Receptor Synthesis Research Articles

Lower‐Rim‐Modified Calix[4]arene‐Pyrrolotetrathiafulvalene Molecular Tweezers

AbstractAn approach for the lower rim modification of the calix[4]arene‐based molecular tweezes with monopyrrolo‐tetrathiafulvalene (MPTTF) arms attached to the upper rim of calixarenes is described. First, calixarene‐MPTTF conjugates with free hydroxyl on the lower rim are synthesized using the Ullmann reaction, then hydroxyl groups are substituted by propargyl groups, which can be used for further modification by the click reaction. The new calixarene‐TTF derivatives displayed reversible redox processes, as well as demonstrated binding affinity for electron‐deficient molecular guests such as tetracyanoquinodimethane. The described synthetic approach will be used for the modular synthesis of molecular receptors tailored for specific applications.

Kinesin Nanomotors Mediated Trafficking of NMDA-Loaded Cargo as A Novel Target in Chronic Pain.

Chronic pain is among the most prevalent burdensome disorders worldwide. The N-methyl-d-aspartate (NMDA) receptor system plays a critical role in central sensitization, a primary feature of chronic pain. Despite the proven efficacy of exogenous ligands to this receptor system in preclinical studies, evidence for the clinical efficacy of NMDA antagonists for the treatment of chronic pain is weak. Researchers are studying alternate approaches, rather than direct inhibition of the NMDA receptors in pain processing neurons. This indirect approach utilizes the modulation of molecular switches that regulates the synthesis, maturation, and transport of receptors from cellular organelles to the synaptic membrane. Kinesins are nanomotors that anterogradely transport the cargo using microtubule tracks across the neurons. Various members of the kinesin family, including KIF17, KIF11, KIF5b, and KIF21a, regulate the intracellular transport of NMDA receptors. Pharmacological targeting of these ATP-driven nanomotors could be a useful tool for manipulating the NMDAR functioning. It could provide the potential for the development of a novel strategy for the management of chronic pain.

A Disposable Saliva Electrochemical MIP-Based Biosensor for Detection of the Stress Biomarker α-Amylase in Point-of-Care Applications

The design and synthesis of artificial receptors based on molecular imprinting (MI) technology for the development of a new MIP-based biosensor for detection of the stress biomarker α-amylase in human saliva in point-of-care (PoC) applications is described in this work. The portable electrochemical devices for monitoring α-amylase consists of cost-effective and disposable gold screen-printed electrodes (AuSPEs). To build the electrochemical device, the template biomolecule was firstly immobilized directly over the working area of the gold chip previously activated with a self-assembled monolayer (SAM) of cysteamine (CA). Then, pyrrole (Py) monomer was selected as building block of a polymeric network prepared by CV electropolymerization. After the electropolymerization process, the enzyme was removed from the polymer film in order to build the specific recognition sites for the target enzyme. The MIP biosensor showed a very wide linear concentration range (between 3.0 × 10−4 to 0.60 mg mL−1 in buffer solution and between 3.0 × 10−4 to 3.0 × 10−2 mg mL−1 in human saliva) and low detection levels were achieved (LOD < 3.0 × 10−4 mg mL−1) using square wave voltammetry (SWV) as the electroanalytical technique.

A Vibration-Induced-Emission-Based Fluorescent Chemosensor for the Selective and Visual Recognition of Glucose.

The development of chemosensors to detect analytes in biologically relevant solutions is a challenging task. We report the synthesis of a fluorescent receptor that combines vibration‐induced emission (VIE) and dynamic covalent chemistry for the detection of glucose in aqueous media. We show that the bis‐2‐(N‐methylaminomethyl)phenylboronic acid‐decorated N,N′‐diphenyl‐dihydrodibenzo[a,c]phenazine (DPAC) receptor 1 can detect glucose and discriminate between closely related monosaccharides including those commonly found in blood. Preliminary studies suggest monosaccharides bind to the DPAC‐receptor with a 1:1 stoichiometry to produce pseudomacrocyclic complexes, which in turn leads to distinct optical changes in the fluorescent emission of the receptor for each host. Moreover, the complexation‐induced change in emission can be detected visually and quantified in a ratiometric way. Our results highlight the potential of VIE‐type receptors for the quantitative determination of saccharides in biological samples.

