Affinity For 5-HT1A Receptors Research Articles

Procognitive, Anxiolytic, and Antidepressant-like Properties of Hyperoside and Protocatechuic Acid Corresponding with the Increase in Serum Serotonin Level after Prolonged Treatment in Mice.

Two polyphenols-hyperoside (HYP) and protocatechuic acid (PCA) were reported to exert antidepressant activity in rodents after acute treatment. Our previous study also showed that this activity might have been influenced by the monoaminergic system and the upregulation of the brain-derived neurotropic factor (BDNF) level. A very long-term pharmacological therapy is required for the treatment of a patient with depression. The repetitive use of antidepressants is recognized to impact the brain structures responsible for regulating both emotional and cognitive behaviors. Thus, we investigated the antidepressant, anxiolytic, and procognitive effects of HYP and PCA in mice after acute and prolonged treatment (14 days). Both polyphenols induced an anxiogenic-like effect after acute treatment, whereas an anxiolytic effect occurred after repetitive administration. PCA and HYP showed procognitive effects when they were administered acutely and chronically, but it seems that their influence on long-term memory was stronger than on short-term memory. In addition, the preset study showed that the dose of 7.5 mg/kg of PCA and HYP was effective in counteracting the effects of co-administered scopolamine in the long-term memory impairment model induced by scopolamine. Our experiments revealed the compounds have no affinity for 5-HT1A and 5-HT2A receptors, whereas a significant increase in serum serotonin level after prolonged administration of PCA and HYP at a dose of 3.75 mg/kg was observed. Thus, it supports the involvement of the serotonergic system in the polyphenol mechanisms. These findings led us to hypothesize that the polyphenols isolated from Impatiens glandulifera can hold promise in treating mental disorders with cognitive dysfunction. Consequently, extended studies are necessary to delve into their pharmacological profile.

Synthesis and biological evaluation of novel 3-(5-substituted-1H-indol-3-yl)pyrrolidine-2,5-dione derivatives with a dual affinity for serotonin 5-HT1A receptor and SERT

The serotonin 1A (5-HT1A) receptors and serotonin transporter (SERT) are important biological targets in the treatment of diseases of the central nervous system, especially for depression. In this study, new 3-(1H-indol-3-yl)pyrrolidine-2,5-dione derivatives linked with the 3-(1,2,3,6-tetrahydropyridin-4-yl)-1H-indole moiety were synthesised and evaluated for their affinity for 5-HT1A receptor and serotonin reuptake inhibition. Selected compounds were then tested for their affinity for D2, 5-HT2A, 5-HT6 and 5-HT7 receptors, and also in in vitro metabolic stability assays in human microsomes. Finally, in vivo assays allowed us to evaluate the agonist–antagonist properties of pre- and postsynaptic 5-HT1A receptors. 3-(1-(4-(3-(5-methoxy-1H-indol-3-yl)-2,5-dioxopyrrolidin-1-yl)butyl)-1,2,3,6-tetrahydropyridin-4-yl)-1H-indole-5-carbonitrile (4f) emerged as the most promising compound from the series, due to its favourable receptor binding profile (Ki(5-HT1A) = 10.0 nM; Ki(SERT) = 2.8 nM), good microsomal stability and 5-HT1A receptor agonistic activity.

Prepulse inhibition of the acoustic startle reflex impairment by 5-HT2A receptor activation in the inferior colliculus is prevented by GABAA receptor blockade in the pedunculopontine tegmental nucleus

