ABSTRACT
BACKGROUND: There is a need for new and effective oral asthma therapies. Dexpramipexole, an oral eosinophil-lowering drug, has not previously been studied in asthma. OBJECTIVE: We sought to evaluate the safety and efficacy of dexpramipexole in lowering blood and airway eosinophilia in subjects with eosinophilic asthma. METHODS: We performed a randomized, double-blind, placebo-controlled proof-of-concept trial in adults with inadequately controlled moderate to severe asthma and blood absolute eosinophil count (AEC) greater than or equal to 300/µL. Subjects were randomly assigned (1:1:1:1) to dexpramipexole 37.5, 75, or 150 mg BID (twice-daily) or placebo. The primary end point was the relative change in AEC from baseline to week 12. Prebronchodilator FEV1 week-12 change from baseline was a key secondary end point. Nasal eosinophil peroxidase was an exploratory end point. RESULTS: A total of 103 subjects were randomly assigned to dexpramipexole 37.5 mg BID (N = 22), 75 mg BID (N = 26), 150 mg BID (N = 28), or placebo (N = 27). Dexpramipexole significantly reduced placebo-corrected AEC week-12 ratio to baseline, in both the 150-mg BID (ratio, 0.23; 95% CI, 0.12-0.43; P < .0001) and the 75-mg BID (ratio, 0.34; 95% CI, 0.18-0.65; P = .0014) dose groups, corresponding to 77% and 66% reductions, respectively. Dexpramipexole reduced the exploratory end point of nasal eosinophil peroxidase week-12 ratio to baseline in the 150-mg BID (median, 0.11; P = .020) and the 75-mg BID (median, 0.17; P = .021) groups. Placebo-corrected FEV1 increases were observed starting at week 4 (nonsignificant). Dexpramipexole displayed a favorable safety profile. CONCLUSIONS: Dexpramipexole demonstrated effective eosinophil lowering and was well tolerated. Additional larger clinical trials are needed to understand the clinical efficacy of dexpramipexole in asthma.
Subject(s)
Anti-Asthmatic Agents , Asthma , Pulmonary Eosinophilia , Adult , Humans , Pramipexole/pharmacology , Pramipexole/therapeutic use , Eosinophil Peroxidase , Asthma/drug therapy , Pulmonary Eosinophilia/drug therapy , Eosinophils , Treatment Outcome , Double-Blind Method , Anti-Asthmatic Agents/therapeutic useABSTRACT
OBJECTIVE: Chronic rhinosinusitis with nasal polyps (CRSwNP) and eosinophilia is a disease of the upper respiratory tract for which few therapies are available. Because the oral investigational drug dexpramipexole serendipitously decreased blood eosinophils in amyotrophic lateral sclerosis studies, we assessed its safety, eosinophil-lowering activity, and preliminary clinical efficacy in patients with CRSwNP and eosinophilia. METHODS: Sixteen subjects with CRSwNP, absolute eosinophil count (AEC) ≥ 0.300 × 109 /L, and polyp tissue eosinophils were evaluable for efficacy in a 6-month open-label, multi-center study of dexpramipexole 150 mg twice daily. The coprimary endpoints were change in AEC and change in total polyp score (TPS) from baseline to month 6, with additional clinical and histologic endpoints assessed. RESULTS: Thirteen of 16 subjects completed 6 months of dexpramipexole treatment. Geometric mean baseline AEC was 0.525 ± 0.465 eosinophils × 109 /L and decreased to 0.031 ± 0.019 after 6 months of dexpramipexole treatment, a 94% reduction (P < 0.001). Ten of 16 subjects had eosinophil counts reduced to ≤ 0.020 × 109 /L at month 6. In 12 subjects with nasal polyp biopsies at baseline and month 6, tissue eosinophils were reduced from a mean of 168 ± 134 to 5 ± 2 per high-power field (HPF) (P = 0.001), a 97% reduction from baseline. There was no significant reduction in TPS or improvement in other clinical endpoints. Dexpramipexole was well tolerated, with no drug-related serious adverse events. CONCLUSION: Dexpramipexole treatment produced profound eosinophil-lowering in peripheral blood and nasal polyp tissue. Despite the near-elimination of polyp eosinophils, decreased TPS and nasal symptom improvement were not observed. LEVEL OF EVIDENCE: 2 Laryngoscope, 129:E61-E66, 2019.
