There is a current and pressing need for improved cancer therapies. The use of small molecule kin... more There is a current and pressing need for improved cancer therapies. The use of small molecule kinase inhibitors and their application in combinatorial regimens represent an approach to personalized targeted cancer therapy. A number of AGC kinases, including atypical Protein Kinase C enzymes (PKCs), are validated drug targets for cancer treatment. Most drug development programs for protein kinases focus on the development of drugs that bind at the ATP-binding site. Alternatively, allosteric drugs have great potential for the development of future innovative drugs. However, the rational development of allosteric drugs poses important challenges because the compounds not only must bind to a given site but also must stabilize forms of the protein with a desired effect at a distant site. Here we describe the development of a new class of compounds targeting a regulatory site (PIF-pocket) present in the kinase domain and provide biochemical and crystallographic data showing that these compounds allosterically inhibit the activity of atypical PKCs. PS432, a representative compound, decreased the rate of proliferation of non-small cell lung cancer cells more potently than aurothiomalate, an atypical PKCι inhibitor currently under evaluation in clinical trials, and significantly reduced tumor growth without side effects in a mouse xenograft model. The druglike chemical class provides ample possibilities for the synthesis of derivative compounds, with the potential to allosterically modulate the activity of atypical PKCs and other kinases.
Cognitive impairment is a dramatically increasing problem affecting many individuals as well as t... more Cognitive impairment is a dramatically increasing problem affecting many individuals as well as the health system. As we have no causal treatment for the loss of memory, symptomatic treatment is needed. Influencing the ACh system is a generally accepted approach, although other therapeutic treatments are in various stages of development. The multiple target drug approach using hybrid compounds may be another optimized move forward for the treatment of cognitive disorders. Since the complex neuronal regulation is slowly being decoded, there is hope that ways will be found to stop neuronal loss and to generate new synapses.
Histamine H4 Receptor: A Novel Drug Target in Immunoregulation and Inflammation
Since identification and cloning of the histamine H 4 receptor (H 4 R) in 2000 by several groups,... more Since identification and cloning of the histamine H 4 receptor (H 4 R) in 2000 by several groups, the development of H 4 R ligands has been boosted by different drug development programs. The newest member of the histamine receptor family is considered a promising drug target (as described in this book in different chapters). Highly potent and selective H 4 R agonists and antagonists have been published by several groups. The effort to improve the pharmacokinetic properties of the currently available H 4 R ligands is reflected in a steadily growing number of scientific publications and patent applications. Preclinical data strongly confirms the need for novel potent H 4 R ligands to explore their potential therapeutic value in treating allergies, inflammation, autoimmune disorders and, possibly, cancer. The main structural classes of H 4 R ligands are (benz)imidazoles and six-membered nitrogen-containing heterocycles with numerous variations. The objective of this review is to compile currently available H 4 R ligands and to present noticeable structure-activity and structure-selectivity relationships as well as some selected functional and (pre)clinical data.
This study examines the properties of novel guanidines, designed and synthesized as histamine H3R... more This study examines the properties of novel guanidines, designed and synthesized as histamine H3R antagonists/inverse agonists with additional pharmacological targets. We evaluated their potential against two targets viz., inhibition of MDA-MB-231, and MCF-7 breast cancer cells viability and inhibition of AChE/BuChE. ADS10310 showed micromolar cytotoxicity against breast cancer cells, combined with nanomolar affinity at hH3R, and may represent a promising target for the development of an alternative method of cancer therapy. Some of the newly synthesized compounds showed moderate inhibition of BuChE in the single-digit micromolar concentration ranges. H3R antagonist with additional AChE/BuChE inhibitory effect might improve cognitive functions in Alzheimer’s disease. For ADS10310, several in vitro ADME-Tox parameters were evaluated and indicated that it is a metabolically stable compound with weak hepatotoxic activity and can be accepted for further studies.
