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One third of epilepsy patients are resistant to treatment with current anti-seizure medications. The ketogenic diet is used to treat some forms of refractory epilepsy, but the mechanism of its action has not yet been elucidated. In this study, we aimed to investigate whether the hydroxycarboxylic acid receptor 2 (HCA2), a known immunomodulatory receptor, plays a role in mediating the protective effect of this diet. We demonstrate for the first time that selective agonists at this receptor can directly reduce seizures in animal models. Agonists also reduce network activity in rodent and human brain slices. Ketogenic diet is known to increase circulating levels of endogenous HCA2 agonists, and we show that the effect of ketogenic diet in reducing seizures in the 6 Hz seizure model is negated in HCA2-deficient mice. Our data support the potential of HCA2 as a target for the treatment of epilepsy and potentially for neurodegenerative diseases., (© 2024 GSK. Pharmacology Research & Perspectives published by British Pharmacological Society and American Society for Pharmacology and Experimental Therapeutics and John Wiley & Sons Ltd.)

The metabolism and disposition of zamicastat, a reversible dopamine β-hydroxylase (DβH) inhibitor, developed for treatment of Pulmonary Arterial Hypertension (PAH), were investigated in rats after oral and intravenous administration of [ 14 C]-zamicastat.Zamicastat was rapidly absorbed and widely distributed to peripheral tissues, with total radioactivity almost completely recovered 168 h post-dose. Its main route of excretion was via faeces, whilst urine and expired air had minor roles.Maximum plasma concentration of zamicastat-related radioactivity occurred in the first hours, remaining quantifiable up to 144 h. The unchanged zamicastat plasma peak was 2 h post-dose and declined to low levels over 24 h.Zamicastat metabolism occurs largely during the first 8 h with only one metabolite identified in the latest time-point (96 h), the isothiocyanic acid/thiocyanic acid (tautomeric forms). Zamicastat metabolic pathway involved multiple reactions comprising desulphurisation, oxidative desulphurisation, N-debenzylation followed by further oxidation or N-acetylation, and the unexpected multistep metabolic pathway leading to isothiocyanic acid/thiocyanic acid.

Background: The wearing-off phenomenon is a key driver of medication change for patients with Parkinson's disease (PD) treated with levodopa. Common first-line options include increasing the levodopa dose or adding a catechol-O-methyltransferase (COMT) inhibitor, but there are no trials comparing the efficacy of these approaches. We evaluated the effectiveness of adjunct opicapone versus an additional 100 mg levodopa dose in PD patients with early wearing-off using pooled data from 2 randomized studies., Methods: The ADOPTION study program included two similarly designed 4-week, open-label studies conducted in South Korea (NCT04821687) and Europe (NCT04990284). Patients with PD, treated with 3-4 daily doses of levodopa therapy and with signs of early wearing-off were randomized (1:1) to adjunct opicapone 50 mg or an additional dose of levodopa 100 mg. Patient-level data from the two studies were pooled., Results: The adjusted mean [SE] change from baseline to week 4 in absolute OFF time (key endpoint) was - 62.8 min [8.8] in the opicapone group and - 33.8 min [9.0] in the levodopa 100 mg group, the difference significantly favoring opicapone (- 29.0 [- 53.8, - 4.2] min, p = 0.02). Significant differences in the Movement Disorder Society-Unified Parkinson's Disease Rating Scale Part III subscore (- 4.1 with opicapone vs - 2.5 with levodopa 100 mg), also favored opicapone (- 1.7 [- 3.3, - 0.04], p < 0.05). Dyskinesia was the most frequently reported adverse event (opicapone 7.2% vs. levodopa 100 mg 4.2%)., Conclusions: In these short-term trials, introducing adjunct opicapone was more effective at reducing OFF time than adding another 100 mg levodopa dose in PD patients with early signs of wearing-off., (© 2024. The Author(s).)