Subject(s)
Antioxidants/therapeutic use , Eosinophilia/drug therapy , Eosinophils/drug effects , Nasal Polyps/drug therapy , Pramipexole/therapeutic use , Rhinitis/drug therapy , Sinusitis/drug therapy , Adult , Chronic Disease , Female , Humans , Male , Prospective Studies , Treatment OutcomeABSTRACT
Hypereosinophilic syndromes (HESs) are a heterogeneous group of disorders characterized by peripheral eosinophilia and eosinophil-related end organ damage. Whereas most patients respond to glucocorticoid (GC) therapy, high doses are often necessary, and side effects are common. Dexpramipexole (KNS-760704), an orally bioavailable synthetic aminobenzothiazole, showed an excellent safety profile and was coincidentally noted to significantly decrease absolute eosinophil counts (AECs) in a phase 3 trial for amyotrophic lateral sclerosis. This proof-of-concept study was designed to evaluate dexpramipexole (150 mg orally twice daily) as a GC-sparing agent in HESs. Dual primary end points were (1) the proportion of subjects with ≥50% decrease in the minimum effective GC dose (MED) to maintain AEC <1000/µL and control clinical symptoms, and (2) the MED after 12 weeks of dexpramipexole (MEDD) as a percentage of the MED at week 0. Out of 10 subjects, 40% (95% confidence interval [CI], 12%, 74%) achieved a ≥50% reduction in MED, and the MEDD/MED ratio was significantly <100% (median, 66%; 95% CI, 6%, 98%; P = .03). All adverse events were self-limited, and none led to drug discontinuation. Affected tissue biopsy samples in 2 subjects showed normalization of pathology and depletion of eosinophils on dexpramipexole. Bone marrow biopsy samples after 12 weeks of dexpramipexole showed selective absence of mature eosinophils in responders. Dexpramipexole appears promising as a GC-sparing agent without apparent toxicity in a subset of subjects with GC-responsive HESs. Although the exact mechanism of action is unknown, preliminary data suggest that dexpramipexole may affect eosinophil maturation in the bone marrow. This study was registered at www.clinicaltrials.gov as #NCT02101138.
Subject(s)
Antioxidants/administration & dosage , Eosinophils/drug effects , Hypereosinophilic Syndrome/drug therapy , Pramipexole/administration & dosage , Steroids , Administration, Oral , Adult , Aged , Female , Follow-Up Studies , Humans , Hypereosinophilic Syndrome/pathology , Male , Middle Aged , Prognosis , SafetyABSTRACT
Dexpramipexole, an orally bioavailable small molecule previously under clinical development in amyotrophic lateral sclerosis, was observed during routine safety hematology monitoring to demonstrate pronounced, dose- and time-dependent eosinophil-lowering effects, with minor reductions on other leukocyte counts. Analysis of hematology lab values across two double-blind, randomized placebo-controlled clinical trials at total daily doses ranging from 50mg to 300mg demonstrated that dexpramipexole consistently and markedly lowered peripheral blood eosinophils. This effect developed after 1month on treatment, required 3-4months to reach its maximum, remained constant throughout treatment, and partially recovered to baseline levels upon drug withdrawal. All doses tested were well tolerated. The overall adverse event rate was similar for dexpramipexole and placebo, and notably with no increase in infection-related adverse events associated with eosinophil-lowering effects. Given the reliance on and insufficiency of off-label chronic corticosteroid therapy for hypereosinophilic syndromes and other eosinophilic-associated diseases (EADs), a need exists for less toxic, more effective, targeted therapeutic alternatives. Further clinical studies are underway to assess the eosinophil-lowering effect of dexpramipexole in the peripheral blood and target tissues of EAD patients and whether such reductions, if observed, produce clinically important benefits.