In an effort to design new hybrid compounds with dual properties, i.e. binding affinity at histam... more In an effort to design new hybrid compounds with dual properties, i.e. binding affinity at histamine H(3) receptors and inhibitory potency at the catabolic enzyme histamine N(tau)-methyltransferase (HMT), a novel series of 1-substituted piperidine derivatives was synthesized. This alicyclic heterocycle is structurally linked via aminoalkyl spacers of variable lengths to additional aromatic carbo- or hetero-cycles. These new hybrid drugs were pharmacologically evaluated regarding their binding affinities at recombinant human H(3) receptors, stably expressed in CHO cells, and in a functional assay for their inhibitory potencies at rat kidney HMT. All compounds investigated proved to be H(3) receptor ligands with binding affinities in the micro- to nanomolar concentration range despite significant differences in the type of the aromatic moiety introduced. The most potent compound in this series was the quinoline derivative 20 (K(i) = 5.6 nM). Likewise, all new ligands studied showed impressive HMT inhibitory activities. Here, compounds 5, 10, 14 and 18-20 exhibited submicromolar potencies (IC(50) = 0.061-0.56 microM). The aminomethylated quinoline 19 showed almost the same, well balanced nanomolar activities on both targets. In this study, new hybrid compounds with a dual mode biological action were developed. These pharmacological agents are valuable leads for further development and candidates for treatment of histamine-dependent disorders.
Pain is a very unpleasant experience that makes life extremely uncomfortable. The histamine H4 re... more Pain is a very unpleasant experience that makes life extremely uncomfortable. The histamine H4 receptor (H4R) is a promising target for the treatment of inflammatory and immune diseases, as well as pain. H4R ligands have demonstrated analgesic effects in a variety of pain models, including inflammatory pain. Continuing the search for active H4R ligands among the alkyl derivatives of 1,3,5-triazine, we obtained 19 new compounds in two series: acyclic (I) and aliphatic (II). In vitro pharmacological evaluation showed their variable affinity for H4R. The majority of compounds showed a moderate affinity for this receptor (Ki > 100 nM), while all compounds tested in ß-arrestin and cAMP assays showed antagonistic activity. The most promising, compound 6, (4-(cyclopentylmethyl)-6-(4-methylpiperazin-1-yl)-1,3,5-triazin-2-amine; Ki = 63 nM) was selected for further in vitro evaluation: blood-brain barrier permeability (PAMPA assay; Pe = 12.26 × 10−6 cm/s) and toxicity tests (HepG2 and SH-...
Long-chain arylpiperazine scaffold is a versatile template to design central nervous system (CNS)... more Long-chain arylpiperazine scaffold is a versatile template to design central nervous system (CNS) drugs that target serotonin and dopamine receptors. Here we describe the synthesis and biological evaluation of ten new arylpiperazine derivatives designed to obtain an affinity profile at serotonin 5-HT1A, 5-HT2A, 5-HT7 receptor, and dopamine D2 receptor of prospective drugs to treat the core symptoms of autism spectrum disorder (ASD) or psychosis. Besides the structural features required for affinity at the target receptors, the new compounds incorporated structural fragments with antioxidant properties to counteract oxidative stress connected with ASD and psychosis. All the new compounds showed CNS MultiParameter Optimization score predictive of desirable ADMET properties and cross the blood–brain barrier. We identified compound 12a that combines an affinity profile compatible with antipsychotic activity (5-HT1AKi = 41.5 nM, 5-HT2AKi = 315 nM, 5-HT7Ki = 42.5 nM, D2Ki = 300 nM), and c...
Two histamine receptor subtypes (HR), namely H1R and H4R, are involved in the transmission of his... more Two histamine receptor subtypes (HR), namely H1R and H4R, are involved in the transmission of histamine-induced itch as key components. Although exact downstream signaling mechanisms are still elusive, transient receptor potential (TRP) ion channels play important roles in the sensation of histaminergic and non-histaminergic itch. The aim of this study was to investigate the involvement of TRPV1 and TRPA1 channels in the transmission of histaminergic itch. The potential of TRPV1 and TRPA1 inhibitors to modulate H1R- and H4R-induced signal transmission was tested in a scratching assay in mice in vivo as well as via Ca2+ imaging of murine sensory dorsal root ganglia (DRG) neurons in vitro. TRPV1 inhibition led to a reduction of H1R- and H4R- induced itch, whereas TRPA1 inhibition reduced H4R- but not H1R-induced itch. TRPV1 and TRPA1 inhibition resulted in a reduced Ca2+ influx into sensory neurons in vitro. In conclusion, these results indicate that both channels, TRPV1 and TRPA1, ar...