A post hoc analysis of data from Asian patients included in the study BIA-2093-304 was conducted to evaluate the long-term safety/tolerability and efficacy of adjunctive eslicarbazepine acetate (ESL) in adult Asian patients with refractory focal seizures. Part I was a randomized controlled trial, in which patients received ESL (800 or 1200 mg once daily [QD]) or placebo, assessed over a 12-week maintenance period. Patients completing Part I could enter two open-label extension periods (Part II, 1 year; Part III, ≥2 years), during which all received ESL (400-1600 mg QD). Safety/tolerability was assessed by evaluating treatment-emergent adverse events (TEAEs). Efficacy assessments included responder and seizure freedom rates. The safety population included 125, 92, and 23 Asian patients in Parts I, II, and III, respectively. Incidence of ESL-related TEAEs was 61.3%, 45.7%, and 17.4% during Parts I, II, and III, respectively. ESL-related TEAEs (most commonly, dizziness, somnolence, and headache) were consistent with ESL's known safety profile. During Part I, responder rates were higher with ESL 800 (41.7%) and 1200 mg QD (44.4%) versus placebo (32.6%), although not statistically significant. Seizure freedom rates with ESL 800 (5.5%) and 1200 mg QD (11.1%) were also higher versus placebo (0%) (p < 0.05 for ESL 1200 mg QD versus placebo). At the end of Part II, responder and seizure freedom rates were 60.3% and 14.7%, respectively. In summary, adult Asian patients with refractory focal seizures were responsive to treatment with ESL as adjunctive therapy and generally showed treatment tolerance well for up to 3 years. No new/unexpected safety findings were observed., (© 2024 The Authors. Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Lead Generation represents a critical drug discovery phase where chemical starting points and their respective mechanism of action, quality, and potential liabilities are largely predefined. Recent advances such as DNA-encoded libraries or fragment-, chemical biology-, and virtual screening-based approaches are today as common as traditional High Throughput Screening. Innovations in characterizing lead quality have allowed more informed decision-making by discovery teams. The key challenge today is to individually tailor the right mix of methods for each project to facilitate data integration with the purpose of creating multiple high-quality lead series, ultimately translating to reduced chemistry-related pipeline attrition., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Neuronal voltage-gated potassium channels, K V 7s, are the molecular mediators of the M current and regulate membrane excitability in the central and peripheral neuronal systems. Herein, we report novel small molecule K V 7 openers that demonstrate anti-seizure activities in electroshock and pentylenetetrazol-induced seizure models without influencing Rotarod readouts in mice. The anti-seizure activity was determined to be proportional to the unbound concentration in the brain. K V 7 channels are also expressed in the bladder smooth muscle (detrusor) and activation of these channels may cause localized undesired effects. Therefore, the impact of individual K V 7 isoforms was investigated in human detrusor tissue using a panel of K V 7 openers with distinct activity profiles among K V 7 isoforms. KCNQ4 and KCNQ5 mRNA were highly expressed in detrusor tissue, yet a compound that has significantly reduced activity on homomeric K V 7.4 did not reduce detrusor contraction. This may suggest that the homomeric K V 7.4 channel plays a less significant role in bladder contraction and further investigation is needed., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

BACE1 is responsible for the first step in APP proteolysis, leading to toxic Aβ production, and has been indicated to play a key role in the pathogenesis of Alzheimer's disease. The related isoform BACE2 is thought to be involved in processing of the pigment cell-specific melanocyte protein. To avoid potential effects on pigmentation, we investigated the feasibility for developing isoform-selective BACE1 inhibitors. Cocrystal structures of 47 compounds were analyzed and clustered according to their selectivity profiles. Selective BACE1 inhibitors were found to exhibit two distinct conformational features proximal to the flap and the S3 subpocket. Several new molecules were designed and tested to make use of this observation. The combination of a pyrimidinyl C-ring and a methylcyclohexyl element resulted in lead molecule 28, which exhibited ∼50-fold selectivity. Compared to a nonselective BACE1/2 inhibitor, 28 showed significantly less inhibition of PMEL processing in human melanocytes, indicating good functional selectivity of this inhibitor class.

Recently, the discovery of the aminoisoindoles as potent and selective inhibitors of β-secretase was reported, including the close structural analogs compound (S)-1-pyridin-4-yl-4-fluoro-1-(3-(pyrimidin-5-yl)phenyl)-1H-isoindol-3-amine [(S)-25] and (S)-1-(2-(difluoromethyl)pyridin-4-yl)-4-fluoro-1-(3-(pyrimidin-5-yl)phenyl)-1H-isoindol-3-amine hemifumarate (AZD3839), the latter being recently progressed to the clinic. The biotransformation of (S)-25 was investigated in vitro and in vivo in rat, rabbit, and human and compared with AZD3839 to further understand the metabolic fate of these compounds. In vitro, CYP3A4 was the major responsible enzyme and metabolized both compounds to a large extent in the commonly shared pyridine and pyrimidine rings. The main proposed metabolic pathways in various in vitro systems were N-oxidation of the pyridine and/or pyrimidine ring and conversion to 4-pyrimidone and pyrimidine-2,4-dione. Both compounds were extensively metabolized, and more than 90% was excreted in feces after intravenous administration of radiolabeled compound to the rat. Here, the main pathways were N-oxidation of the pyridine and/or pyrimidine ring and a ring contraction of the pyrimidine ring into an imidazole ring. Ring-contracted metabolites accounted for 25% of the total metabolism in the rat for (S)-25, whereas the contribution was much smaller for AZD3839. This metabolic pathway was not foreseen on the basis of the obtained in vitro data. In conclusion, we discovered an unusual metabolic pathway of aryl-pyrimidine-containing compounds by a ring-opening reaction followed by elimination of a carbon atom and a ring closure to form an imidazole ring.