Subject(s)
Benzothiazoles/pharmacology , Eosinophils/drug effects , Benzothiazoles/adverse effects , Benzothiazoles/therapeutic use , Dose-Response Relationship, Drug , Double-Blind Method , Eosinophilia/drug therapy , Eosinophils/cytology , Humans , Hypereosinophilic Syndrome/drug therapy , Infections/chemically induced , Leukocyte Count , PramipexoleABSTRACT
Inefficiency of oxidative phosphorylation can result from futile leak conductance through the inner mitochondrial membrane. Stress or injury may exacerbate this leak conductance, putting cells, and particularly neurons, at risk of dysfunction and even death when energy demand exceeds cellular energy production. Using a novel method, we have recently described an ion conductance consistent with mitochondrial permeability transition pore (mPTP) within the c-subunit of the ATP synthase. Excitotoxicity, reactive oxygen species-producing stimuli, or elevated mitochondrial matrix calcium opens the channel, which is inhibited by cyclosporine A and ATP/ADP. Here we show that ATP and the neuroprotective drug dexpramipexole (DEX) inhibited an ion conductance consistent with this c-subunit channel (mPTP) in brain-derived submitochondrial vesicles (SMVs) enriched for F1FO ATP synthase (complex V). Treatment of SMVs with urea denatured extramembrane components of complex V, eliminated DEX- but not ATP-mediated current inhibition, and reduced binding of [(14)C]DEX. Direct effects of DEX on the synthesis and hydrolysis of ATP by complex V suggest that interaction of the compound with its target results in functional conformational changes in the enzyme complex. [(14)C]DEX bound specifically to purified recombinant b and oligomycin sensitivity-conferring protein subunits of the mitochondrial F1FO ATP synthase. Previous data indicate that DEX increased the efficiency of energy production in cells, including neurons. Taken together, these studies suggest that modulation of a complex V-associated inner mitochondrial membrane current is metabolically important and may represent an avenue for the development of new therapeutics for neurodegenerative disorders.
Subject(s)
Benzothiazoles/pharmacology , Cyclosporine/pharmacology , Mitochondrial Membrane Transport Proteins/metabolism , Proton-Translocating ATPases/metabolism , Adenosine Triphosphate/metabolism , Adenosine Triphosphate/pharmacology , Brain/cytology , Brain/enzymology , Humans , Mitochondrial Membranes/drug effects , Mitochondrial Permeability Transition Pore , PramipexoleABSTRACT
Acrylamide (S)-6, a potent and efficacious KCNQ2 (Kv7.2) opener, demonstrated significant activity in two models of neuropathic pain and in the formalin test, suggesting that KCNQ2 openers may be useful in the treatment of neuropathic pain including diabetic neuropathy.
Subject(s)
Acrylamides/chemistry , Acrylamides/pharmacology , KCNQ2 Potassium Channel/metabolism , Neuralgia/drug therapy , Acrylamides/chemical synthesis , Animals , KCNQ2 Potassium Channel/chemistry , Male , Patch-Clamp Techniques , Rats , Rats, Sprague-DawleyABSTRACT
High throughput screening led to the identification of a novel series of quinolone α7 nicotinic acetylcholine receptor (nAChR) agonists. Optimization of an HTS hit (1) led to 4-phenyl-1-(quinuclidin-3-ylmethyl)quinolin-2(1H)-one, which was found to be potent and selective. Poor brain penetrance in this series was attributed to transporter-mediated efflux, which was in turn due to high pKa. A novel 4-fluoroquinuclidine significantly lowered the pKa of the quinuclidine moiety, reducing efflux as measured by a Caco-2 assay.