Sphingosine 1-phosphate (S1P) is an extensively studied signaling molecule that contributes to ce... more Sphingosine 1-phosphate (S1P) is an extensively studied signaling molecule that contributes to cell proliferation, survival, migration and other functions through binding to specific S1P receptors. The cycle of S1P1 internalization upon S1P binding and recycling to the cell surface when local S1P concentrations are low drives T cell trafficking. S1P1 modulators, such as fingolimod, disrupt this recycling by inducing persistent S1P1 internalization and receptor degradation, which results in blocked egress of T cells from the secondary lymphoid tissues. The approval of these compounds for the treatment of multiple sclerosis has placed the development of S1PR modulators in the focus of pharmacological research, mostly for autoimmune indications. Here, we report on a novel anellated bismorpholino derivative of oxy-fingolimod, named ST-2191, which exerts selective S1P1 agonist and functional antagonist potency. ST-2191 is also effective in reducing the lymphocyte number in mice, and this...
The full-text may be used and/or reproduced, and given to third parties in any format or medium, ... more The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.
A novel class of 5-lipoxygenase (5-LO) inhibitors characterized by a central imidazo[1,2-a]pyridi... more A novel class of 5-lipoxygenase (5-LO) inhibitors characterized by a central imidazo[1,2-a]pyridine scaffold, a cyclohexyl moiety and an aromatic system, is presented. This scaffold was identified in a virtual screening study and exhibits promising inhibitory potential on the 5-LO. Here, we investigate the structure-activity relationships of this compound class. With N-cyclohexyl-6-methyl-2-(4-morpholinophenyl)imidazo[1,2-a]pyridine-3-amine (14), we identified a potent 5-LO inhibitor (IC(50)=0.16μM (intact cells) and 0.1μM (cell-free)), which may possess potential as an effective lead compound intervening with inflammatory diseases and certain types of cancer.
The dissociation behaviours of aripiprazole and cariprazine at the human D and D receptor are eva... more The dissociation behaviours of aripiprazole and cariprazine at the human D and D receptor are evaluated. A potential correlation between kinetics and in vivo profiles, especially cariprazine's action on negative symptoms in schizophrenia, is investigated. The binding kinetics of four ligands were indirectly evaluated. After the receptor preparations were pre-incubated with the unlabelled ligands, the dissociation was initiated with an excess of [H]spiperone. Slow dissociation kinetics characterizes aripiprazole and cariprazine at the D receptor. At the D receptor, aripiprazole exhibits a slow monophasic dissociation, while cariprazine displays a rapid biphasic behaviour. Functional ß-arrestin assays and molecular dynamics simulations at the D receptor confirm a biphasic binding behaviour of cariprazine. This may influence its in vivo action, as the partial agonist could react rapidly to variations in the dopamine levels of schizophrenic patients and the ligand will not quantitat...
Autism spectrum disorder (ASD) is a complex heterogeneous neurodevelopmental disorder characteriz... more Autism spectrum disorder (ASD) is a complex heterogeneous neurodevelopmental disorder characterized by social and communicative impairments, as well as repetitive and restricted behaviors (RRBs). With the limited effectiveness of current pharmacotherapies in treating repetitive behaviors, the present study determined the effects of acute systemic treatment of the novel multi-targeting ligand ST-2223, with incorporated histamine H3 receptor (H3R) and dopamine D2/D3 receptor affinity properties, on ASD-related RRBs in a male Black and Tan BRachyury (BTBR) mouse model of ASD. ST-2223 (2.5, 5, and 10 mg/kg, i.p.) significantly mitigated the increase in marble burying and self-grooming, and improved reduced spontaneous alternation in BTBR mice (all p < 0.05). Similarly, reference drugs memantine (MEM, 5 mg/kg, i.p.) and aripiprazole (ARP, 1 mg/kg, i.p.), reversed abnormally high levels of several RRBs in BTBR (p < 0.05). Moreover, ST-2223 palliated the disturbed anxiety levels obse...
Dopamine is an important neurotransmitter in the human brain and its altered concentrations can l... more Dopamine is an important neurotransmitter in the human brain and its altered concentrations can lead to various neurological diseases. We studied the binding of novel compounds at the dopamine D 2 (D 2 R) and D 3 (D 3 R) receptor subtypes, which belong to the D 2-like receptor family. The synthesis, in silico, and in vitro characterization of 10 dopamine receptor ligands were performed. Novel ligands were docked into the D 2 R and D 3 R crystal structures to examine the precise binding mode. A quantum mechanics/molecular mechanics study was performed to gain insights into the nature of the intermolecular interactions between the newly introduced pentafluorosulfanyl (SF 5) moiety and D 2 R and D 3 R. A radioligand displacement assay determined that all of the ligands showed moderate-to-low nanomolar affinities at D 2 R and D 3 R, with a slight preference for D 3 R, which was confirmed in the in silico studies. N-{4-[4-(2-Methoxyphenyl)piperazin-1-yl]butyl}-4-(pentafluoro-λ6-sulfanyl)benzamide (7i) showed the highest D 3 R affinity and selectivity (pK i values of 7.14 [D 2 R] and 8.42 [D 3 R]).