The relationship between serotonin dysfunction and schizophrenia commenced with the discovery of the effects of lysergic acid diethylamide (LSD) that has high affinity for 5-HT2A receptors. Activation of these receptors produces perceptual and behavioural changes such as illusions, visual hallucinations and locomotor hyperactivity. Using prepulse inhibition (PPI) of the acoustic startle, which is impaired in schizophrenia,we aimed to investigate:i) the existence of a direct and potentially inhibitory neural pathway between the inferior colliculus (IC) and the pedunculopontine tegmental nucleus (PPTg) involved in the mediation of PPI responses by a neural tract tracing procedure;ii) if the microinjection of the 5-HT2A receptors agonist DOI in IC would activate neurons in this structure and in the PPTg by a c-Fos protein immunohistochemistry study;iii) whether the deficits in PPI responses, observed after the administration of DOI in the IC, could be prevented by the concomitant microinjection of the GABAA receptor antagonist bicuculline in the PPTg.Male Wistar rats were used in this study. An IC-PPTg reciprocated neuronal pathway was identified by neurotracing. The number of c-Fos labelled cells was lower in the DOI group in IC and PPTg, suggesting that this decrease could be due to the high levels of GABA in both structures. The concomitant microinjections of bicuculline in PPTg and DOI in IC prevented the PPI deficit observed after the IC microinjection of DOI. Our findings suggest that IC 5-HT2A receptors may be at least partially involved in the regulation of inhibitory pathways mediating PPI response in IC and PPTg structures.

Discovery of novel arylpiperazine-based DA/5-HT modulators as potential antipsychotic agents – Design, synthesis, structural studies and pharmacological profiling

Schizophrenia is a mental disorder with a complex pathomechanism involving many neurotransmitter systems. Among the currently used antipsychotics, classical drugs acting as dopamine D2 receptor antagonists, and drugs of a newer generation, the so-called atypical antipsychotics, can be distinguished. The latter are characterized by a multi-target profile of action, affecting, apart from the D2 receptor, also serotonin receptors, in particular 5-HT2A and 5-HT1A. Such profile of action is considered superior in terms of both efficacy in treating symptoms and safety. In the search for new potential antipsychotics of such atypical receptor profile, an attempt was made to optimize the arylpiperazine based virtual hit, D2AAK3, which in previous studies displayed an affinity for D2, 5-HT1A and 5-HT2A receptors, and showed antipsychotic activity in vivo. In this work, we present the design of D2AAK3 derivatives (1–17), their synthesis, and structural and pharmacological evaluation. The obtained compounds show affinities for the receptors of interest and their efficacy as antagonists/agonists towards them was confirmed in functional assays. For the selected compound 11, detailed structural studies were carried out using molecular modeling and X-ray methods. Additionally, ADMET parameters and in vivo antipsychotic activity, as well as influence on memory and anxiety processes were evaluated in mice, which indicated good therapeutic potential and safety profile of the studied compound.

New Piperazine Derivatives of 6-Acetyl-7-hydroxy-4-methylcoumarin as 5-HT1A Receptor Agents.

A series of 15 new derivatives of 6-acetyl-7-hydroxy-4-methylcoumarin containing a piperazine group were designed with the help of computational methods and were synthesized to study their affinity for the serotonin 5-HT1A and 5-HT2A receptors. Among them, 6-acetyl-7-{4-[4-(3-bromophenyl)piperazin-1-yl]butoxy}-4-methylchromen-2-one (4) and 6-acetyl-7-{4-[4-(2-chlorophenyl)piperazin-1-yl]butoxy}-4-methylchromen-2-one (7) exhibited excellent activity for 5-HT1A receptors with Ki values 0.78 (0.4-1.4) nM and 0.57 (0.2-1.3) nM, respectively, comparable to the Ki values of 8-OH-DPAT (0.25 (0.097-0.66) nM). The equilibrium dissociation constant values of the tested compounds showed differential intrinsic activities of the agonist and antagonist modes.

Binding and functional structure-activity similarities of 4-substituted 2,5-dimethoxyphenyl isopropylamine analogues at 5-HT2A and 5-HT2B serotonin receptors.