Subject(s)
Nicotinic Agonists/chemistry , Quinolones/chemistry , Receptors, Nicotinic/chemistry , Animals , Caco-2 Cells , Drug Evaluation, Preclinical , Humans , Kinetics , Nicotinic Agonists/chemical synthesis , Nicotinic Agonists/metabolism , Quinolones/chemical synthesis , Quinolones/metabolism , Rats , Receptors, Nicotinic/metabolism , Structure-Activity Relationship , alpha7 Nicotinic Acetylcholine ReceptorABSTRACT
Cellular stress or injury can result in mitochondrial dysfunction, which has been linked to many chronic neurological disorders including amyotrophic lateral sclerosis (ALS) and Parkinson's disease (PD). Stressed and dysfunctional mitochondria exhibit an increase in large conductance mitochondrial membrane currents and a decrease in bioenergetic efficiency. Inefficient energy production puts cells, and particularly neurons, at risk of death when energy demands exceed cellular energy production. Here we show that the candidate ALS drug dexpramipexole (DEX; KNS-760704; ((6R)-4,5,6,7-tetrahydro-N6-propyl-2,6-benzothiazole-diamine) and cyclosporine A (CSA) inhibited increases in ion conductance in whole rat brain-derived mitochondria induced by calcium or treatment with a proteasome inhibitor, although only CSA inhibited calcium-induced permeability transition in liver-derived mitochondria. In several cell lines, including cortical neurons in culture, DEX significantly decreased oxygen consumption while maintaining or increasing production of adenosine triphosphate (ATP). DEX also normalized the metabolic profile of injured cells and was protective against the cytotoxic effects of proteasome inhibition. These data indicate that DEX increases the efficiency of oxidative phosphorylation, possibly by inhibition of a CSA-sensitive mitochondrial conductance.
Subject(s)
Adrenergic beta-Antagonists/pharmacology , Energy Metabolism/drug effects , Membrane Potential, Mitochondrial/drug effects , Mitochondria/drug effects , Neurons/ultrastructure , Propranolol/pharmacology , Adenosine Triphosphate/metabolism , Analysis of Variance , Animals , Biophysical Phenomena/drug effects , Brain/cytology , Cell Survival/drug effects , Cells, Cultured , Cyclosporine/pharmacology , Dose-Response Relationship, Drug , Enzyme Inhibitors/pharmacology , Humans , Male , Mice , Mitochondrial Membranes/drug effects , Neuroblastoma/pathology , Neuroblastoma/ultrastructure , Oligopeptides/pharmacology , Oxygen Consumption/drug effects , Patch-Clamp Techniques , Rats , Rats, Sprague-DawleyABSTRACT
Compound 8a (BMS-191011), an opener of the cloned large-conductance, Ca2+-activated potassium (maxi-K) channel, demonstrated efficacy in in vivo stroke models, which led to its nomination as a candidate for clinical evaluation. Its maxi-K channel opening properties were consistent with its structural topology, being derived by combining elements from other known maxi-K openers. However, 8a suffered from poor aqueous solubility, which complicated elucidation of SAR during in vitro evaluation. The activity of 8a in in vivo stroke models and studies directed toward improving its solubility are reported herein. Enhanced solubility was achieved by appending heterocycles to the 8a scaffold, and a notable observation was made that inclusion of a simple amino group (anilines 8k and 8l) yielded excellent in vitro maxi-K ion channel opening activity and enhanced brain-to-plasma partitioning compared to the appended heterocycles.
Subject(s)
Large-Conductance Calcium-Activated Potassium Channels/physiology , Oxadiazoles/pharmacology , Animals , Brain/metabolism , Crystallography, X-Ray , Female , In Vitro Techniques , Ion Channel Gating , Molecular Structure , Oocytes/drug effects , Oocytes/physiology , Oxadiazoles/chemistry , Oxadiazoles/pharmacokinetics , Patch-Clamp Techniques , Plasma , Rats , Rats, Inbred SHR , Solubility , Stroke/drug therapy , Stroke/pathology , Structure-Activity Relationship , Xenopus laevisABSTRACT
The synthesis of a series of 3-beta-hydroxyethyl-4-arylquinolin-2-ones is described. These compounds contain hydrophilic and hydrophobic substituents ortho to the phenolic OH in the C ring of the quinolinone. Electrophysiological evaluation of the panel of compounds revealed that 11 and 16 with an unbranched ortho substituent retain activity as maxi-K ion channel openers. Members of this series of compounds can exist as stable atropisomers. Calculated estimates of the energy barrier for rotation around the aryl-aryl single bond in 3 is 31 kcal/mol. The atropisomers of (+/-)-3, (+/-)-4, and (+/-)-11 were separated by chiral HPLC and tested for their effect on maxi-K mediated outward current in hSlo injected X. laevis oocytes. The (-) isomer in each case was found to be more active than the corresponding (+) isomer, suggesting that the ion channel exhibits stereoselective activation. X-ray crystallographic structures of (+)-3 and (+)-11 were determined. Evaluation of the stability of (-)-3 at 80 degrees C in n-butanol indicated a 19.6% conversion to (+)-3 over 72 h. In human serum at 37 degrees C (-)-3 did not racemize over the course of the 30 h study.