Neurodegenerative diseases, e.g., Alzheimer’s disease (AD), are a key health problem in the aging... more Neurodegenerative diseases, e.g., Alzheimer’s disease (AD), are a key health problem in the aging population. The lack of effective therapy and diagnostics does not help to improve this situation. It is thought that ligands influencing multiple but interconnected targets can contribute to a desired pharmacological effect in these complex illnesses. Histamine H3 receptors (H3Rs) play an important role in the brain, influencing the release of important neurotransmitters, such as acetylcholine. Compounds blocking their activity can increase the level of these neurotransmitters. Cholinesterases (acetyl- and butyrylcholinesterase) are responsible for the hydrolysis of acetylcholine and inactivation of the neurotransmitter. Increased activity of these enzymes, especially butyrylcholinesterase (BuChE), is observed in neurodegenerative diseases. Currently, cholinesterase inhibitors: donepezil, rivastigmine and galantamine are used in the symptomatic treatment of AD. Thus, compounds simultan...
In an attempt to find new dual acting histamine H3 receptor (H3R) ligands, we designed a series o... more In an attempt to find new dual acting histamine H3 receptor (H3R) ligands, we designed a series of compounds, structurally based on previously described in our group, a highly active and selective human histamine H3 receptor (hH3R) ligand KSK63. As a result, 15 obtained compounds show moderate hH3R affinity, the best being the compound 17 (hH3R Ki = 518 nM). Docking to the histamine H3R homology model revealed two possible binding modes, with key interactions retained in both cases. In an attempt to find possible dual acting ligands, selected compounds were tested for antioxidant properties. Compound 16 (hH3R Ki = 592 nM) showed the strongest antioxidant properties at the concentration of 10−4 mol/L. It significantly reduced the amount of free radicals presenting 50–60% of ascorbic acid activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, as well as showed antioxidative properties in the ferric reducing antioxidant power (FRAP) assay. Despite the yet unknown antioxidation mec...
Alkylglycerol monooxygenase (AGMO) is a tetrahydrobiopterin (BH4)-dependent enzyme with major exp... more Alkylglycerol monooxygenase (AGMO) is a tetrahydrobiopterin (BH4)-dependent enzyme with major expression in the liver and white adipose tissue that cleaves alkyl ether glycerolipids. The present study describes the disclosure and biological characterization of a candidate compound (Cp6), which inhibits AGMO with an IC50 of 30–100 µM and 5–20-fold preference of AGMO relative to other BH4-dependent enzymes, i.e., phenylalanine-hydroxylase and nitric oxide synthase. The viability and metabolic activity of mouse 3T3-L1 fibroblasts, HepG2 human hepatocytes and mouse RAW264.7 macrophages were not affected up to 10-fold of the IC50. However, Cp6 reversibly inhibited the differentiation of 3T3-L1 cells towards adipocytes, in which AGMO expression was upregulated upon differentiation. Cp6 reduced the accumulation of lipid droplets in adipocytes upon differentiation and in HepG2 cells exposed to free fatty acids. Cp6 also inhibited IL-4-driven differentiation of RAW264.7 macrophages towards M...
Human β-defensin 2 (hBD-2) is a potent antimicrobial peptide that participates in defense against... more Human β-defensin 2 (hBD-2) is a potent antimicrobial peptide that participates in defense against invading bacteria. We recently showed that bacterial components and histamine, through histamine H4 receptor (H4R), are involved in the pathogenesis of the potentially malignant lesion, oral lichen planus (OLP). However, the underlying mechanisms remain unknown. We, therefore, investigated the role of hBD2–histamine crosstalk signaling in promoting OLP pathology. Biopsies from OLP and oral tongue squamous cell carcinoma (OTSCC) patients, and healthy controls were used. Two OTSCC cell lines and normal human oral keratinocytes (HOKs) were used. HBD-2 and other targets were mapped by immunostaining and analyzed by ImageJ2 software. The highly sensitive droplet-digital PCR technology and qRT-PCR were utilized to study the clinically derived and in vitro samples, respectively. H4R was challenged with the specific agonist HST-10 and inverse agonist ST-1007. HBD-2 was highly induced in OLP les...
