokinetics was assessed using SwissADME, and Protox II for toxicity prediction. The network pharmacology study was examined by using the STRING database and the Cytoscape 3.10.1 tool. Moreover, a 100-nanosecond molecular dynamics simulation analysis using Desmond to ensure the stability of these two compounds was carried out. Result: This computational research observed that ephemeranthoquinone and actinodaphnine are the most selective 5-HT 2C inhibitors due to their docking score, optimization, and molecular dynamics simulation results. Conclusions: These compounds are required to be studied further to develop a useful 5-HT 2C inhibitors for the treatment of schizophrenia. Full article

This study investigates the structural, vibrational, and biological properties of novel palladium(II) and platinum(II) complexes with 5-chloro-7-azaindole-3-carbaldehyde (5ClL) and 4-chloro-7-azaindole-3-carbaldehyde (4ClL) ligands. Infrared and Raman spectroscopy, combined with DFT (ωB97X-D) calculations, provided valuable information about metal–ligand interactions, the cis or trans conformation of the aldehyde group in the ligands, and the presence of trans isomers in the metal complexes obtained in the solid state. In vitro tests were used to evaluate the antiproliferative activity of the novel complexes against several cancer cell lines, including ovarian cancer (A2780), cisplatin-resistant ovarian cancer (A2780cis), colon cancer (HT-29), and triple-negative breast cancer (MDA-MB-231), as well as normal mouse fibroblasts (BALB/3T3). The platinum complex, trans-[PtCl₂(5ClL)₂], exhibited superior activity against A2780cis (IC₅₀ = 4.96 ± 0.49 µM) and MDA-MB-231 (IC₅₀ = 4.83 ± 0.38 µM) compared to cisplatin, while the palladium complexes (trans-[PdCl₂(4ClL)₂] and trans-[PdCl₂(5ClL)₂]) demonstrated enhanced selectivity with reduced toxicity to normal fibroblasts (IC₅₀ = 11.29 ± 6.65 µM and 14.98 ± 5.59 µM, respectively). Full article

Background: A phthalimide-functionalized heptamethine cyanine dye, named Ph790H, is used for targeted photothermal cancer therapy in vivo. We highlight that the chemical structure of Ph790H is newly designed and synthesized for the first time in this study. Objectives: By possessing a rigid chloro-cyclohexenyl ring in the heptamethine cyanine backbone, the bifunctional near-infrared (NIR) fluorescent dye Ph790H can be preferentially accumulated in tumor without the need for additional targeting ligands, which is defined as the “structure-inherent tumor targeting” concept. Methods: The phototherapeutic effect of Ph790H is evaluated in HT-29 human colorectal cancer xenografts to be used as a cancer-targeting photothermal agent. Results: The results reveal that the Ph790H shows enhanced tumor accumulation in HT-29 xenografts 48 h post-injection with a high tumor-to-background ratio. After determination of the optimal timing for photothermal therapy (PTT), the HT-29 tumor-possessing nude mice pretreated with Ph790H are subsequently irradiated with an 808 nm NIR laser for 5 min. The tumor-targeted PTT treatment can efficiently inhibit the tumor development compared with that of control groups. Moreover, no tumor regrowth or Ph790H-induced mortality occurs after the treatment of Ph790H and laser irradiation during a period of monitoring. Conclusions: Therefore, this work demonstrates that the bifunctional phototheranostic agent Ph790H can be utilized for targeted cancer imaging and fluorescence-guided phototherapy simultaneously. Full article

In the field of drug development, the quest for novel compounds that bind to DNA with high affinity and specificity never ends. In the present work, we report the newest development in this field, namely, triplex DNA-specific binding ligands based on the 5-substituted flavone scaffold in our lab. Biophysical studies showed that the newly synthesized flavone derivatives (depending on the side chains) bind to triplex DNA with binding affinities better than or similar to 5-substituted 3,3′,4′,7-tetramethoxyflavonoids. These compounds selectively stabilize triplex DNA while having little effect on duplex DNA, as verified by various biophysical methods. A detailed structural analysis suggested that the binding of these compounds to triplex DNA depends on the type of amino groups in the side chains and the length of the side chains. Viscosity studies suggested that these ligands bind to triplex DNA via intercalation. A representative ligand, compound 4b, showed a positive inhibitory effect on the activity of a restriction endonuclease (DraI) via ligand-mediated triplex formation. Several of these compounds exhibited excellent cytotoxicity toward various cancer cell lines (HT-29, HCT116, and HL-60), as indicated by the MTT assay. The work presented here is part of a continued effort from our laboratory to explore the novel structural motifs of natural product flavonoids for the development of triplex-specific ligands as antigene enhancers. Full article

The structures of glycans, specifically their terminal positions, play an important role as ligands for receptors in regulating the adhesion ability of platelets. Recent advances in our understanding of free/unbound serotonin (5-HT) in blood plasma at supraphysiological levels implicate it as one of the most profound influencers in remodeling the platelet’s surface N-glycans. Proteomic analysis of the membrane vesicles identified enzymes, specifically glycosyltransferases, only on the surface of the platelets isolated from the supraphysiological level of 5-HT-containing blood plasma. However, these enzymes can only be effective on the cell surface under certain biological conditions, such as the level of their substrates, temperature, and pH of the environment. We hypothesize that exosomes released from various cells coordinate the required criteria for the enzymatic reaction on the platelet surface. The elevated plasma 5-HT level also accelerates the release of exosomes from various cells, as reported. This review summarizes the findings from a wide range of literature and proposes mechanisms to coordinate the exosomes and plasma 5-HT in remodeling the structures of N-glycans to make platelets more prone to aggregation. Full article