A Vibration‐Induced‐Emission‐Based Fluorescent Chemosensor for the Selective and Visual Recognition of Glucose

AbstractThe development of chemosensors to detect analytes in biologically relevant solutions is a challenging task. We report the synthesis of a fluorescent receptor that combines vibration‐induced emission (VIE) and dynamic covalent chemistry for the detection of glucose in aqueous media. We show that the bis‐2‐(N‐methylaminomethyl)phenylboronic acid‐decorated N,N′‐diphenyl‐dihydrodibenzo[a,c]phenazine (DPAC) receptor 1 can detect glucose and discriminate between closely related monosaccharides including those commonly found in blood. Preliminary studies suggest monosaccharides bind to the DPAC‐receptor with a 1:1 stoichiometry to produce pseudomacrocyclic complexes, which in turn leads to distinct optical changes in the fluorescent emission of the receptor for each host. Moreover, the complexation‐induced change in emission can be detected visually and quantified in a ratiometric way. Our results highlight the potential of VIE‐type receptors for the quantitative determination of saccharides in biological samples.

CMAS and ST3GAL4 Play an Important Role in the Adsorption of Influenza Virus by Affecting the Synthesis of Sialic Acid Receptors.

Influenza A viruses (IAVs) initiate infection by attaching Hemagglutinin (HA) on the viral envelope to sialic acid (SA) receptors on the cell surface. Importantly, HA of human IAVs has a higher affinity for α-2,6-linked SA receptors, and avian strains prefer α-2,3-linked SA receptors, whereas swine strains have a strong affinity for both SA receptors. Host gene CMAS and ST3GAL4 were found to be essential for IAV attachment and entry. Loss of CMAS and ST3GAL4 hindered the synthesis of sialic acid receptors, which in turn prevented the adsorption of IAV. Further, the knockout of CMAS had an effect on the adsorption of swine, avian and human IAVs. However, ST3GAL4 knockout prevented the adsorption of swine and avian IAV and the impact on avian IAV was more distinct, whereas it had no effect on the adsorption of human IAV. Collectively, our findings demonstrate that knocking out CMAS and ST3GAL4 negatively regulated IAV replication by inhibiting the synthesis of SA receptors, which also provides new insights into the production of gene-edited animals in the future.

Design and Electrochemical Investigation of Ureido-Sulfonamidic Receptors for Phosphates

Anions play an important role in biological systems. At the same time, many of them are the major environmental pollutants and substances endangering living organisms [1]. For these purposes the anion recognition, elimination and sensing would find application in many branches including application in medicine or environmental chemistry. Suitable examples of anion pollutants are phosphates, which could cause eutrophication of water and they are also known for their limited removal from body fluids, which could lead to serious health problems. Therefore, the aim of our research group is the design and preparation of anionic receptors with suitable binding sites to bind these anions.In the first step of our synthesis a series of substituted nosylamidic intermediates (fig. a, b) was prepared. These substances are suitable precursors for the synthesis of novel receptors bearing ureido functions (fig. c). The sulfonamidic motif itself is known as a neutral donor of hydrogen bond. Hence for better understanding of the behaviour of the final urea receptors, the properties of intermediate molecules were studied by various physicochemical techniques including spectroscopic and electrochemical methods.Spectroscopic methods were used to evaluate the binding ability of this motif and to determine its acid-basic properties. Electrochemical methods (represented by polarography and cyclic voltammetry with mercury dropping or hanging electrodes in dimethylformamide with Bu4N PF6 as electrolyte) were chosen because the nitro groups in our intermediate molecules are not only important substituents enabling continuation in synthesis, but also electrochemical "probes" reflecting the properties of the parent molecule. Their reduction in aprotic media is generally known after the first one-electron reversible reduction step where a stable radical anion is formed, a three-electron irreversible process follows resulting in the corresponding hydroxylamine [2]. However, the reduction pattern of the series (b) is totally different: After the first irreversible step (theoretically involving 4/5 of electron) a one-electron reversible reduction takes place followed by a multielectron process. This behaviour can be explained by using autoprotonation mechanism [3] where the acidic hydrogen of the sulfonamidic group is involved.Then our attention focused on final receptors (fig c). It was shown, that sulfonamidic moiety can be utilized as an electron-withdrawing group useful to enhance the anion complexation properties of urea-based receptors. On the other hand, it brings an inherent predisposition for deprotonation in the presence of more basic anions. In order to shift the deprotonation/complexation equilibrium in favour of the complexation, the receptors were derivatized by electron-donating groups like –OCH3 at sulfonamidic moiety. The binding for this receptor was evaluated in a competitive solvent (DMSO) by using NMR titration experiments. The experimental results show a considerable selectivity of our receptor to phosphates compared to another biologically important anions such as Cl-, NO3 - and HSO4 - [4].Based on these results, the prepared receptors appear to be suitable motifs for binding phosphate anions. In order to take advantage of their binding capabilities, these molecules need to be attached to the surface of a suitable molecular carrier. The formation of these functional materials (in our case especially dendrimers) is also associated with the need to design and optimize methods to describe anion binding ability, as well as the possibility to recycle the prepared materials. This was the reason for which it seems to be interesting to consider the presence of an electrochemical “probe” also in the final molecular receptors. The redox transformation of such a probe should fundamentally affect the complexing abilities of the receptor and allow targeted degradation of the complex. Acknowledgements: The work was supported by the grant number 18-12150S and 20-07833S.