Subject(s)
Large-Conductance Calcium-Activated Potassium Channels/drug effects , Quinolines/chemical synthesis , Animals , Crystallography, X-Ray , Female , Humans , In Vitro Techniques , Ion Channel Gating , Large-Conductance Calcium-Activated Potassium Channels/physiology , Molecular Structure , Oocytes/drug effects , Oocytes/physiology , Patch-Clamp Techniques , Quinolines/chemistry , Quinolines/pharmacology , Stereoisomerism , Thermodynamics , Xenopus laevisABSTRACT
The Slack (Sequence like a calcium-activated K channel) (Slo2.2) gene is abundantly expressed in the mammalian brain and encodes a sodium-activated K+ (KNa) channel. Although the specific roles of Slack channel subunits in neurons remain to be identified, they may play a role in the adaptation of firing rate and in protection against ischemic injury. In the present study, we have generated a stable cell line expressing the Slack channel, and have analyzed the pharmacological properties of these channels in these cells and in Xenopus oocytes. Two known blockers of KNa channels, bepridil and quinidine, inhibited Slack currents in a concentration-dependent manner and decreased channel activity in excised membrane patches. The inhibition by bepridil was potent, with an IC50 of 1.0 microM for inhibition of Slack currents in HEK cells. In contrast, bithionol was found to be a robust activator of Slack currents. When applied to the extracellular face of excised patches, bithionol rapidly induced a reversible increase in channel opening, suggesting that it acts on Slack channels relatively directly. These data establish an important early characterization of agents that modulate Slack channels, a process essential for the experimental manipulation of Slack currents in neurons.
Subject(s)
Potassium Channels, Calcium-Activated/physiology , Animals , Anti-Infective Agents, Local/pharmacology , Bepridil/pharmacology , Bithionol/pharmacology , Calcium Channel Blockers/pharmacology , Cell Line, Transformed , Dose-Response Relationship, Drug , Dose-Response Relationship, Radiation , Electric Stimulation/methods , Enzyme Activation/drug effects , Enzyme Inhibitors/pharmacology , Humans , Membrane Potentials/drug effects , Membrane Potentials/physiology , Membrane Potentials/radiation effects , Oocytes , Patch-Clamp Techniques/methods , Potassium Channels, Calcium-Activated/genetics , Quinidine/pharmacology , Transfection , XenopusABSTRACT
During the past five years, several members of the KCNQ potassium channel gene family have been identified with a high degree of CNS specificity. Within the KCNQ family, the combination of the KCNQ2/KCNQ3 proteins, and the KCNQ5/KCNQ3 arrangement has been identified as the molecular correlates of the different M-currents. Several lines of evidence are emerging demonstrating the importance of these channels in regulating neuronal excitability; for example, determination of the excitability threshold, firing properties, and responsiveness of neurons to synaptic inputs. Recent studies have shown that KCNQ openers have potential for the treatment of several CNS disorders characterized by neuronal hyperexcitability, such as migraine, epilepsy and neuropathic pain. This article reviews the recent developments of KCNQ potassium channel openers.