Certain 4-substituted analogs of 1-(2,5-dimethoxyphenyl)isopropylamine (2,5-DMA) are psychoactive classical hallucinogens or serotonergic psychedelic agents that function as human 5-HT2A (h5-HT2A) serotonin receptor agonists. Activation of a related receptor population, h5-HT2B receptors, has been demonstrated to result in adverse effects including cardiac valvulopathy. We previously published on the binding of several such agents at the two receptor subtypes. We hypothesized that, due to their structural similarity, the 5-HT2A and 5-HT2B receptor affinities of these agents might be related, and that QSAR studies might aid future studies. For a series of 13 compounds, it is demonstrated here that i) their published rat brain 5-HT2 receptor affinities are significantly correlated with their h5-HT2A (r = 0.942) and h5-HT2B (r = 0.916) affinities, ii) as with r5-HT2 receptor affinity, h5-HT2A affinity is correlated with the lipophilicity of the 4-position substituent (r = 0.798), iii) that eight of the ten compounds examined in functional (Ca+2 mobilization in stable cell lines generated expressing the human 5-HT2B receptor using the Flp-In T-REx system) assays acted as h5-HT2B agonists (4-substituent = H, F, Br, I, OCH2CH3, NO2, nC3H7, tC4H9) and two (n-hexyl and benzyl) as antagonists, iv) h5-HT2B affinity but not action was correlated with the lipophilicity of the 4-position substituent (r = 0.750; n = 10). The findings suggest that h5-HT2B receptor affinity, and its relationship to substituent lipophilicity, might be approximated by rat and h5-HT2A affinity but cannot be used as a predictor of h5-HT2B agonist action of 2,5-DMA analogs. Furthermore, given that certain 2,5-DMA analogs are on the clandestine market, their potential to produce cardiac side effects following persistent or chronic use via activation of h5-HT2B receptors should be considered.

HBK-15, a Multimodal Compound, Showed an Anxiolytic-Like Effect in Rats

Anxiety is a common mental disorder, and its prevalence has lately increased because of the COVID-19 pandemic. Unfortunately, the available anxiolytics are often ineffective, and most possess addictive potential. Thus, searching for novel compounds is essential. In our previous studies, we selected a multimodal compound, HBK-15, which showed a fast antidepressant-like effect in animal models of depression. HBK-15 demonstrated a high affinity for serotonin 5-HT1A receptors and moderate for 5-HT7, dopamine D2, and α1-adrenoceptors. Based on the receptor profile and preliminary studies, we aimed to investigate the anxiolytic potential of HBK-15 using the conditioned-response rat model of anxiety, i.e., the Vogel drinking test. We performed hot plate and free-drinking tests to exclude false positive results in the Vogel test. Using radioligand binding studies, we also investigated the affinity of the compound for the selected biological targets, which play a role in anxiety. Our experiments revealed that HBK-15 showed an anxiolytic-like effect in rats (5 mg/kg) without influencing the pain threshold or the amount of water consumed in the free-drinking test. Furthermore, the tested compound did not show a significant affinity for the selected biological targets, which suggests that its anxiolytic-like mechanism of action could be connected with the interaction with other receptors. This study indicates that multimodal compounds with a receptor profile similar to HBK-15 could be an attractive therapeutic option for patients with a generalized anxiety disorder. However, more studies are required to determine the exact mechanism of action of HBK-15 and its safety profile.

Chromenes - A Novel Class of Heterocyclic Compounds: Recent Advancements and Future Directions.