Clinical manifestations of familial hypercholesterolemia: a case series

Familial hypercholesterolemia is a rare, monogenic, co-dominant, life-threatening disorder resulting from loss of function mutations in the genes responsible for synthesis of low-density lipoprotein receptors or apo-B genes or gain of function mutations in PCSK9 genes in the liver which affects 0.2% of the population. It is characterized by severe lifelong elevation of LDL cholesterol and by development of xanthelasma, xanthomas, premature coronary artery disease and peripheral artery occlusive disease. Most patients develop PCAD and aortic stenosis before the age of 20 years and die before 30 years of age. The diagnosis of FH is usually based on clinical presentation and commonly used criteria are the Dutch lipid clinic network criteria, Simon Broome criteria or the WHO criteria. We encountered four cases of familial hypercholesterolemia over last 10 years. All the four patients presented with effort angina and all were found to have obstructive coronary artery disease oncoronary angiogram and two of them had severe supravalvular aortic stenosis. All four patients were on dietary modifications, high intensity statin and cholesterol absorption inhibitor. Two patients underwent coronary artery bypass grafting with aortoplasty, one patient underwent coronary artery bypass grafting and one patient underwent percutaneous transluminal coronary angioplasty. Familial hypercholesterolemia leads to development of life-threatening manifestations early in the second and third decades of life. Early diagnosis, aggressive treatment and control of risk factors and cascade screening are important in management and will help to reduce the morbidity and mortality associated with this disease.

Invitro effect of pine bark extract on melanin synthesis, tyrosinase activity, production of endothelin-1, and PPAR in cultured melanocytes exposed to Ultraviolet, Infrared, and Visible light radiation.

French maritime pine bark (Pinus pinaster) extract (PBE), the registered trade name of which is Pycnogenol® , has been studied for its depigmenting action due to its antioxidant, anti-inflammatory, and anti-melanogenic activity. However, the mechanisms through which PBE are still not fully clear. Evaluate the impact of PBE on four in vitro parameters closely associated with cutaneous pigmentation, including melanin synthesis, tyrosinase activity, endothelin-1 (ED1), and production of peroxisome proliferator-activated receptor α, δ, and γ (PPAR α, δ, and γ), by studying the modulation of action of ultraviolet radiation A (UVA)/ultraviolet radiation B (UVB), infrared-A (IR-A), visible light (VL), and association of UVA/UVB, IR-A, and VL (ASS). Human melanocytes were incubated in a dry extract solution of PBE, exposed to UVA/UVB, IR-A, VL, and ASS for subsequent quantification of melanin, ED1, and PPAR α, δ, and γ. The effects of PBE on inhibition of tyrosinase activity were also performed by monophenolase activity assay. UVA/UVB, IR-A, VL, and ASS radiation caused significant increases in the synthesis of melanin, ED1, and PPAR α, δ, and γ when compared to baseline control. However, PBE significantly reduced the production of melanin, ED1, and PPAR α, δ, and γ, as well as reducing about 66.5% of the tyrosinase activity. PBE reduces in vitro melanin production by downregulating tyrosinase and reducing pigmentation-related mediators, such as ED1 and PPAR α, δ, and γ, therefore contributing to the inhibition of pathways associated with skin hyperpigmentation.