Subject(s)
Ion Channel Gating/physiology , Potassium Channels, Voltage-Gated/drug effects , Acrylamides/chemistry , Acrylamides/pharmacology , Aminopyridines/chemistry , Aminopyridines/pharmacology , Benzamides/chemistry , Benzamides/pharmacology , Carbamates/chemistry , Carbamates/pharmacology , Epilepsy/drug therapy , Humans , Indoles/chemistry , Indoles/pharmacology , Ion Channel Gating/genetics , KCNQ Potassium Channels , KCNQ1 Potassium Channel , Migraine Disorders/drug therapy , Oxindoles , Pain/drug therapy , Phenylenediamines/chemistry , Phenylenediamines/pharmacology , Potassium Channels, Voltage-Gated/genetics , Potassium Channels, Voltage-Gated/physiologyABSTRACT
Replacement of the morpholinyl moiety in (S,E)-N-[1-(3-morpholinophenyl)ethyl]-3-phenylacrylamide (1) with heteroaryl groups led to the identification of (S,E)-N-1-[3-(6-fluoropyridin-3-yl)phenyl]ethyl-3-(2-fluorophenyl)acrylamide (5) as a potent KCNQ2 potassium channel opener. Among this series of heteroaryl substituted acrylamides, (S,E)-N-1-[3-(1H-pyrazol-1-yl)phenyl]ethyl-3-(2-fluorophenyl)acrylamide (9) exhibits balanced potency and efficacy. The syntheses and the KCNQ2 opener activity of this series of acrylamides are described.
Subject(s)
Action Potentials/drug effects , Potassium Channels, Voltage-Gated/metabolism , Acrylamides/chemical synthesis , Acrylamides/pharmacology , Animals , Cell Line , Dose-Response Relationship, Drug , Humans , KCNQ2 Potassium Channel , Molecular StructureABSTRACT
A series of Maxi-K openers for the treatment of erectile dysfunction based on the 3-thio-quinolinone core is described. Significant levels of channel opening (up to 550% of control) are seen in transfected oocytes. Functional activity in rabbit corpus cavernosum tissue strips confirms the potential to effect therapy for ED, the effect being maximal for the 3-amino-2-hydroxy thiol side chain.
Subject(s)
Ion Channel Gating , Penile Erection/drug effects , Potassium Channels, Calcium-Activated/drug effects , Quinolines/chemical synthesis , Sulfides/chemical synthesis , Vasodilator Agents/chemical synthesis , Animals , Erectile Dysfunction/drug therapy , Humans , In Vitro Techniques , Large-Conductance Calcium-Activated Potassium Channels , Male , Muscle Relaxation/drug effects , Muscle Relaxation/physiology , Muscle, Smooth, Vascular/drug effects , Oocytes/drug effects , Oocytes/physiology , Patch-Clamp Techniques , Penile Erection/physiology , Penis/blood supply , Quinolines/chemistry , Quinolines/pharmacology , Rabbits , Structure-Activity Relationship , Sulfides/chemistry , Sulfides/pharmacology , Vasodilator Agents/chemistry , Vasodilator Agents/pharmacologyABSTRACT
Bioisosteric replacement studies led to the identification of N-(1-benzo[1,3]dioxol-5-yl-ethyl)-3-(2-chloro-phenyl)-acrylamide ((S)-3) as a highly potent KCNQ2 opener, and 3-(2,6-difluoro-phenyl)-N-[1-(2,3-dihydro-benzofuran-5-yl)-ethyl]-acrylamide ((S)-4), and N-[1-(2,3-dihydro-1H-indol-5-yl)-ethyl]-3-(2-fluoro-phenyl)-acrylamide ((S)-5) as highly efficacious KCNQ2 openers. In contrast, their respective R enantiomers showed significantly less or no appreciable KCNQ2 opener activity even at the highest concentration tested (10 microM). Because of its high potency and moderate efficacy as well as its convenient synthesis, (+/-)-3 was selected as a reference compound for analyzing efficacies of KCNQ openers in electrophysiology studies. Compounds (S)-4 and (S)-5 demonstrated significant activity in reducing neuronal hyperexcitability in rat hippocampal slices. The synthesis and the KCNQ2 opener activity of these acrylamides are described.