Chromenes are an important class of oxygen-containing heterocyclic compounds with intriguing biological activity, a simple structure with mild adverse effects. Chromenes are abundantly found in nature in the form of alkaloids, tocopherols, flavone, and anthocyanins. The Chromene nucleus is an important moiety for the discovery of new drug candidates. Chromene derivatives have shown various pharmacological activities like antiviral, anticancer, anti-inflammatory, antitumour, antimicrobial, antiproliferative, anticholinesterase, EPR-1 (Effector cell Protease Receptor-1) antagonist and MAO (Mono-Amine Oxidase) inhibitors. In SAR (Structure Activity Relationship) studies with chromene nucleus, it was found that 4-aryl moiety, 3-cyano group, and 2-amino group are essential for the cytotoxic activity. Substitution at the 7th position with electron donating group enhances the pharmacological activity whereas the electron withdrawing group decreases the pharmacological activity. Structural modifications at the chromene ring, middle aliphatic portion, and terminal aromatic ring yielded more potential 5-HT1A (5-Hydroxytryptamine 1A) receptor affinity and antidiabetic activity. Chromenes with cyclic secondary amine and 4-hydroxy phenyl substituents yielded potent antimicrobial compounds. This review summarizes the importance of chromenes in rational drug design and the development of novel molecules with a variety of pharmacological activities.

Synthesis and antidepressant activity of novel 1-(1-benzoylpiperidin-4-yl) methanamine derivatives selectively targeting SSRI/5-HT1A

A series of novel 1-(1-benzoylpiperidin-4-yl) methanamine derivatives were synthesized and evaluated for the serotonin reuptake inhibitory abilities and binding affinities to the 5-HT1A receptor. The metabolic stabilities of these compounds were measured in vitro using human or mouse liver microsomes and the antidepressant activities were explored In vivo using the forced swimming test (FST) and tail suspension test (TST) in mice. The results indicated that the compound 12a exhibited strongest serotonin reuptake inhibition (IC50 = 8.2 nM) and marked 5-HT1A receptor affinity (Ki = 0.069 nM), which were significantly superior to lead compounds Ⅰ and Ⅱ. Meanwhile, compound 12a showed good metabolic stability in vitro and exhibited potential antidepressant-like effects in the FST and TST in mice.

Treatment of Cognitive Impairment in Schizophrenia

Cognitive function in schizophrenia is one of the main elements significantly related to functional outcomes, accounting for approximately 25–50% of the variance in real-world functioning. Treatment approaches to cognitive dysfunctions include both pharmacological and psychosocial interventions. Second Generation Antipsychotics (SGAs) may partially improve cognitive dysfunction, due to their relatively high affinity for serotonin 5HT2A receptors. The effects of glutamatergic agents indicated benefits on cognition of a group of amino acids that act as glutamate agonists by binding to the glycine site on NMDA receptors. The administration of muscarinic antagonists potentiates cognitive impairments, while the α7 nicotinic acetylcholine receptors have been shown to play an important role in cognition with potential therapeutic applications in schizophrenia. Studies on drugs targeting neuroinflammation and oxidative stress emerged. Cognitive remediation has proved to be effective in improving cognitive dysfunctions and psychosocial functioning in people with schizophrenia, however there is still a limited understanding of how the putative active therapy ingredients contribute to changes in the brain and translate into improved real-world functioning. Cogrem exerts its maximal benefit when delivered in the context of other psychiatric rehabilitative interventions, but it is not yet clear what are the mechanisms of effectiveness of integrated treatment. It is important that future research shift from studies of group efficacy to individual efficacy of treatments, in the perspective of precision medicine. Issues related to individual predictors of effectiveness and of interactions between specific pharmacologic, specific cognitive remediation technique and individual patients’ characteristics should be furtherly addressed.DisclosureIn the last two years, Prof Vita received, directly or indirectly, support for clinical studies or trials, conferences, consultancies, Congress presentations, advisory boards from: Angelini, Boehringer Ingelheim, Innovapharma, Janssen-Cilag, Lundbeck,

Cellular and Biochemical Studies on Risperidone Induced Teratogenesis in Developing Chick Embryos