There is a current and pressing need for improved cancer therapies. The use of small molecule kin... more There is a current and pressing need for improved cancer therapies. The use of small molecule kinase inhibitors and their application in combinatorial regimens represent an approach to personalized targeted cancer therapy. A number of AGC kinases, including atypical Protein Kinase C enzymes (PKCs), are validated drug targets for cancer treatment. Most drug development programs for protein kinases focus on the development of drugs that bind at the ATP-binding site. Alternatively, allosteric drugs have great potential for the development of future innovative drugs. However, the rational development of allosteric drugs poses important challenges because the compounds not only must bind to a given site but also must stabilize forms of the protein with a desired effect at a distant site. Here we describe the development of a new class of compounds targeting a regulatory site (PIF-pocket) present in the kinase domain and provide biochemical and crystallographic data showing that these compounds allosterically inhibit the activity of atypical PKCs. PS432, a representative compound, decreased the rate of proliferation of non-small cell lung cancer cells more potently than aurothiomalate, an atypical PKCι inhibitor currently under evaluation in clinical trials, and significantly reduced tumor growth without side effects in a mouse xenograft model. The druglike chemical class provides ample possibilities for the synthesis of derivative compounds, with the potential to allosterically modulate the activity of atypical PKCs and other kinases.
Cognitive impairment is a dramatically increasing problem affecting many individuals as well as t... more Cognitive impairment is a dramatically increasing problem affecting many individuals as well as the health system. As we have no causal treatment for the loss of memory, symptomatic treatment is needed. Influencing the ACh system is a generally accepted approach, although other therapeutic treatments are in various stages of development. The multiple target drug approach using hybrid compounds may be another optimized move forward for the treatment of cognitive disorders. Since the complex neuronal regulation is slowly being decoded, there is hope that ways will be found to stop neuronal loss and to generate new synapses.
Histamine H4 Receptor: A Novel Drug Target in Immunoregulation and Inflammation
Since identification and cloning of the histamine H 4 receptor (H 4 R) in 2000 by several groups,... more Since identification and cloning of the histamine H 4 receptor (H 4 R) in 2000 by several groups, the development of H 4 R ligands has been boosted by different drug development programs. The newest member of the histamine receptor family is considered a promising drug target (as described in this book in different chapters). Highly potent and selective H 4 R agonists and antagonists have been published by several groups. The effort to improve the pharmacokinetic properties of the currently available H 4 R ligands is reflected in a steadily growing number of scientific publications and patent applications. Preclinical data strongly confirms the need for novel potent H 4 R ligands to explore their potential therapeutic value in treating allergies, inflammation, autoimmune disorders and, possibly, cancer. The main structural classes of H 4 R ligands are (benz)imidazoles and six-membered nitrogen-containing heterocycles with numerous variations. The objective of this review is to compile currently available H 4 R ligands and to present noticeable structure-activity and structure-selectivity relationships as well as some selected functional and (pre)clinical data.
This study examines the properties of novel guanidines, designed and synthesized as histamine H3R... more This study examines the properties of novel guanidines, designed and synthesized as histamine H3R antagonists/inverse agonists with additional pharmacological targets. We evaluated their potential against two targets viz., inhibition of MDA-MB-231, and MCF-7 breast cancer cells viability and inhibition of AChE/BuChE. ADS10310 showed micromolar cytotoxicity against breast cancer cells, combined with nanomolar affinity at hH3R, and may represent a promising target for the development of an alternative method of cancer therapy. Some of the newly synthesized compounds showed moderate inhibition of BuChE in the single-digit micromolar concentration ranges. H3R antagonist with additional AChE/BuChE inhibitory effect might improve cognitive functions in Alzheimer’s disease. For ADS10310, several in vitro ADME-Tox parameters were evaluated and indicated that it is a metabolically stable compound with weak hepatotoxic activity and can be accepted for further studies.
