Phosphodiesterase 10A Inhibitors Research Articles

Discovery of a pyrazolo[1,5-a]pyrimidine derivative (MT-3014) as a highly selective PDE10A inhibitor via core structure transformation from the stilbene moiety

We have developed a new class of PDE10A inhibitor, a pyrazolo[1,5-a]pyrimidine derivative MT-3014 (1). A previous compound introduced was deprioritized due to concerns for E/Z-isomerization and glutathione-adduct formation at the core stilbene structure. We discovered pyrazolo [1,5-a] pyrimidine as a new lead scaffold by structure-based drug design utilizing a co-crystal structure with PDE10A. The lead compound was optimized for in vitro activity, solubility, and selectivity against human ether-á-go-go related gene cardiac channel binding. We observed that MT-3014 shows excellent efficacy in rat conditioned avoidance response test and suitable pharmacokinetic properties in rats, especially high brain penetration.

Molecular docking and receptor-based QASR studies on pyrimidine derivatives as potential phosphodiesterase 10A inhibitors

In the present work, molecular docking methodology in combination with quantitative structure–activity relationship (QSAR) was employed to predict the inhibition activity of 87 structurally diverse pyrimidine-based derivatives as phosphodiestrae10A (PDE10A) inhibitors due to their potential in the treatment of schizophrenia. In this method, compounds in their preferred enzyme-docked conformations were utilized to derive interaction-based quantitative descriptors in order to explain reported PDE10A inhibitory activities. Multiple linear regression (MLR), artificial neural network (ANN), and least square support vector regression (LS-SVR) were exploited to developing the structure-based quantitative structure–activity relationship models. Among these models, LS-SVR model showed more satisfactory statistical parameters with regard to both internal (Rtrain = 0.951, Q2 = 0.804, RMSEtrain = 0.494) and external validation (Rtest = 0.941, RMSEtest = 0.549) test results. Information from the most relevant descriptors suggests that incorporating steric effect, electronegativity, and the number of substituted aromatic carbon correlate the activity with structural features of the studied compounds. Molecular docking analysis of the most potent inhibitor explored that hydrogen bond formation and hydrophobicity participated in the binding interaction of PDE10A complex active pocket which these findings are in line with those obtained from QSAR model. The reliability assessment of compounds predictions was checked by model applicability domain (AD) analysis.

Discovery of two novel hetero-tricyclic lead scaffolds as PDE5A inhibitor: virtual screening, molecular docking and pharmacophore modeling approach

Phosphodiesterase 5A enzyme has been the upcoming and promising target in hypertension management. In this research, reported 270 bioactive natural products having antihypertensive potential were selected and docked against PDE5A using vLife MDS 4.6 software. Based on docking score, π-stacking, H-bond and ionic interactions with PDE5A, 82 tricyclic compounds were selected for further study. Protein residue Gln817A was associated in H-boding, Leu804A in ionic interaction whereas Val782A and Phe820A were associated in π-stacking interaction with ligand. In silico docking studies resulted in discovery of oxygen containing naphthofuran and nitrogen and oxygen containing pyrano quinolizine tricyclic lead scaffolds as novel PDE5A inhibitors. Additionally, developed pharmacophore model suggested that one centre of hydrogen bond acceptor, one aromatic centre and two aliphatic centres are minimum pharmacophoric features required in the molecule so as to show sildenafil like activity. The identified lead scaffolds would provide novel platform for drug discovery of bioactive natural products.

Phosphodiesterase 10A levels are related to striatal function in schizophrenia: a combined positron emission tomography and functional magnetic resonance imaging study