Risperidone is a second-generation antipsychotic drug that exhibits D2, 5-HT2A, α1, α2, and H1 receptor affinity. Patients suffering from Schizophrenia are prescribed with this drug. It is mostly used for controlling the overactivity of the central mesolimbic and mesocortical pathways of the patients. According to the studies conducted it has been found that Risperidone possesses teratogenic actions on various model organisms. Consumption of this antipsychotic drug is not only associated with behavioural changes but also with physical alterations. It increases the risk by elevating nitric oxide levels and activating macrophages which leads to apoptotic events in the viable cells. Furthermore, it has been established that Risperidone toxicity caused due to overdose induces neurological as well as cardiovascular defects. Risperidone has the ability to cross the placental barrier and reach the foetal bloodstream intuitively. In addition, Risperidone also gets distributed in the milk of a lactating mother leading to undesirable changes in the breastfed babies. Here in this study, we have shown that Gallus gallus domesticus embryos (HH 23-26) treated with a minimum dose of Risperidone (1000 ppm) altered the protein and enzyme biochemistry with respect to total protein content, alkaline phosphatase (ALP), and Acetylcholinesterase levels. Cell viability studies conducted using flowcytometry have indicated its possible role in the induction of apoptosis as well as necrosis in a developing chick embryo. The present study provides insight into the effects of Risperidone that it may possess on gestating and lactating women. The study also explains the teratogenic potential of Risperidone on target and non-target organisms.

Monoamine Receptor and Transporter Interaction Profiles of 4‐Alkyl‐Substituted 2,5‐Dimethoxyamphetamines

BackgroundVarious ring‐substituted phenethylamines and amphetamines are used recreationally due to their mind‐altering effects. Furthermore, such psychedelic substances have recently gained increased interest as prospective therapeutics. Here, we studied the pharmacological properties of 4‐alkylated 2,5‐dimethoxyamphetamines in vitro. Specifically, we assessed the effect of the 4‐alkyl chain length on interactions with monoaminergic targets. We aimed to test the hypothesis that the derivatives with the highest clinical potency display the most potent serotonin (5‐HT) type 2A receptor interactions, which is the key driver of psychedelic effects.MethodsWe determined binding affinities of 2,5‐dimethoxyamphetamine (2,5‐DMA), 4‐methyl‐2,5‐dimethoxyamphetamine (DOM), 4‐ethyl‐2,5‐dimethoxyamphetamine (DOET), 4‐butyl‐2,5‐dimethoxyamphetamine (DOBU), and 4‐amyl‐2,5‐dimethoxyamphetamine (DOAM) at serotonergic, adrenergic, and dopaminergic receptors and transporters, as well as at the trace amine‐associated receptor 1 (TAAR1). For this, we assessed radioligand displacement using cell membrane preparations expressing the respective targets. Furthermore, we determined the functional activity of the derivatives at the 5‐HT2A and 5‐HT2B receptors by measuring calcium mobilization and at the TAAR1 by measuring cAMP accumulation. In addition, we assessed whether any of the derivatives inhibit transporter‐mediated uptake of radiolabeled monoamines.ResultsUnlike 2,5‐DMA, its 4‐alkylated derivatives displayed potent (i.e., nanomolar) affinity at 5‐HT2A and 5‐HT2C receptors. Increasing length of the 4‐alkyl chain increased the selectivity for 5‐HT2A vs. 5‐HT1A and 5‐HT2C receptors. Whereas DOM and DOET activated the 5‐HT2B receptor as partial agonists in the nanomolar range (EC50: 68–128 nM, Emax: 73–85%), DOBU and DOAM did not activate the receptor at investigated concentrations (EC50 > 10,000 nM). In contrast to the potent interactions with 5‐HT2 receptors, the 4‐alkyl‐substituted 2,5‐dimethoxyamphetamines did not or only weakly (i.e., in the micromolar range) interact with other monoaminergic targets.ConclusionAmong the tested substances, user reports suggest DOM and DOET to be the only derivatives with a distinct psychedelic effect profile. Our data therefore indicate that 5‐HT2A and 5‐HT2C receptor affinity alone is not a sufficient predictor for the clinical and psychedelic potency of 4‐substituted 2,5‐dimethoxyamphetamines. To assess the clinical potential of the tested substances, future studies should focus in more detail on pharmacokinetics and qualitative differences in 5‐HT2 receptor activation.