The evaluation of a series of aminoisoindoles as β-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitors and the discovery of a clinical candidate drug for Alzheimer's disease, (S)-32 (AZD3839), are described. The improvement in permeability properties by the introduction of fluorine adjacent to the amidine moiety, resulting in in vivo brain reduction of Aβ40, is discussed. Due to the basic nature of these compounds, they displayed affinity for the human ether-a-go-go related gene (hERG) ion channel. Different ways to reduce hERG inhibition and increase hERG margins for this series are described, culminating in (S)-16 and (R)-41 showing large in vitro margins with BACE1 cell IC(50) values of 8.6 and 0.16 nM, respectively, and hERG IC(50) values of 16 and 2.8 μM, respectively. Several compounds were advanced into pharmacodynamic studies and demonstrated significant reduction of β-amyloid peptides in mouse brain following oral dosing.

The synthesis and pharmacological activity of a new series of 1-arylpyrazoles as potent σ(1) receptor (σ(1)R) antagonists are reported. The new compounds were evaluated in vitro in human σ(1)R and guinea pig σ(2) receptor (σ(2)R) binding assays. The nature of the pyrazole substituents was crucial for activity, and a basic amine was shown to be necessary, in accordance with known receptor pharmacophores. A wide variety of amines and spacer lengths between the amino and pyrazole groups were tolerated, but only the ethylenoxy spacer and small cyclic amines provided compounds with sufficient selectivity for σ(1)R vs σ(2)R. The most selective compounds were further profiled, and compound 28, 4-{2-[5-methyl-1-(naphthalen-2-yl)-1H-pyrazol-3-yloxy]ethyl}morpholine (S1RA, E-52862), which showed high activity in the mouse capsaicin model of neurogenic pain, emerged as the most interesting candidate. In addition, compound 28 exerted dose-dependent antinociceptive effects in several neuropathic pain models. This, together with its good physicochemical, safety, and ADME properties, led compound 28 to be selected as clinical candidate.

Two series of σ(1) ligands with a spiro[[2]benzopyran-1,3'-pyrrolidine] (3) and a spiro[[2]benzofuran-1,3'-pyrrolidine] (4) framework were synthesized and pharmacologically evaluated. Several reaction steps were considerably improved by microwave irradiation. The σ(1) affinity of the spirocyclic ligands correlates nicely with the benzene-N-distance, i.e. 2 < 3 < 4 < 1. The σ(1) affinity of both compound classes could be increased with large N-substituents (e.g. 2-phenylethyl, octyl). Nevertheless the benzyl derivative 4a represents the most promising σ(1) ligand (K(i) = 25 nM) due to its high selectivity against the σ(2) subtype (>40-fold), the NMDA receptor and 5-HT(6) and 5-HT(7) receptors. Moreover, 4a did not inhibit the hERG channel in the heart., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

On the basis of the 6',7'-dihydrospiro[piperidine-4,4'-thieno[3,2-c]pyran] framework, a series of more than 30 σ ligands with versatile substituents in 1-, 2'-, and 6'-position has been synthesized and pharmacologically evaluated in order to find novel structure-affinity relationships. It was found that a cyclohexylmethyl residue at the piperidine N-atom instead of a benzyl moiety led to increased σ(2) affinity and therefore to decreased σ(1)/σ(2) selectivity. Small substituents (e.g., OH, OCH(3), CN, CH(2)OH) in 6'-position adjacent to the O-atom were well tolerated by the σ(1) receptor. Removal of the substituent in 6'-position resulted in very potent but unselective σ ligands (13). A broad range of substituents with various lipophilic and H-bond forming properties was introduced in 2'-position adjacent to the S-atom without loss of σ(1) affinity. However, very polar and basic substituents in both 2'- and 6'-position decreased the σ(1) affinity considerably. It is postulated that the electron density of the thiophene moiety has a big impact on the σ(1) affinity.