Pharmacological inhibition of phosphodiesterase 10A (PDE10A) is being investigated as a treatment option in schizophrenia. PDE10A acts postsynaptically on striatal dopamine signaling by regulating neuronal excitability through its inhibition of cyclic adenosine monophosphate (cAMP), and we recently found it to be reduced in schizophrenia compared to controls. Here, this finding of reduced PDE10A in schizophrenia was followed up in the same sample to investigate the effect of reduced striatal PDE10A on the neural and behavioral function of striatal and downstream basal ganglia regions. A positron emission tomography (PET) scan with the PDE10A ligand [11C]Lu AE92686 was performed, followed by a 6 min resting-state magnetic resonance imaging (MRI) scan in ten patients with schizophrenia. To assess the relationship between striatal function and neurophysiological and behavioral functioning, salience processing was assessed using a mismatch negativity paradigm, an auditory event-related electroencephalographic measure, episodic memory was assessed using the Rey auditory verbal learning test (RAVLT) and executive functioning using trail-making test B. Reduced striatal PDE10A was associated with increased amplitude of low-frequency fluctuations (ALFF) within the putamen and substantia nigra, respectively. Higher ALFF in the substantia nigra, in turn, was associated with lower episodic memory performance. The findings are in line with a role for PDE10A in striatal functioning, and suggest that reduced striatal PDE10A may contribute to cognitive symptoms in schizophrenia.

Effect of phosphodiesterase (1B, 2A, 9A and 10A) inhibitors on central nervous system cyclic nucleotide levels in rats and mice

Phosphodiesterase (PDE) inhibition has been broadly investigated as a target for a wide variety of indications including central nervous system (CNS) disorders. Cyclic nucleotide (cNT) changes within associated tissues may serve as a biomarker of PDE inhibition. We recently developed robust sample harvesting and bioanalytical methods to quantify cNT levels in rodent brain and cerebrospinal fluid (CSF). Herein, we report on the application of those methods to study rodent species-specific and rodent brain region-specific cNT changes following individual or concomitant PDE inhibitor administration.Male Sprague Dawley (Crl:CD® [SD]) rats were dosed subcutaneously (sc) with a PDE1B inhibitor (DNS-0056), a PDE2A inhibitor (PF-05180999), a PDE9A inhibitor (PF-4447943), and a PDE10A inhibitor (MP10), each at a single dose of 10 or 30 mg/kg, or concomitantly with all 4 inhibitors at 10 mg/kg each. Male Carworth Farms (Crl:CF1 ®[CF-1]) mice were dosed intraperitoneally (ip) with the four individual inhibitors at a single dose of 10 mg/kg or concomitantly with all 4 inhibitors at 10 mg/kg each. The doses studied are generally adequate for affecting measurable cNT levels in the tissues of interest and were thereby chosen for this investigation. Measured 3′,5′-cyclic adenosine monophosphate (cAMP) changes were generally statistically insignificant in the brain, striatum and CSF after administration of the aforementioned PDE inhibitors. However, the levels of 3′,5′-cyclic guanosine monophosphate (cGMP) increased in both rat and mouse striatum (2.2-, 2.1- and 1.7-fold and 6.4-, 2.8- and 1.7-fold, respectively) after PDE2A, 9A, and 10A inhibitor dosing. In all cases, the cNT changes followed the same trend in the brain, striatum and CSF after PDE inhibitor dosing and dose response was observed in rats. Concomitant treatment with PDE1B, PDE2A, PDE9A and PDE10A inhibitors resulted in a 4.4- and 36.7-fold increase of cGMP in rat and mouse striatum. The drug exposures after concomitant treatment were also higher than in the individual inhibitor-treated animals. cGMP enhancement observed could be due to synergistic effects, though an additive effect of the combined inhibitor concentrations may also contribute.

Novel Pyrazolo[4, 3-c]Quinolin-3-One Derivatives as PDE5A Inhibitors.

PDE5A is a phosphodiesterase which specifically hydrolyzes the cGMP to GMP. It takes part in several physiological and pathological pathways and is considered an important drug target. Currently, PDE5 inhibitors (ex; Sildenafil, Tadalafil) available in the market are not only being used for the treatment of erectile dysfunction but at the same time, they are also in clinical trials being investigated as anticancer agents. In this work, we have examined pyrazolo [4,3-c]quinolin-3-ones as PDE5A inhibitors. Pyrazolo [4,3-c]quinolin-3-ones are the class of tricyclic heterocyclic derivatives having a variety of therapeutically interesting drug candidates known for their anti-inflammatory, anti-viral, anti-anxiety and anti-cancer activity. Therefore, synthetic methods providing access to pyrazolo [4, 3-c] quinolin-3-ones are immensely valuable. Here, we are reporting a simple but efficient route for the synthesis of novel 8-morpholino-2-aryl - 2, 5-dihydro-3H-pyrazolo [4, 3-c] quinolin-3-one derivatives. Further, molecular docking studies of synthesized compounds with human PDE5A protein showed that all the compounds exhibited good docking score in comparison with known inhibitors. In addition, all the synthesized molecules were evaluated against HCT116 cell lines for their antitumor activity. Among all the synthesized compounds, compound 5a, 5d, and 6e showed better cytotoxicity. Thus, these derivatives can be studied as potential inhibitors of PDE5A.