Design, Synthesis, and Antidepressant Activity Study of Novel Aryl Piperazines Targeting Both 5-HT1A and Sigma-1 Receptors

A total of 20 novel aryl piperazine derivatives were designed and synthesized, and their structures were confirmed by mass spectrometry and nuclear magnetic resonance analyses. Their 5-HT1A and sigma-1 receptor affinities were determined, and six of them showed high affinities (K i < 20 nmol/L) to both 5-HT1A and sigma-1 targets. Then, metabolic stability (T 1/2) tests of six compounds in rat and human liver microsomes were performed. Our data indicated that compound 27 has both high affinity for 5-HT1A and sigma-1 receptors (5-HT1A: K i = 0.44 nmol/L; sigma-1: K i = 0.27 nmol/L), and good metabolic stability (T 1/2 values are 21.7 and 24.6 minutes, respectively). Interestingly, results from the forced swimming test, mouse tail suspension test, and preliminary pharmacokinetic test suggested the marked antidepressant activity, good pharmacokinetic characteristics, and low toxicity of compound 27 in the two models. In conclusion, compound 27 has great value of further study as an active molecule of antidepressant drugs.

A narrative synthesis of research with 5-MeO-DMT.

Background:5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a naturally occurring, short-acting psychedelic tryptamine, produced by a variety of plant and animal species. Plants containing 5-MeO-DMT have been used throughout history for ritual and spiritual purposes. The aim of this article is to review the available literature about 5-MeO-DMT and inform subsequent clinical development.Methods:We searched PubMed database for articles about 5-MeO-DMT. Search results were cross-checked against earlier reviews and reference lists were hand searched. Findings were synthesised using a narrative synthesis approach. This review covers the pharmacology, chemistry and metabolism of 5-MeO-DMT, as well epidemiological studies, and reported adverse and beneficial effects.Results:5-MeO-DMT is serotonergic agonist, with highest affinity for 5-HT1A receptors. It was studied in a variety of animal models, but clinical studies with humans are lacking. Epidemiological studies indicate that, like other psychedelics, 5-MeO-DMT induces profound alterations in consciousness (including mystical experiences), with potential beneficial long-term effects on mental health and well-being.Conclusion:5-MeO-DMT is a potentially useful addition to the psychedelic pharmacopoeia because of its short duration of action, relative lack of visual effects and putatively higher rates of ego-dissolution and mystical experiences. We conclude that further clinical exploration is warranted, using similar precautions as with other classic psychedelics.

Paliperidone to Treat Psychotic Disorders.

Purpose of Review: This is a comprehensive review of the literature regarding the use of paliperidone in the treatment of schizophrenia and schizoaffective disorder. It covers the background and presentation of schizophrenia and schizoaffective disorder, as well as the mechanism of action and drug information for paliperidone. It covers the existing evidence of the use of paliperidone for the treatment of schizophrenia and schizoaffective disorder. Recent Findings: Schizophrenia and schizoaffective disorder lead to significant cognitive impairment. It is thought that dopamine dysregulation is the culprit for the positive symptoms of schizophrenia and schizoaffective disorder. Similar to other second-generation antipsychotics, paliperidone has affinity for dopamine D2 and serotonin 5-HT2A receptors. Paliperidone was granted approval in the United States in 2006 to be used in the treatment of schizophrenia and in 2009 for schizoaffective disorder. Summary: Schizophrenia and schizoaffective disorder have a large impact on cognitive impairment, positive symptoms and negative symptoms. Patients with either of these mental illnesses suffer from impairments in everyday life. Paliperidone has been shown to reduce symptoms of schizophrenia and schizoaffective disorder.

