Novel benzothiazole derivatives as multitargeted-directed ligands for the treatment of Alzheimer's disease.

Neurodegenerative diseases such as Alzheimer's disease (AD) are multifactorial with several different pathologic mechanisms. Therefore, it is assumed that multitargeted-directed ligands (MTDLs) which interact with different biological targets relevant to the diseases, might offer an improved therapeutic alternative than using the traditional "one-target, one-molecule" approach. Herein, we describe new benzothiazole-based derivatives as a privileged scaffold for histamine H3 receptor ligands (H3R). The most affine compound, the 3-(azepan-1-yl)propyloxy-linked benzothiazole derivative 4b, displayed a Ki value of 0.012 µM. The multitargeting potential of these H3R ligands towards AChE, BuChE and MAO-B enzymes was evaluated to yield compound 3s (pyrrolidin-1-yl-(6-((5-(pyrrolidin-1-yl)pentyl)oxy)benzo[d]thiazol-2-yl)methanone) as the most promising MTDL with a Ki value of 0.036 µM at H3R and IC50 values of 6.7 µM, 2.35 µM, and 1.6 µM towards AChE, BuChE, and MAO-B, respectively. These findings suggest that compound 3s can be a lead structure for developing new multi-targeting anti-AD agents.

Multitargeting Histamine H3 Receptor Ligands among Acetyl- and Propionyl-Phenoxyalkyl Derivatives.

Alzheimer's disease (AD) is a neurodegenerative disorder, for which there is no effective cure. Current drugs only slow down the course of the disease, and, therefore, there is an urgent need to find effective therapies that not only treat, but also prevent it. Acetylcholinesterase inhibitors (AChEIs), among others, have been used for years to treat AD. Histamine H3 receptors (H3Rs) antagonists/inverse agonists are indicated for CNS diseases. Combining AChEIs with H3R antagonism in one structure could bring a beneficial therapeutic effect. The aim of this study was to find new multitargetting ligands. Thus, continuing our previous research, acetyl- and propionyl-phenoxy-pentyl(-hexyl) derivatives were designed. These compounds were tested for their affinity to human H3Rs, as well as their ability to inhibit cholinesterases (acetyl- and butyrylcholinesterases) and, additionally, human monoamine oxidase B (MAO B). Furthermore, for the selected active compounds, their toxicity towards HepG2 or SH-SY5Y cells was evaluated. The results showed that compounds 16 (1-(4-((5-(azepan-1-yl)pentyl)oxy)phenyl)propan-1-one) and 17 (1-(4-((6-(azepan-1-yl)hexyl)oxy)phenyl)propan-1-one) are the most promising, with a high affinity for human H3Rs (Ki: 30 nM and 42 nM, respectively), a good ability to inhibit cholinesterases (16: AChE IC50 = 3.60 µM, BuChE IC50 = 0.55 µM; 17: AChE IC50 = 1.06 µM, BuChE IC50 = 2.86 µM), and lack of cell toxicity up to 50 µM.

BOPPY-based novel fluorescent dopamine D2 and D3 receptor ligands.

Dopamine is one of the crucial neurotransmitters in the human brain. Its out-of-range concentration can lead to various neurological diseases with special interest for dopamine D2 and D3 receptor subtypes. Although BODIPY is a highly versatile structural moiety for fluorescence labeling, we have looked out for structurally related pyridine-based moieties. We used BOPPY labelling of well-described D2R/D3R pharmacophores to obtain ligands with moderate to low nanomolar binding affinities as well as low to excellent quantum yields for bright fluorescence ligands. To best of our knowledge, this is the first report on the application of BOPPY fluorophores to GPCR ligands. This approach offers a general applicable way for fluorescence labelling via primary aliphatic amine elements.

Design and Synthesis of Arylpiperazine Serotonergic/Dopaminergic Ligands with Neuroprotective Properties.

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 compound 9b that has an affinity profile consistent with studies in the context of ASD (5-HT1AKi = 23.9 nM, 5-HT2AKi = 39.4 nM, 5-HT7Ki = 45.0 nM). Both compounds also had antioxidant properties. All compounds showed low in vitro metabolic stability, the only exception being compound 9b, which might be suitable for studies in vivo.

The Multi-Targeting Ligand ST-2223 with Histamine H3 Receptor and Dopamine D2/D3 Receptor Antagonist Properties Mitigates Autism-Like Repetitive Behaviors and Brain Oxidative Stress in Mice.

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 observed in an open field test (all p < 0.05), but did not restore the hyperactivity parameters, whereas MEM failed to restore mouse anxiety and hyperactivity. In addition, ST-2223 (5 mg/kg, i.p.) mitigated oxidative stress status by decreasing the elevated levels of malondialdehyde (MDA), and increasing the levels of decreased glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) in different brain parts of treated BTBR mice (all p < 0.05). These preliminary in vivo findings demonstrate the ameliorative effects of ST-2223 on RRBs in a mouse model of ASD, suggesting its pharmacological prospective to rescue core ASD-related behaviors. Further confirmatory investigations on its effects on various brain neurotransmitters, e.g., dopamine and histamine, in different brain regions are still warranted to corroborate and expand these initial data.

Discovery of a Small Molecule Activator of Slack (Kcnt1) Potassium Channels That Significantly Reduces Scratching in Mouse Models of Histamine-Independent and Chronic Itch.