In an effort to design new hybrid compounds with dual properties, i.e. binding affinity at histam... more In an effort to design new hybrid compounds with dual properties, i.e. binding affinity at histamine H(3) receptors and inhibitory potency at the catabolic enzyme histamine N(tau)-methyltransferase (HMT), a novel series of 1-substituted piperidine derivatives was synthesized. This alicyclic heterocycle is structurally linked via aminoalkyl spacers of variable lengths to additional aromatic carbo- or hetero-cycles. These new hybrid drugs were pharmacologically evaluated regarding their binding affinities at recombinant human H(3) receptors, stably expressed in CHO cells, and in a functional assay for their inhibitory potencies at rat kidney HMT. All compounds investigated proved to be H(3) receptor ligands with binding affinities in the micro- to nanomolar concentration range despite significant differences in the type of the aromatic moiety introduced. The most potent compound in this series was the quinoline derivative 20 (K(i) = 5.6 nM). Likewise, all new ligands studied showed impressive HMT inhibitory activities. Here, compounds 5, 10, 14 and 18-20 exhibited submicromolar potencies (IC(50) = 0.061-0.56 microM). The aminomethylated quinoline 19 showed almost the same, well balanced nanomolar activities on both targets. In this study, new hybrid compounds with a dual mode biological action were developed. These pharmacological agents are valuable leads for further development and candidates for treatment of histamine-dependent disorders.
Pain is a very unpleasant experience that makes life extremely uncomfortable. The histamine H4 re... more Pain is a very unpleasant experience that makes life extremely uncomfortable. The histamine H4 receptor (H4R) is a promising target for the treatment of inflammatory and immune diseases, as well as pain. H4R ligands have demonstrated analgesic effects in a variety of pain models, including inflammatory pain. Continuing the search for active H4R ligands among the alkyl derivatives of 1,3,5-triazine, we obtained 19 new compounds in two series: acyclic (I) and aliphatic (II). In vitro pharmacological evaluation showed their variable affinity for H4R. The majority of compounds showed a moderate affinity for this receptor (Ki > 100 nM), while all compounds tested in ß-arrestin and cAMP assays showed antagonistic activity. The most promising, compound 6, (4-(cyclopentylmethyl)-6-(4-methylpiperazin-1-yl)-1,3,5-triazin-2-amine; Ki = 63 nM) was selected for further in vitro evaluation: blood-brain barrier permeability (PAMPA assay; Pe = 12.26 × 10−6 cm/s) and toxicity tests (HepG2 and SH-...
Long-chain arylpiperazine scaffold is a versatile template to design central nervous system (CNS)... more Long-chain arylpiperazine scaffold is a versatile template to design central nervous system (CNS) drugs that target serotonin and dopamine receptors. Here we describe the synthesis and biological evaluation of ten new arylpiperazine derivatives designed to obtain an affinity profile at serotonin 5-HT1A, 5-HT2A, 5-HT7 receptor, and dopamine D2 receptor of prospective drugs to treat the core symptoms of autism spectrum disorder (ASD) or psychosis. Besides the structural features required for affinity at the target receptors, the new compounds incorporated structural fragments with antioxidant properties to counteract oxidative stress connected with ASD and psychosis. All the new compounds showed CNS MultiParameter Optimization score predictive of desirable ADMET properties and cross the blood–brain barrier. We identified compound 12a that combines an affinity profile compatible with antipsychotic activity (5-HT1AKi = 41.5 nM, 5-HT2AKi = 315 nM, 5-HT7Ki = 42.5 nM, D2Ki = 300 nM), and c...
Two histamine receptor subtypes (HR), namely H1R and H4R, are involved in the transmission of his... more Two histamine receptor subtypes (HR), namely H1R and H4R, are involved in the transmission of histamine-induced itch as key components. Although exact downstream signaling mechanisms are still elusive, transient receptor potential (TRP) ion channels play important roles in the sensation of histaminergic and non-histaminergic itch. The aim of this study was to investigate the involvement of TRPV1 and TRPA1 channels in the transmission of histaminergic itch. The potential of TRPV1 and TRPA1 inhibitors to modulate H1R- and H4R-induced signal transmission was tested in a scratching assay in mice in vivo as well as via Ca2+ imaging of murine sensory dorsal root ganglia (DRG) neurons in vitro. TRPV1 inhibition led to a reduction of H1R- and H4R- induced itch, whereas TRPA1 inhibition reduced H4R- but not H1R-induced itch. TRPV1 and TRPA1 inhibition resulted in a reduced Ca2+ influx into sensory neurons in vitro. In conclusion, these results indicate that both channels, TRPV1 and TRPA1, ar...