SP-007 - Synthesis, radiolabeling and biological evaluation of a novel trace amine-associated receptor 1 (TAAR1) PET radioligand

SP-007 - Synthesis, radiolabeling and biological evaluation of a novel trace amine-associated receptor 1 (TAAR1) PET radioligand

Design, synthesis, and biological evaluation of a novel dual peroxisome proliferator-activated receptor alpha/delta agonist for the treatment of diabetic kidney disease through anti-inflammatory mechanisms.

Diabetic kidney disease (DKD) is a major feature of the final stage of nearly all cause types of diabetes mellitus (DM). To date, few safe and effective drugs are available to treat. Peroxisome proliferator-activated receptors (PPARs), comprised of three members: PPAR-α, PPAR-δ and PPAR-γ, play a protective role in the DKD through glycemic control and lipid metabolism, whereas systemic activation of PPAR-γ causes serious side-effects in clinical trials. GFT505 is a dual PPAR-α/δ agonist, and the selectivity against PPAR-γ is still to be improved. Sulfuretin has been shown to suppress the expression of PPAR-γ and improve the pathogenesis of diabetic complications. In this study, by hybridizing the carboxylic acid of GFT505 and the parent nucleus of sulfuretin, we pioneeringly designed and synthetized a series of novel dual PPAR-α/δ agonists, expecting to provide a better benefit/risk ratio for PPARs. Of all the synthesized compounds, compound 12 was identified with highly activity on PPAR-α/δ and higher selectivity against PPAR-γ than that of GFT505 (EC50: hPPAR-α: 0.26μM vs.0.76μM; hPPAR-δ: 0.50μM vs.0.73μM; hPPAR-γ: 4.22μM vs.2.79μM). The molecular docking studies also depicted good binding affinity of compound 12 for PPAR-α and PPAR-δ compared to GFT505. Furthermore, compound 12 exhibited an evidently renoprotective effect on the DKD through inhibiting inflammatory process, which might at least partly via JNK/NF-κB pathways invivo and invitro. Overall, compound 12 hold therapeutic promise for DKD.

Transcriptomic analysis reveals the molecular mechanisms of rumen wall morphological and functional development induced by different solid diet introduction in a lamb model

BackgroundThis study aimed to elucidate the molecular mechanisms of solid diet introduction initiating the cellular growth and maturation of rumen tissues and characterize the shared and unique biological processes upon different solid diet regimes.MethodsTwenty-four Hu lambs were randomly allocated to three groups fed following diets: goat milk powder only (M, n = 8), goat milk powder + alfalfa hay (MH, n = 8), and goat milk powder + concentrate starter (MC, n = 8). At 42 days of age, the lambs were slaughtered. Ruminal fluid sample was collected for analysis of concentration of volatile fatty acid (VFA) and microbial crude protein (MCP). The sample of the rumen wall from the ventral sac was collected for analysis of rumen papilla morphology and transcriptomics.ResultsCompared with the M group, MH and MC group had a higher concentration of VFA, MCP, rumen weight, and rumen papilla area. The transcriptomic results of rumen wall showed that there were 312 shared differentially expressed genes (DEGs) between in “MH vs. M” and “MC vs. M”, and 232 or 796 unique DEGs observed in “MH vs. M” or “MC vs. M”, respectively. The shared DEGs were most enriched in VFA absorption and metabolism, such as peroxisome proliferator-activated receptor (PPAR) signaling pathway, butanoate metabolism, and synthesis and degradation of ketone bodies. Additionally, a weighted gene co-expression network analysis identified M16 (2,052 genes) and M18 (579 genes) modules were positively correlated with VFA and rumen wall morphology. The M16 module was mainly related to metabolism pathway, while the M18 module was mainly associated with signaling transport. Moreover, hay specifically depressed expression of genes involved in cytokine production, immune response, and immunocyte activation, and concentrate starter mainly altered nutrient transport and metabolism, especially ion transport, amino acid, and fatty acid metabolism.ConclusionsThe energy production during VFA metabolism may drive the rumen wall development directly. The hay introduction facilitated establishment of immune function, while the concentrate starter enhanced nutrient transport and metabolism, which are important biological processes required for rumen development.