The evaluation of a series of bicyclic aminoimidazoles as potent BACE-1 inhibitors is described. The crystal structures of compounds 14 and 23 in complex with BACE-1 reveal hydrogen bond interactions with the protein important for achieving potent inhibition. The optimization of permeability and efflux properties of the compounds is discussed as well as the importance of these properties for attaining in vivo brain efficacy. Compound (R)-25 was selected for evaluation in vivo in wild type mice and 1.5h after oral co-administration of 300μmol/kg (R)-25 and efflux inhibitor GF120918 the brain Aβ40 level was reduced by 17% and the plasma Aβ40 level by 76%., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The novel class of spirocyclic σ(1) ligands 3 (6',7'-dihydro-1'H-spiro[piperidine-4,4'-pyrano[4,3-c]pyrazoles]) was designed by the combination of the potent σ(1) ligands 1 and 2 in one molecule. Thorough structure affinity relationships were derived by the variation of the substituents in position 1', 1, and 6'. Whereas the small electron rich methylpyrazole heterocycle was less tolerated by the σ(1) receptor protein, the introduction of a phenyl substituent instead of the methyl group led to ligands with a high σ(1) affinity. It is postulated that the additional phenyl substituent occupies a previously unrecognized hydrophobic region of the σ(1) receptor resulting in additional lipophilic interactions. The spirocyclic pyranopyrazoles are very selective against the σ(2) subtype, the PCP binding site of the NMDA receptor, and further targets. Despite high σ(1) affinity, the cyclohexylmethyl derivative 17i (K(i) (σ(1)) = 0.55 nM) and the isopentenyl derivative 17p (K(i) (σ(1)) = 1.6 nM) showed only low antiallodynic activity in the capsaicin assay.

Based on the pharmacophore model of Glennon the conformationally restricted σ(1) receptor ligand 2 with a 1,3-dioxane moiety has been designed and synthesized. The three step synthesis (transacetalization with pentane-1,3,5-triol, tosylation, and nucleophilic substitution with benzylamine) provided diastereoselectively the cis-configured 1,3-dioxane 2 in good yields. The 1,3-dioxane 2 represents a potent σ(1) receptor ligand (K(i) = 19 nM) with moderate selectivity over the σ(2) subtype (K(i) = 92 nM) and excellent selectivity against more than 60 other targets. Additionally the hERG K(+) channel is not affected by 2. In the capsaicin assay 2 showed extraordinarily high analgesic activity with more than 70% analgesia at the very low dose of 0.25 mg/kg body weight, which indicates σ(1) antagonistic activity. Since 2 does only interact with σ(1) receptors, the in-vivo antiallodynic activity of 2 must be attributed to the σ(1) antagonistic activity., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The symmetrically connected spiro[[2]benzopyran-1,4'-piperidines] 1 are highly potent and selective sigma(1) receptor ligands. Changing the position of the spirocyclic nitrogen atom led to the unsymmetrically connected spiro[[2]benzopyran-1,3'-piperidines] 2 with a reduced distance between the aromatic system and the basic nitrogen atom. The synthesis of 2 was performed by halogen-metal exchange at the aryl bromide 3 followed by addition to the piperidone 5 and intramolecular transacetalization. The yield of 2a was considerably improved by transmetallation of the aryllithium intermediate 4a with CeCl(3) (4c). The cis and trans diastereomers cis-2 and trans-2 were separated and characterized by nuclear Overhauser effect. After removal of the benzyl group, the secondary amine 2b was alkylated with various alkyl and arylalkyl halides. The sigma(1) and sigma(2) receptor affinity of the spirocyclic piperidines 2 were determined with receptor binding studies. Compared with the spirocyclic piperidines 1, the unsymmetrically connected piperidines 2 show remarkably reduced sigma(1) receptor affinities, whereas the selectivity over sigma(2) and NMDA receptors was retained. A stereoselective interaction of the sigma(1) receptor protein with the cis- or trans-configured spirocyclic compounds 2 was not observed. It was shown that alkyl residues at the N-atom can replace the lipophilic N-arylalkyl groups and interact with the primary hydrophobic binding site of the sigma(1) receptor protein.