The PDE9A inhibitor PF04447943 improves coronary arteriole vasodilation and left ventricular diastolic dysfunction in HFpEF

Coronary microvascular dysfunction develops in patients with heart failure with preserved ejection fraction (HFpEF, also known as diastolic heart failure). Phosphodiesterase 9A (PDE9A) was shown to be upregulated in the hypertrophic myocardium in HFpEF patients. The hypothesis tested was that PDE9A inhibition improves coronary arteriole vasodilation and left ventricle (LV) diastolic function in HFpEF. The obese ZSF1 rat, a model of human HFpEF, was employed in which it was found that LV diastolic dysfunction develops by 20 weeks of age. 18‐week old male obese ZSF‐1 rats were treated with PDE9A inhibitor, PF04447943 (3 mg/kg) or vehicle by daily oral gavage for 2 weeks and LV diastolic function was assessed by transthoracic echocardiography (E/A ratio and deceleration time) and vasodilation was examined in isolated and pressurized (70 mmHg) small coronary arteries (150–200 μm in diameter) using videomicroscopy. Results showed that LV relaxation and coronary artery dilations to acetylcholine (ACh) and also to the direct nitric oxide donor, sodium nitroprusside (SNP) were significantly reduced in the 20‐week old vehicle treated obese ZSF‐1 rats, when compared to lean controls. In the PDE9A inhibitor, PF04447943 treated obese ZSF1 rats both LV diastolic function and coronary artery dilations to ACh and SNP were improved significantly. Further results revealed that ex vivo exposure of coronary arteries to PF04447943 (18 nmol/l for 30 minutes) also augmented vasodilation in response to ACh and SNP in the obese ZSF‐1 rats. It was concluded that PDE9A inhibition improves LV diastolic function and increases agonist‐induced coronary arteriole dilation in an animal model of HFpEF.Support or Funding InformationAmerican Heart Association 17GRNT33680171, NIH F31 HL142183‐01 and NIH R01AG054651This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Benzothiophene derivatives as phosphodiesterase 10A (PDE10A) inhibitors: Hit-to-lead studies

A novel series of benzothiophene derivatives was discovered as phosphodiesterase 10A (PDE10A) inhibitors. Structure-activity relationship studies on high-throughput screening hit compound 1 led to the identification of 7-acetyl-3-methyl-N-(quinolin-2-yl)-1-benzothiophene-2-carboxamide (16), with potent inhibitory activity (PDE10A IC50 = 7.6 nM) and selectivity (>1300-fold selectivity over the other tested phosphodiesterases). In addition, a novel methyl-induced conformational alteration of the benzothiophene-2-carboxamide derivatives is reported.

Scalable Process Design for a PDE10A Inhibitor Consisting of Pyrazolopyrimidine and Quinoxaline as Key Units

In this study, research and development for the synthetic process of a PDE10A inhibitor are described; in particular, an efficient regioselective construction of the quinoxaline unit, a cost-effective pyrazolo[1,5-a]pyrimidine formation, and a cost-saving approach in a nucleophilic aromatic substitution (SNAr) reaction by introducing oxazolidinone as an electron-withdrawing group to a chloropyrazolo[1,5-a]pyrimidine core are key points. The newly developed process has been successfully scaled up to 40 kg. Furthermore, a one-pot tandem reaction from aminopyrazole to dichloropyrazolo[1,5-a]pyrimidine by activating malonic acid with POCl3 was discovered. The finding contributed to avoiding isolation of the hygroscopic pyrazolo[1,5-a]pyrimidin-5(4H)-one intermediate, which caused complicated filtration and drying processes observed in the first scale-up campaign.