Structure based design and synthesis of novel Toll-like Receptor 2 (TLR 2) lipid antagonists

Toll-like receptors (TLRs) play key role in innate immune response to Damage Associated Molecular Patterns (DAMPs) and Pathogen Associated Molecular Patterns (PAMPs). DAMP/PAMP-mediated activation of TLRs triggers NFκB signaling resulting in pro-inflammatory cytokine release. Using TLR2-Pam2CSK4 agonist co-crystal structure information, we designed and synthesized a novel series of Toll-like Receptor 2 (TLR2) lipid antagonists and identified compounds 14, 15 and 17 with sub-micromolar potency. TLR2 antagonists that we identified are stable for > 1.0 h in both gastric juice and PBS buffer and could be used as research tools.

Comparing the anion binding of 4-amido- with 4-amino-1,8-naphthalimides

The synthesis and evaluation of a new anion receptor based on the 4-amido-1,8-naphthalimide scaffold is described. The findings indicate that the amide N-H is an enhanced H-bond donor but is otherwise restricted in its ability to participate in the binding of simple anions.

Superphane: a new lantern-like receptor for encapsulation of a water dimer.

A new superphane, featuring an aesthetically pleasing structure, was successfully obtained via one-pot synthesis of a hexakis-amine and m-phthalaldehyde in a [2+6] manner. It proved capable of entrapping a water dimer within its cavity as inferred from the mass spectroscopy, crystallographical analysis, NMR spectroscopy, and theoretical calculations.

Bile acids, non-alcoholic fatty liver and pancreatic disease: chained by ursodeoxycholic acid?

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic fatty pancreatic disease (NAFPD) develop against the background of metabolic syndrome, systemic insulin resistance, oxidative stress, changes in lipid and carbohydrate metabolism. There are a number of similarities between NAFLD and NAFPD: the natural course of diseases proceeds from steatosis through inflammation to fibrosis and cancer, one of the etiopathogenetic factors is the disbalance of bile acids synthesis and low expression of farnesoid receptor X (FXR). One of the possible methods of treatment NAFLD and NAFPD is a correction of the biosynthesis of bile acids and increase FXR expression with FXR agonists. Ursodeoxycholic acid (UDCA) is a selective FXR agonist. It has a multipled spectrum of actions: anticholestatic, anti-apoptic, antioxidant, cytoprotective, antifibrotic, hypocholesterolemic, immunomodulatory, hepatoprotective. The ability of UDCA correct lipid and carbohydrate metabolism in combination with anti-inflammatory and antiapoptic effects may be of great importance for the treatment of NAFLD and NAFPD. The article reviews the results of clinical and experimental studies describing the efficacy of UDCA in NAFLD and some pancreatic diseases. It has been suggested that the therapy of UDCA can reduce the severity of NAFLD and NAFPDand improve the functional activity of hepatocytes and β cells. The need for randomized clinical trials was emphasized in order to make an informed decision on the expediency of including UDCA in the treatment of NAFLD and NAFPD.

Loss of apyoverdine secondary receptor in Pseudomonas aeruginosa results in a fitter strain suitable for population invasion.

The rapid emergence of antibiotic resistant bacterial pathogens constitutes a critical problem in healthcare and requires the development of novel treatments. Potential strategies include the exploitation of microbial social interactions based on public goods, which are produced at a fitness cost by cooperative microorganisms, but can be exploited by cheaters that do not produce these goods. Cheater invasion has been proposed as a 'Trojan horse' approach to infiltrate pathogen populations with strains deploying built-in weaknesses (e.g., sensitiveness to antibiotics). However, previous attempts have been often unsuccessful because population invasion by cheaters was prevented by various mechanisms including the presence of spatial structure (e.g., growth in biofilms), which limits the diffusion and exploitation of public goods. Here we followed an alternative approach and examined whether the manipulation of public good uptake and not its production could result in potential 'Trojan horses' suitable for population invasion. We focused on the siderophore pyoverdine produced by the human pathogen Pseudomonas aeruginosa MPAO1 and manipulated its uptake by deleting and/or overexpressing the pyoverdine primary (FpvA) and secondary (FpvB) receptors. We found that receptor synthesis feeds back on pyoverdine production and uptake rates, which led to strains with altered pyoverdine-associated costs and benefits. Moreover, we found that the receptor FpvB was advantageous under iron-limited conditions but revealed hidden costs in the presence of an antibiotic stressor (gentamicin). As a consequence, FpvB mutants became the fittest strain under gentamicin exposure, displacing the wildtype in liquid cultures, and in biofilms and during infections of the wax moth larvae Galleria mellonella, which both represent structured environments. Our findings reveal that an evolutionary trade-off associated with the costs and benefits of a versatile pyoverdine uptake strategy can be harnessed for devising a Trojan-horse candidate for medical interventions.