Sphingosine 1-phosphate (S1P) is an extensively studied signaling molecule that contributes to ce... more Sphingosine 1-phosphate (S1P) is an extensively studied signaling molecule that contributes to cell proliferation, survival, migration and other functions through binding to specific S1P receptors. The cycle of S1P1 internalization upon S1P binding and recycling to the cell surface when local S1P concentrations are low drives T cell trafficking. S1P1 modulators, such as fingolimod, disrupt this recycling by inducing persistent S1P1 internalization and receptor degradation, which results in blocked egress of T cells from the secondary lymphoid tissues. The approval of these compounds for the treatment of multiple sclerosis has placed the development of S1PR modulators in the focus of pharmacological research, mostly for autoimmune indications. Here, we report on a novel anellated bismorpholino derivative of oxy-fingolimod, named ST-2191, which exerts selective S1P1 agonist and functional antagonist potency. ST-2191 is also effective in reducing the lymphocyte number in mice, and this...
The full-text may be used and/or reproduced, and given to third parties in any format or medium, ... more The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.
A novel class of 5-lipoxygenase (5-LO) inhibitors characterized by a central imidazo[1,2-a]pyridi... more A novel class of 5-lipoxygenase (5-LO) inhibitors characterized by a central imidazo[1,2-a]pyridine scaffold, a cyclohexyl moiety and an aromatic system, is presented. This scaffold was identified in a virtual screening study and exhibits promising inhibitory potential on the 5-LO. Here, we investigate the structure-activity relationships of this compound class. With N-cyclohexyl-6-methyl-2-(4-morpholinophenyl)imidazo[1,2-a]pyridine-3-amine (14), we identified a potent 5-LO inhibitor (IC(50)=0.16μM (intact cells) and 0.1μM (cell-free)), which may possess potential as an effective lead compound intervening with inflammatory diseases and certain types of cancer.
The dissociation behaviours of aripiprazole and cariprazine at the human D and D receptor are eva... more The dissociation behaviours of aripiprazole and cariprazine at the human D and D receptor are evaluated. A potential correlation between kinetics and in vivo profiles, especially cariprazine's action on negative symptoms in schizophrenia, is investigated. The binding kinetics of four ligands were indirectly evaluated. After the receptor preparations were pre-incubated with the unlabelled ligands, the dissociation was initiated with an excess of [H]spiperone. Slow dissociation kinetics characterizes aripiprazole and cariprazine at the D receptor. At the D receptor, aripiprazole exhibits a slow monophasic dissociation, while cariprazine displays a rapid biphasic behaviour. Functional ß-arrestin assays and molecular dynamics simulations at the D receptor confirm a biphasic binding behaviour of cariprazine. This may influence its in vivo action, as the partial agonist could react rapidly to variations in the dopamine levels of schizophrenic patients and the ligand will not quantitat...
Autism spectrum disorder (ASD) is a complex heterogeneous neurodevelopmental disorder characteriz... more Autism spectrum disorder (ASD) is a complex heterogeneous neurodevelopmental disorder characterized by social and communicative impairments, as well as repetitive and restricted behaviors (RRBs). With the limited effectiveness of current pharmacotherapies in treating repetitive behaviors, the present study determined the effects of acute systemic treatment of the novel multi-targeting ligand ST-2223, with incorporated histamine H3 receptor (H3R) and dopamine D2/D3 receptor affinity properties, on ASD-related RRBs in a male Black and Tan BRachyury (BTBR) mouse model of ASD. ST-2223 (2.5, 5, and 10 mg/kg, i.p.) significantly mitigated the increase in marble burying and self-grooming, and improved reduced spontaneous alternation in BTBR mice (all p < 0.05). Similarly, reference drugs memantine (MEM, 5 mg/kg, i.p.) and aripiprazole (ARP, 1 mg/kg, i.p.), reversed abnormally high levels of several RRBs in BTBR (p < 0.05). Moreover, ST-2223 palliated the disturbed anxiety levels obse...
Dopamine is an important neurotransmitter in the human brain and its altered concentrations can l... more Dopamine is an important neurotransmitter in the human brain and its altered concentrations can lead to various neurological diseases. We studied the binding of novel compounds at the dopamine D 2 (D 2 R) and D 3 (D 3 R) receptor subtypes, which belong to the D 2-like receptor family. The synthesis, in silico, and in vitro characterization of 10 dopamine receptor ligands were performed. Novel ligands were docked into the D 2 R and D 3 R crystal structures to examine the precise binding mode. A quantum mechanics/molecular mechanics study was performed to gain insights into the nature of the intermolecular interactions between the newly introduced pentafluorosulfanyl (SF 5) moiety and D 2 R and D 3 R. A radioligand displacement assay determined that all of the ligands showed moderate-to-low nanomolar affinities at D 2 R and D 3 R, with a slight preference for D 3 R, which was confirmed in the in silico studies. N-{4-[4-(2-Methoxyphenyl)piperazin-1-yl]butyl}-4-(pentafluoro-λ6-sulfanyl)benzamide (7i) showed the highest D 3 R affinity and selectivity (pK i values of 7.14 [D 2 R] and 8.42 [D 3 R]).