Subject(s)
Acrylamides/chemistry , Benzofurans/chemistry , Potassium Channels, Voltage-Gated/metabolism , Acrylamides/pharmacology , Animals , Benzofurans/pharmacology , Cell Line , Dose-Response Relationship, Drug , Hippocampus/drug effects , Hippocampus/metabolism , Humans , KCNQ2 Potassium Channel , RatsABSTRACT
A new class of acrylamides was synthesized, and the effects of these analogues on outward potassium current were evaluated by using two electrode voltage clamp recordings from Xenopus laevis oocytes expressing cloned mKCNQ2 channels. SAR studies indicated that the pharmacophore of the acrylamide series includes the (S) absolute configuration at the (1-phenyl)ethyl moiety and the alpha,beta-unsaturated acrylamide functionality with a free NH. This study identified (S)-N-[1-(3-morpholin-4-yl-phenyl)-ethyl]-3-phenyl-acrylamide ((S)-1) and (S)-N-[1-(4-fluoro-3-morpholin-4-yl-phenyl)-ethyl]-3-(4-fluoro-phenyl)-acrylamide ((S)-2) as KCNQ2 openers for further electrophysiological evaluations. These two acrylamides demonstrated significant activity in the cortical spreading depression model of migraine as we reported previously.
Subject(s)
Acrylamides/chemical synthesis , Cinnamates/chemical synthesis , Morpholines/chemical synthesis , Potassium Channels/drug effects , Acrylamides/chemistry , Acrylamides/pharmacology , Animals , Cinnamates/chemistry , Cinnamates/pharmacology , Cortical Spreading Depression/drug effects , Humans , KCNQ2 Potassium Channel , Mice , Morpholines/chemistry , Morpholines/pharmacology , Oocytes/drug effects , Oocytes/physiology , Patch-Clamp Techniques , Potassium Channels/physiology , Potassium Channels, Voltage-Gated , Stereoisomerism , Structure-Activity Relationship , Xenopus laevisABSTRACT
(S)-N-[1-(4-Cyclopropylmethyl-3,4-dihydro-2H-benzo[1,4]oxazin-6-yl)-ethyl]-3-(2-fluoro-phenyl)-acrylamide ((S)-2) was identified as a potent and efficacious KCNQ2 opener. This compound demonstrated significant activity in reducing neuronal hyperexcitability in rat hippocampal slices, and the inhibition mediated by (S)-2 was reversed by the KCNQ blocker linopirdine.
Subject(s)
Acrylamides/pharmacology , Hippocampus/drug effects , Neurons/drug effects , Oxazines/pharmacology , Potassium Channels/drug effects , Acrylamides/chemical synthesis , Animals , Dose-Response Relationship, Drug , Hippocampus/metabolism , Hippocampus/pathology , Humans , KCNQ2 Potassium Channel , Kidney/cytology , Kidney/drug effects , Kidney/metabolism , Mice , Molecular Structure , Neurons/metabolism , Neurons/pathology , Oxazines/chemical synthesis , Patch-Clamp Techniques , Potassium Channels/genetics , Potassium Channels/metabolism , Potassium Channels, Voltage-Gated , Rats , Structure-Activity RelationshipABSTRACT
3-amino-4-benzylquinolin-2-ones have been identified as a novel class of KCNQ2 channel openers. Synthesis and SAR is described along with their electrophysiological evaluation as activators of the cloned mKCNQ2 channel expressed in Xenopus laevis oocytes. The preliminary SAR data suggest the importance of both the trifluoromethylsulfonamido group and electron-withdrawing substituents on the quinolone nucleus for expression of KCNQ2 channel opening properties.
Subject(s)
Potassium Channels/physiology , Quinolones/chemical synthesis , Quinolones/pharmacology , Animals , Female , Ion Channel Gating/drug effects , Ion Channel Gating/physiology , KCNQ2 Potassium Channel , Potassium Channels/agonists , Potassium Channels, Voltage-Gated , Structure-Activity Relationship , Xenopus laevisABSTRACT
Potassium channels have been identified as targets for a large number of therapeutic indications. The ability to use a high-throughput functional assay for the detection and characterization of small-molecule modulators of potassium channels is very desirable. However, present techniques capable of screening very large chemical libraries are limited in terms of data quality, temporal resolution, ease of use, and requirements for specialized instrumentation. To address these issues, the authors have developed a fluorescence-based thallium flux assay. This assay is capable of detecting modulators of both voltage and ligand-gated potassium channels expressed in mammalian cells. The thallium flux assay can use instruments standard to most high-throughput screening laboratories, and using such equipment has been successfully employed to screen large chemical libraries consisting of hundreds of thousands of compounds.