Reduced phosphodiesterase-2 activity in the amygdala results in anxiolytic-like effects on behavior in mice.

Phosphodiesterase-2 (PDE2) is a cyclic nucleotide phosphodiesterase and is highly expressed in the amygdala, which suggests its important role in anxiety-like behavior. The present study examined whether reduced PDE2A expression in the central nucleus of the amygdala (CeA) produces anxiolytic-like effects in mice. PDE2A knockdown in amygdaloid (AR5) cells or the CeA was established using a lentiviral vector-based siRNA system. The anxiety-like behaviors were detected by the elevated plus maze (EPM) and hole-board tests in mice. The related proteins involved in cAMP/cGMP-dependent signaling, such as specific marker VASPser239, CREBser133 and BDNF were detected by immunoblot analysis. PDE2A inhibition in AR-5 cells resulted in increases in cAMP/cGMP-related pVASPser239 and pCREBser133. Behavioral tests showed that PDE2A knockdown in the CeA induced anxiolytic-like effects as evidenced by the increases in percentages of open-arm entries and time spent in the open arms in the EPM test, and the increases in head dips and time spent in head dipping in the hole-board test. However, these anxiolytic-like effects were antagonized by pre-treatment of soluble guanylyl cyclase inhibitor ODQ or adenylate cyclase inhibitor SQ. Furthermore, PDE2A knockdown significantly increased pVASPSer239, pCREBSer133 and decreased BDNF expression in the amygdala. Pre-intra-CeA of ODQ or SQ reversed or partially prevented the effects of PDE2A knockdown on these proteins. The results suggest that PDE2A plays a crucial role in the regulation of anxiety by the cGMP/cAMP-dependent pVASP-pCREB-BDNF signaling pathway.

Practical Preparation of a 1,3,5-Trisubstituted Pyridazin-4(1H)-one Using Selective C1 Unit Insertion and Cyclization

A novel and practical preparation of the selective phosphodiesterase 10A (PDE10A) inhibitor 1 having the core moiety of a 1,3,5-trisubstituted pyridazin-4(1H)-one has been achieved. The facile preparation of 1 in 42% overall yield involves the following key features: (1) the finding that filling the headspace of the reaction vessel with Ar gas and controlling the flow rate of the gas were found to be important to complete the substitution of an aryl iodide with pyrazole; (2) synthesis of a 3-acetyl-5-methoxy-substituted pyridazin-4(1H)-one via regioselective dimethylaminomethylenation of a diazo compound and simultaneous cyclization; and (3) regioselective ring formation of a 1,5-disubstituted pyrazole through reaction of a dimethylaminomethylene group with phenylhydrazine. In addition, an alternative synthesis of 1 via selective alkylation of 1-phenylpyrazole has been discovered.

In vitro phosphodiesterase 10A (PDE10A) binding in whole hemisphere human brain using the PET radioligand [18F]MNI-659

Highly specific and sensitive biomarkers for pathologies related to dysfunctions in the basal ganglia circuit are of great value to assess therapeutic efficacy not only clinically to establish an early diagnosis, but also in terms of monitoring the efficacy of therapeutic interventions and decelerated neurodegeneration. The phosphodiesterase 10A (PDE10A) enzyme plays a central role in striatal signaling and is implicated in several neuropsychiatric disorders involving striatal pathology, such as Huntingtońs disease (HD) and schizophrenia. Inhibition of PDE10A activates the neurons in the striatum and consequently leads to alteration of behavioral aspects modulated by the striatal circuit. [18F]MNI-659, (2-(2-(3-(4-(2-[18F]fluoroethoxy)phenyl)-7-methyl-4-oxo-3,4-dihydroquinazolin-2-yl)ethyl)-4-isopropoxyisoindoline-1,3-dione), is a newly developed PET radioligand that shows a high binding to PDE10A in the human brain in vivo. In the present study, we examined the in vitro binding of [18F]MNI-659 in human postmortem brain to gain a better understanding of the presence, density, disease-related alterations and therapy related to changes in PDE10A expression. The results show high specific binding of [18F]MNI-659 in the caudate nucleus, putamen and the hippocampal formation. Low specific [18F]MNI-659 binding was detected in nucleus accumbens in comparison to the caudate nucleus and putamen. In vitro binding studies with [18F]MNI-659 will facilitate in elucidating better understanding of the role of PDE10A activity in health and disease that may lead to new diagnostic opportunities in HD.