Donor variation and sex hormone receptors in periodontal ligament cells

ObjectiveThis study evaluated the gene expression and protein synthesis of sex hormone receptors in human periodontal ligament cells (PDLCs) in relation to donor- and tooth-specific factors with the aim to clarify the debate about sex hormone receptors in PDLCs. DesignThe expression patterns of estrogen receptors (genes: ESR1 and ESR2; proteins: ERα and ERβ), androgen receptor (AR) and progesterone receptor (PR) were investigated in the context of immortalization status, previous orthodontic tooth movement (OTM), donor age, sex and hormonal stimulation in PDLCs from 14 healthy donors (male: n = 8, female: n = 6; adolescents: n = 8, adults: n = 6) using quantitative real-time polymerase chain reaction, Western blot and immunocytochemistry. ResultsFor ERβ, the full-length isoform ERβ1 and truncated variants were detected. For ERα, the expected isoform ERα66 was not observed, but a novel isoform ERα36 was detected. Immortalization status, previous OTM and donor age had no impact on ESR1 and ESR2 expression. Estradiol stimulation for 24 h doubled the ratio of ESR2/ESR1 in PDLCs from female but not male donors, indicating sex-specific patterns of receptor expression. AR and PR demonstrated insufficient protein synthesis in PDLCs. ConclusionsThe data revealed a pivotal role for and complex interplay between ERα and ERβ in human PDLCs regardless of variable donor characteristics. Therefore, PDLC biology might be altered in patients of each age group and both sexes due to hormonal changes. This should be kept in mind during periodontic and orthodontic treatment of patients with special hormonal status.

Evidence that EZH2 Deregulation is an Actionable Therapeutic Target for Prevention of Prostate Cancer

Chemoprevention trials for prostate cancer by androgen receptor or androgen synthesis inhibition have proven ineffective. Recently, it has been demonstrated that the histone methlytransferase, EZH2 is deregulated in mouse and human high-grade prostatic intraepithelial neoplasia (HG-PIN). Using preclinical mouse and human models of prostate cancer, we demonstrate that genetic and chemical disruption of EZH2 expression and catalytic activity reversed the HG-PIN phenotype. Furthermore, inhibition of EZH2 function was associated with loss of cellular proliferation and induction of Tp53-dependent senescence. Together, these data provide provocative evidence for EZH2 as an actionable therapeutic target toward prevention of prostate cancer.

Design, synthesis and evaluation of a tripodal receptor for phosphatidylinositol phosphates

Phosphatidylinositol phosphates (PIPs) are membrane phospholipids that play crucial roles in a wide range of cellular processes. Their function is dictated by the number and positions of the phosphate groups in the inositol ring (with seven different PIPs being active in the cell). Therefore, there is significant interest in developing small-molecule receptors that can bind selectively to these species and in doing so affect their cellular function or be the basis for molecular probes. However, to date there are very few examples of such molecular receptors. Towards this aim, herein we report a novel tripodal molecule that acts as receptor for mono- and bis-phosphorylated PIPs in a cell free environment. To assess their affinity to PIPs we have developed a new cell free assay based on the ability of the receptor to prevent alkaline phosphatase from hydrolysing these substrates. The new receptor displays selectivity towards two out of the seven PIPs, namely PI(3)P and PI(3,4)P2. To rationalise these results, a DFT computational study was performed which corroborated the experimental results and provided insight into the host–guest binding mode.