Neurodegenerative diseases, e.g., Alzheimer’s disease (AD), are a key health problem in the aging... more Neurodegenerative diseases, e.g., Alzheimer’s disease (AD), are a key health problem in the aging population. The lack of effective therapy and diagnostics does not help to improve this situation. It is thought that ligands influencing multiple but interconnected targets can contribute to a desired pharmacological effect in these complex illnesses. Histamine H3 receptors (H3Rs) play an important role in the brain, influencing the release of important neurotransmitters, such as acetylcholine. Compounds blocking their activity can increase the level of these neurotransmitters. Cholinesterases (acetyl- and butyrylcholinesterase) are responsible for the hydrolysis of acetylcholine and inactivation of the neurotransmitter. Increased activity of these enzymes, especially butyrylcholinesterase (BuChE), is observed in neurodegenerative diseases. Currently, cholinesterase inhibitors: donepezil, rivastigmine and galantamine are used in the symptomatic treatment of AD. Thus, compounds simultan...
In an attempt to find new dual acting histamine H3 receptor (H3R) ligands, we designed a series o... more In an attempt to find new dual acting histamine H3 receptor (H3R) ligands, we designed a series of compounds, structurally based on previously described in our group, a highly active and selective human histamine H3 receptor (hH3R) ligand KSK63. As a result, 15 obtained compounds show moderate hH3R affinity, the best being the compound 17 (hH3R Ki = 518 nM). Docking to the histamine H3R homology model revealed two possible binding modes, with key interactions retained in both cases. In an attempt to find possible dual acting ligands, selected compounds were tested for antioxidant properties. Compound 16 (hH3R Ki = 592 nM) showed the strongest antioxidant properties at the concentration of 10−4 mol/L. It significantly reduced the amount of free radicals presenting 50–60% of ascorbic acid activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, as well as showed antioxidative properties in the ferric reducing antioxidant power (FRAP) assay. Despite the yet unknown antioxidation mec...
Alkylglycerol monooxygenase (AGMO) is a tetrahydrobiopterin (BH4)-dependent enzyme with major exp... more Alkylglycerol monooxygenase (AGMO) is a tetrahydrobiopterin (BH4)-dependent enzyme with major expression in the liver and white adipose tissue that cleaves alkyl ether glycerolipids. The present study describes the disclosure and biological characterization of a candidate compound (Cp6), which inhibits AGMO with an IC50 of 30–100 µM and 5–20-fold preference of AGMO relative to other BH4-dependent enzymes, i.e., phenylalanine-hydroxylase and nitric oxide synthase. The viability and metabolic activity of mouse 3T3-L1 fibroblasts, HepG2 human hepatocytes and mouse RAW264.7 macrophages were not affected up to 10-fold of the IC50. However, Cp6 reversibly inhibited the differentiation of 3T3-L1 cells towards adipocytes, in which AGMO expression was upregulated upon differentiation. Cp6 reduced the accumulation of lipid droplets in adipocytes upon differentiation and in HepG2 cells exposed to free fatty acids. Cp6 also inhibited IL-4-driven differentiation of RAW264.7 macrophages towards M...
Human β-defensin 2 (hBD-2) is a potent antimicrobial peptide that participates in defense against... more Human β-defensin 2 (hBD-2) is a potent antimicrobial peptide that participates in defense against invading bacteria. We recently showed that bacterial components and histamine, through histamine H4 receptor (H4R), are involved in the pathogenesis of the potentially malignant lesion, oral lichen planus (OLP). However, the underlying mechanisms remain unknown. We, therefore, investigated the role of hBD2–histamine crosstalk signaling in promoting OLP pathology. Biopsies from OLP and oral tongue squamous cell carcinoma (OTSCC) patients, and healthy controls were used. Two OTSCC cell lines and normal human oral keratinocytes (HOKs) were used. HBD-2 and other targets were mapped by immunostaining and analyzed by ImageJ2 software. The highly sensitive droplet-digital PCR technology and qRT-PCR were utilized to study the clinically derived and in vitro samples, respectively. H4R was challenged with the specific agonist HST-10 and inverse agonist ST-1007. HBD-2 was highly induced in OLP les...
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Papers by Holger Stark