Highlight of New Phosphodiesterase 10A Inhibitors Using Molecular Docking

Phosphodiesterase 10A (PDE 10A) is an effective therapeutic approach for treatments of Schizophrenia (SCZ). In order to identify in silico new potent PDE 10A inhibitors, molecular docking approach was used. In this context, the compound S235 was predicted to exhibit a high potential PDE 10A inhibitory activity among 369 compounds tested. The predicted binding energy of this compound was improved from -10.28 to -13.80 Kcal/mol by structural replacements of its chemical grouping. Finally, the proposed compound was predicted to have good ADMET properties.

CPL-500-036-02 – novel and highly bioavailable PDE10A inhibitor activates cyclic nucleotides depending signaling in rat striatum

CPL-500-036-02 – novel and highly bioavailable PDE10A inhibitor activates cyclic nucleotides depending signaling in rat striatum

Surface Binding Energy Landscapes Affect Phosphodiesterase Isoform-Specific Inhibitor Selectivity

As human phosphodiesterase (PDE) proteins are attractive drug targets, a large number of selective PDE inhibitors have been developed. However, since the catalytic sites of PDE isoforms are conserved in sequence and structure, it remains unclear how these inhibitors discriminate PDE isoforms in a selective manner. Here we perform long-time scale molecular dynamics (MD) simulations to investigate the spontaneous association processes of a highly selective PDE2A inhibitor (BAY60–7550) with the catalytic pockets of six PDE isoforms. We found that the free-energy landscapes of PDE:BAY60–7550 interactions on the PDE surfaces are very different between various PDE isoforms; and the free-energy landscape of PDE2A forms a favorable low-energy pathway that not only drives BAY60–7550 toward the target binding site, but also guides BAY60–7750 to adopt its native binding conformation known from crystal structure. Thus, this study reveals that the inhibitor interactions with the PDE surface residues play an important role in its high selectivity for PDE2A, and thereby provides new fundamental insights into the PDE isoform-specific inhibitor selectivity.

Novel, potent, selective, and brain penetrant phosphodiesterase 10A inhibitors

Herein we report the discovery of a novel series of phosphodiesterase 10A inhibitors. Optimization of a HTS hit (17) resulted in potent, selective, and brain penetrant 23 and 26; both exhibited much lower clearance in vivo and decreased volume of distribution (rat PK) and have thus the potential to inhibit the PDE10A target in vivo at a lower efficacious dose than the reference compound WEB-3.

Advances in Discovery of PDE10A Inhibitors for CNS-Related Disorders. Part 1: Overview of the Chemical and Biological Research.

Phosphodiesterase 10A (PDE10A) is a double substrate enzyme that hydrolyzes second messenger molecules such as cyclic-3',5'-adenosine monophosphate (cAMP) and cyclic-3',5'-guanosine monophosphate (cGMP). Through this process, PDE10A controls intracellular signaling pathways in the mammalian brain and peripheral tissues. Pharmacological, biochemical, and anatomical data suggest that disorders in the second messenger system mediated by PDE10A may contribute to impairments in the central nervous system (CNS) function, including cognitive deficits as well as disturbances of behavior, emotion processing, and movement. This review provides a detailed description of PDE10A and the recent advances in the design of selective PDE10A inhibitors. The results of preclinical studies regarding the potential utility of PDE10A inhibitors for the treatment of CNS-related disorders, such as schizophrenia as well as Huntington's and Parkinson's diseases are also summarized.