Various disorders are accompanied by histamine-independent itching, which is often resistant to the currently available therapies. Here, it is reported that the pharmacological activation of Slack (Kcnt1, KNa1.1), a potassium channel highly expressed in itch-sensitive sensory neurons, has therapeutic potential for the treatment of itching. Based on the Slack-activating antipsychotic drug, loxapine, a series of new derivatives with improved pharmacodynamic and pharmacokinetic profiles is designed that enables to validate Slack as a pharmacological target in vivo. One of these new Slack activators, compound 6, exhibits negligible dopamine D2 and D3 receptor binding, unlike loxapine. Notably, compound 6 displays potent on-target antipruritic activity in multiple mouse models of acute histamine-independent and chronic itch without motor side effects. These properties make compound 6 a lead molecule for the development of new antipruritic therapies targeting Slack.

The Novel Pimavanserin Derivative ST-2300 with Histamine H3 Receptor Affinity Shows Reduced 5-HT2A Binding, but Maintains Antidepressant- and Anxiolytic-like Properties in Mice.

The therapy of depression is challenging and still unsatisfactory despite the presence of many antidepressant drugs on the market. Consequently, there is a continuous need to search for new, safer, and more effective antidepressant therapeutics. Previous studies have suggested a potential association of brain histaminergic/serotoninergic signaling and antidepressant- and anxiolytic-like effects. Here, we evaluated the in vivo antidepressant- and anxiolytic-like effects of the newly developed multiple-active ligand ST-2300. ST-2300 was developed from 5-HT2A/2C inverse agonist pimavanserin (PIM, ACP-103) and incorporates a histamine H3 receptor (H3R) antagonist pharmacophore. Despite its parent compound, ST-2300 showed only moderate serotonin 5-HT2A antagonist/inverse agonist affinity (Ki value of 1302 nM), but excellent H3R affinity (Ki value of 14 nM). In vivo effects were examined using forced swim test (FST), tail suspension test (TST), and the open field test (OFT) in C57BL/6 mice. Unlike PIM, ST-2300 significantly increased the anxiolytic-like effects in OFT without altering general motor activity. In FST and TST, ST-2300 was able to reduce immobility time similar to fluoxetine (FLX), a recognized antidepressant drug. Importantly, pretreatment with the CNS-penetrant H3R agonist (R)-α-methylhistamine reversed the antidepressant-like effects of ST-2300 in FST and TST, but failed to reverse the ST-2300-provided anxiolytic effects in OFT. Present findings reveal critical structural features that are useful in a rational multiple-pharmacological approach to target H3R/5-HT2A/5-HT2C.

Autodisplay of human PIP5K1α lipid kinase on Escherichia coli and inhibitor testing.

The human phosphatidylinositol 4-phosphate 5-kinase type I α (hPIP5K1α) plays a major role in the PI3K/AKT/mTOR signaling pathway. As it has been shown before that hPIP5K1α is involved in the development of different types of cancer in particular prostate cancer, inhibitors of the enzyme might be a new option for the treatment of this disease. Here we report on the expression of hPIP5K1α on the surface of E. coli using Autodisplay. Autodisplay is defined as the surface display of a recombinant protein on a gramnegative bacterium by the autotransporter secretion pathway. After verification of surface expression, enzyme activity of whole cells displaying hPIP5K1α was determined by a capillary electrophoresis based assay. When using cells at an OD578 of 2.5, the artificial substrate phosphatidylinositol4-phosphate (PI(4)P) fluorescein was converted by a rate of 10.7 ±â€¯0.2 fmol/min. Using this substrate inhibition of three pyranobenzoquinone type compounds was tested. The most active compound was 4-(2-amino-3-cyano-6-hydroxy-5,8-dioxo-7-undecyl-5,8-dihydro-4H-chromen-4-yl) benzoic acid with an IC50 value of 8.6 µM. Because until now, all attempts to purify hPIP5K1α failed, we suggest the use of whole cells of E. coli displaying the enzyme as a convenient tool for inhibitor identification.

Guanidine Derivatives: How Simple Structural Modification of Histamine H3R Antagonists Has Led to the Discovery of Potent Muscarinic M2R/M4R Antagonists.

This article describes the discovery of novel potent muscarinic receptor antagonists identified during a search for more active histamine H3 receptor (H3R) ligands. The idea was to replace the flexible seven methylene linker with a semirigid 1,4-cyclohexylene or p-phenylene substituted group of the previously described histamine H3R antagonists ADS1017 and ADS1020. These simple structural modifications of the histamine H3R antagonist led to the emergence of additional pharmacological effects, some of which unexpectedly showed strong antagonist potency at muscarinic receptors. This paper reports the routes of synthesis and pharmacological characterization of guanidine derivatives, a novel chemotype of muscarinic receptor antagonists binding to the human muscarinic M2 and M4 receptors (hM2R and hM4R, respectively) in nanomolar concentration ranges. The affinities of the newly synthesized ADS10227 (1-{4-{4-{[4-(phenoxymethyl)cyclohexyl]methyl}piperazin-1-yl}but-1-yl}-1-(benzyl)guanidine) at hM2R and hM4R were 2.8 nM and 5.1 nM, respectively.