β-adrenoceptor antagonists and nightmares: A pharmacoepidemiological-pharmacodynamic study.

To compare different β-adrenoceptor antagonists for the risk of reporting nightmare. The study involved two approaches: first, we investigated in VigiBase®, the World Health Organization Individual Case Safety Report (ICSR) database, the disproportionality between exposure to each β-adrenoceptor antagonists and reports of nightmares between 1967 and 2019. Second, in a pharmacoepidemiological-pharmacodynamic analysis, we assessed whether use of β-adrenoceptor antagonists with moderate and high lipid solubility or strong 5-HT1A affinity were associated with an increased risk of reporting nightmares. We conducted multivariate logistic regression to estimate reporting odds ratios (RORs) of nightmares compared to all other adverse drug reactions. Of the 126,964 reports recorded with β-adrenoceptor antagonists, 1138 (0.9%) were nightmares. The highest risk of reporting a nightmare was found with exposure of pindolol (adjusted ROR 2.82, 95%CI, 2.19-3.61), metoprolol (1.89, 1.66-2.16), and alprenolol (1.77, 1.06-2.97). Compared to use of low lipid solubility β-adrenoceptor antagonists, use of moderate or high lipid solubility β-adrenoceptor antagonists were significantly more associated with nightmare reports (aROR moderate vs. low 1.72, 95%CI 1.47-2.00 and aROR high vs. low 1.84, 95%CI 1.53-2.22). Use of moderate or high 5-HT1A affinity of β-adrenoceptor antagonists was associated with an increased ROR of nightmares compared with low 5-HT1A affinity of β-adrenoceptor antagonists (aROR moderate vs. low 1.22, 95%CI 1.04-1.43 and aROR high vs. low 2.46, 95%CI 1.93-3.13). In our large pharmacovigilance study, nightmares are more frequently reported for pindolol and metoprolol, and among β-adrenoceptor antagonists with high lipid solubility and high 5-HT1A receptor affinity.

A new class of 5-HT1A receptor antagonists with procognitive and antidepressant properties.

Aims: 5-HT1A receptor antagonists constitute a potential group of drugs in the treatment of CNS diseases. The aim of this study was to search for new procognitive and antidepressant drugs among amide derivatives of aminoalkanoic acids with 5-HT1A receptor antagonistic properties. Materials & methods: Thirty-three amides were designed and evaluated in silico for their drug-likeness. The synthesized compounds were tested in vitro for their 5-HT1A receptor affinity and functional profile. Moreover, their selectivity over 5-HT7, 5-HT2Aand D2 receptors and ability to inhibit phosphodiesterases were evaluated. Results:A selected 5-HT1A receptor antagonist 20 (Ki=35nM, Kb=4.9nM) showed procognitive and antidepressant activity in vivo. Conclusion: Novel 5-HT1A receptor antagonists were discovered and shown as potential psychotropic drugs.

Experimental and computational structural studies of 5-substituted-3-(1-arylmethyl-1,2,3,6-tetrahydropyridin-4-yl)-1H-indoles