Prokaryotic Expression, Purification and Identification of Human PDE9A Protein

Cerebral aggregation of beta amyloid plaques (Aβ) and neurofibrillary tangles is responsible for the onset of Alzheimer’s disease (AD), and PDE9A inhibition rescues Aβ-induced deficits in synaptic plasticity and cognition. This study was aimed to express active PDE9A protein for subsequent inhibitor screening. The PDE9A gene was cloned from human cDNA by real-time polymerase chain reaction, and then the gene sequence and its amino acid sequence were analyzed on Lasergene. An inducible expression vector was constructed by enzyme digestion-seamless cloning and transformed into Escherichia coli BL21 (DE3) for PDE9A expression with isopropyl β-D-1-thiogalactopyranoside (IPTG) as an inducer. The recombinant protein was purified by Ni-NTA affinity chromatography and its activity was determined by a phosphodiesterase assay kit. It was found the open reading frame of PED9A was 1035 bp long, the deduced protein was composed of 345 amino acids, and its predicted isoelectric point was about 4.84. The E. coli vector ST6-PDE9A successfully expressed the recombinant PDE9A protein in the supernatant of bacterial lysate. The optimal culture conditions were that the bacterium ST6-PDE9A was grown first in a lysogeny broth at 37 ºC to an OD600 of 0.6-0.8 and then at 16 ºC for 40 h with the addition of 1 M IPTG. Activity test showed PDE9A significantly hydrolyzed the substrate cyclic guanosine monophosphate. In conclusion, we constructed a prokaryotic expression vector and expressed active proteins, laying a solid foundation for screening PDE9 inhibitors.

Partial loss of psychiatric risk gene Mir137 in mice causes repetitive behavior and impairs sociability and learning via increased Pde10a.

Genetic analyses have linked MicroRNA-137 (MIR137) to neuropsychiatric disorders, including schizophrenia and autism spectrum disorder (ASD). MiR-137 plays important roles in neurogenesis and neuronal maturation, but the impact of miR-137 loss of function in vivo remains unclear. Here we show the complete loss of miR-137 in the mouse germline (gKO) or nervous system (cKO) leads to postnatal lethality, while heterozygous gKO and cKO mice remain viable. Partial loss of miR-137 in heterozygous cKO mice results in dysregulated synaptic plasticity, repetitive behavior, and impaired learning and social behavior. Transcriptomic and proteomic analyses revealed that the miR-137 mRNA target, Phosphodiesterase 10a (Pde10a), is elevated in heterozygous KO mice. Treatment with the PDE10A inhibitor papaverine or knockdown of Pde10a ameliorates the deficits observed in the heterozygous cKO mice. Collectively, our results suggest that MIR137 plays essential roles in postnatal neurodevelopment, and that dysregulation of miR-137 potentially contributes to neuropsychiatric disorders in humans.

Phosphodiesterase 10 Inhibitors - Novel Perspectives for Psychiatric and Neurodegenerative Drug Discovery.

The phosphodiesterase 10 (PDE10) family, identified in 1999, is mainly expressed in the brain, particularly in the striatum, within the medium spiny neurons, nucleus accumbens, and olfactory tubercle. Inhibitors of PDE10 (PDE10-Is) are a conceptually rational subject for medicinal chemistry with potential use in the treatment of psychiatric and neurodegenerative diseases. This review is based on peer-reviewed published articles, and summarizes the cellular and molecular biology of PDE10 as a rational target for psychiatric and neurodegenerative drug discovery. Here, we present the classification of PDE10-Is from a medicinal chemistry point of view across a wide range of different, drug-like chemotypes starting from theophylline and caffeine analogs, papaverine and dimethoxy catechol type PDE10-Is, TP-10, MP-10, MP-10/papaverine/quinazoline series inhibitors, and ending with the newest inhibitors obtained from fragment-based lead discovery (FBLD). The authors have collated recent research on inhibition of PDE10A as a promising therapeutic strategy for psychiatric and neurodegenerative diseases, based on its efficacy in animal models of schizophrenia, Parkinson's, Huntington's, and Alzheimer's diseases. This review also presents pharmacological data on PDE10-Is as possible therapeutics for the treatment of cognitive deficits, obesity and depression. Moreover, it summarizes the current strategies for PDE10-Is drug discovery based on the results of clinical trials. The authors also present the latest studies on crystal structures of PDE10 complexes with novel inhibitors.