Four compounds (1–4) reported in our previous work as potential antipsychotics with affinity for dopamine D2 and serotonin 5-HT1A and 5-HT2A receptors, were now subjected to detailed structural characterization. The X-ray analysis conducted for studied compounds proved that interatomic distances and bond angles in their crystal structures lie within normal values. The indole group in all compounds is planar, whereas tetrahydropyridine moiety exhibits almost ideal or close to half-chair conformation and is slightly or significantly rotated in relation to the indole group plane by 9.49(1)°, 30.24(11)°, 7.43(6)° and 15.98(18)° in compounds 1–4, respectively. The R1 substituents of tetrahydropyridine group in all cases form a dihedral angle with the indole moiety with value ranging from 66.57(14)° (2) to 86.73(17)° (4). The crystal structure of 1 is stabilized by N–H···N hydrogen bonds and C–H···π interactions. The intermolecular C(12)−H(12B)···Cg(2) interactions form a supramolecular two-dimensional network. The molecules in the crystal of 2 are linked by N–H···N. The formed chains are additionally stabilized with C–H···S hydrogen bonds. In case of compound 3, molecule chains are formed by N–H···N hydrogen bonds and are further linked via C–H···O hydrogen bonds into layer. The crystal structure is also stabilized by intermolecular C–H···π interactions. The molecules of compound 4 are linked by N–H···N hydrogen bonds and further stabilized by intermolecular C–H···π interactions. Crystallographic analysis was complemented with computational studies, such as Frontier Molecular Orbital analysis, which indicated that all four compounds display similar chemical reactivity, regardless of different R1 and R2 substituents. In addition, the most reactive parts of the compounds appear to be the indole and double bond located in tetrahydropyridine moiety. Lastly, the calculations of electrostatic potential and non-covalent interactions have been performed.

Novel serotonin 5-HT2A receptor antagonists derived from 4-phenylcyclohexane-5-spiro-and 5-methyl-5-phenyl-hydantoin, for use as potential antiplatelet agents

BackgroundAntiplatelet drugs have been used in the treatment of acute coronary syndromes and for the prevention of recurrent events. Unfortunately, many patients remain resistant to the available antiplatelet treatment. Therefore, there is a clinical need to synthesize novel antiplatelet agents, which would be associated with different pathways of platelet aggregation, to develop an alternative or additional treatment for resistant patients. Recent studies have revealed that 5-HT2A receptor antagonists could constitute alternative antiplatelet therapy.MethodsBased on the structures of the conventional 5-HT2A receptor ligands, two series of compounds with 4-phenylcyclohexane-5-spiro- or 5-methyl-5-phenyl-hydantoin core linked to various arylpiperazine moieties were synthesized and their affinity for 5-HT2A receptor was assessed. Further, we evaluated their antagonistic potency at 5-HT2A receptors using isolated rat aorta and cells expressing human 5-HT2A receptors. Finally, we studied their anti-aggregation effect and compared it with ketanserin and sarpogrelate, the reference 5-HT2A receptor antagonists. Moreover, the structure–activity relationships were studied following molecular docking to the 5-HT2A receptor model.ResultsFunctional bioassays revealed some of the synthesized compounds to be moderate antagonists of 5-HT2A receptors. Among them, 13, 8-phenyl-3-(3-(4-phenylpiperazin-1-yl)propyl)-1,3-diazaspiro[4.5]decane-2,4-dione, inhibited collagen stimulated aggregation (IC50 = 27.3 μM) being more active than sarpogrelate (IC50 = 66.8 μM) and comparable with ketanserin (IC50 = 32.1 μM). Moreover, compounds 2–5, 9–11, 13, 14 inhibited 5-HT amplified, ADP- or collagen-induced aggregation.ConclusionsOur study confirmed that the 5-HT2A antagonists effectively suppress platelet aggregation and remain an interesting option for the development of novel antiplatelet agents with an alternative mechanism of action.

Relationship between clozapine dose and severity of obsessive-compulsive symptoms

Evidence supports the fact that clozapine can induce stressful obsessive–compulsive symptoms (OCS). Although clozapine’s robust inhibition of serotonergic neurotransmission is believed to be a key mechanism underlying clozapine-induced OCS, the exact mechanism(s) are not fully understood. Intuitively, it is reasonable to believe that the dose of clozapine is likely related to emergent OCS severity. However, there is conflicting evidence where both positive and inverse relationships have been demonstrated between clozapine dose and emergent OCS severity. Upon examination of clozapine’s receptor profile, in particular its affinity for 5-HT2A and D2 receptors, we hypothesize that there is a biphasic relationship between clozapine dose and emergent OCS severity. We present here a preliminary analysis of published cases in the literature to support our hypothesis.