Monoamine Oxidase B Inhibitor Research Articles

Synthesis and structure-activity relationship study of novel 3-heteroarylcoumarins based on pyridazine scaffold as selective MAO-B inhibitors

Compounds of hybrid structure pyridazine-coumarin were discovered as potent, selective and reversible inhibitors of monoamine oxidase B (MAO-B). These compounds were synthesized in good yield following a multistep approach based on Knoevenagel reaction and using as key intermediate pyridazinone 16, which was obtained from maleic anhydride and furan. Compounds 9b and 9d are the most active compounds of these series, with IC50 values in the sub-micromolar range, and lack of cytotoxic effects. Theoretical calculation of ADME properties also suggested a good pharmacokinetic profile for both compounds.Docking simulations provided insights into enzyme inhibitor interactions and allowed us to rationalize the observed structure-activity relationships (SARs).

Monoamine Oxidase B Inhibitors in Parkinson's Disease.

Parkinson's disease (PD) is a neurodegenerative disorder with a prevalence increasing with age. Oxidative stress and glutamate toxicity are involved in its pathomechanism. There are still many unmet needs of PD patients, including the alleviation of motor fluctuations and dyskinesias, and the development of therapies with neuroprotective potential. To give an overview of the pharmacological properties, the efficacy and safety of the monoamine oxidase B (MAO-B) inhibitors in the treatment of PD, with special focus on the results of randomized clinical trials. A literature search was conducted in PubMed for 'PD treatment', 'MAO-B inhibitors', 'selegiline', 'rasagiline', 'safinamide' and 'clinical trials' with 'MAO-B inhibitors' in 'Parkinson' disease'. MAO-B inhibitors have a favorable pharmacokinetic profile, improve the dopamine deficient state and may have neuroprotective properties. Safinamide exhibits an anti-glutamatergic effect as well. When applied as monotherapy, MAO-B inhibitors provide a modest, but significant improvement of motor function and delay the need for levodopa. Rasagiline and safinamide were proven safe and effective when added to a dopamine agonist in early PD. As add-on to levodopa, MAO-B inhibitors significantly reduced off-time and were comparable in efficacy to COMT inhibitors. Improvements were achieved as regards certain non-motor symptoms as well. Due to the efficacy shown in clinical trials and their favorable side-effect profile, MAO-B inhibitors are valuable drugs in the treatment of PD. They are recommended as monotherapy in the early stages of the disease and as add-on therapy to levodopa in advanced PD.

EFFICACY OF EXTENDED-RELEASE CARBIDOPA-LEVODOPA WITH OR WITHOUT THE USE OF OTHER PD MEDICATIONS

Introduction: Carbidopa-levodopa extended-release capsules (ER CD-LD, IPX066) significantly improves motor symptoms and activities of daily living in early and advanced Parkinson’s disease (PD). ER CD-LD produces an initial peak in plasma levodopa concentrations at about one hour, which are maintained for about 4–5 hours before declining. Methods: The safety and efficacy of ER CD-LD vs. immediate-release (IR) CD-LD was examined in a randomized, double-blind, active-controlled, Phase 3 study. Efficacy measures (PD diary and Unified PD Rating Scale [UPDRS] Parts II [activities of daily living] + III [motor score]) were analyzed to evaluate the effect of concomitant use or non-use of dopamine agonists (DA), monoamine oxidase-B (MAO-B) inhibitors, or amantadine on the response to ER CD-LD. Results: In the overall study (N=393), ER CD-LD improved “off” time (P<.0001), “on” time without troublesome dyskinesia (P=.0002), and UPDRS Parts II+III scores (P<.0001) vs. IR CD-LD. Numerical improvements from baseline in PD diary measures and UPDRS Parts II+III were seen with ER CD-LD vs. IR CD-LD in each subgroup. Improvements in “off” time and “on” time without troublesome dyskinesia were significant (P<.05) for ER CD-LD vs. IR in each subgroup, except for the group using concomitant amantadine (P>.50). ER CD-LD did not significantly worsen “on” time with troublesome dyskinesia vs. IR in any subgroup (P>.11). The most frequent adverse events were similarly reported across subgroups. Conclusions: The concomitant use or non-use of adjunctive PD medications did not affect the efficacy or degree of troublesome dyskinesias when ER CD-LD was compared to IR CD-LD.

Iron modulates the activity of monoamine oxidase B in SH-SY5Y cells.

Both monoamine oxidase B (MAO-B) and iron accumulation are associated with neurologic diseases including Parkinson's disease. However, the association of iron with MAO-B activity was poorly understood. Here we took advantage of highly sensitive and specific fluorescence probes to examine the change in MAO-B activity in human dopaminergic neuroblastoma (SH-SY5Y) cells upon iron exposure. Both ferric and ferrous ions could significantly enhance the activity of MAO-B, instead of MAO-A, in SH-SY5Y cells. In addition, iron-induced increase in MAO-B probe fluorescence could be prevented by pargyline and other newly developed MAO-B inhibitors, suggesting that it was MAO-B activity-dependent. These findings may suggest MAO-B is an important sensor in iron-stressed neuronal cells.

Sembragiline: A Novel, Selective Monoamine Oxidase Type B Inhibitor for the Treatment of Alzheimer's Disease.

Monoamine oxidase B (MAO-B) has been implicated in the pathogenesis of Alzheimer's disease (AD) and other neurodegenerative disorders. Increased MAO-B expression in astroglia has been observed adjacent to amyloid plaques in AD patient brains. This phenomenon is hypothesized to lead to increased production of hydrogen peroxide and reactive oxygen species (ROS), thereby contributing to AD pathology. Therefore, reduction of ROS-induced oxidative stress via inhibition of MAO-B activity may delay the progression of the disease. In the present study we report the pharmacological properties of sembragiline, a novel selective MAO-B inhibitor specifically developed for the treatment of AD, and on its effect on ROS-mediated neuronal injury and astrogliosis in MAO-B transgenic animals. Sembragiline showed potent and long-lasting MAO-B-selective inhibition and did not inhibit MAO-A at doses where full inhibition of MAO-B was observed. Such selectivity should translate into a favorable clinical safety profile. Indeed, sembragiline neither induced the serotonin syndrome when administered together with the serotonin precursor l-5-hydroxytryptophan in combination with antidepressants such as fluoxetine, nor potentiated the pressor effect of tyramine. Additionally, in experiments using a transgenic animal model conditionally overexpressing MAO-B in astroglia, sembragiline protected against neuronal loss and reduced both ROS formation and reactive astrogliosis. Taken together, these findings warrant further investigation of the potential therapeutic benefit of MAO-B inhibitors in patients with AD and other neurologic disorders.

Selegiline Ameliorates Depression-Like Behavior in Mice Lacking the CD157/BST1 Gene, a Risk Factor for Parkinson's Disease.

Parkinson’s disease (PD), a neurodegenerative disorder, is accompanied by various non-motor symptoms including depression and anxiety, which may precede the onset of motor symptoms. Selegiline is an irreversible monoamine oxidase-B (MAO-B) inhibitor, and is widely used in the treatment of PD and major depression. However, there are few reports about the effects of selegiline on non-motor symptoms in PD. The aim of this study was to explore the antidepressant and anxiolytic effects of selegiline, using CD157/BST1 knockout (CD157 KO) mouse, a PD-related genetic model displaying depression and anxiety, compared with other antiparkinsonian drugs and an antidepressant, and was to investigate the effects of selegiline on biochemical parameters in emotion-related brain regions. A single administration of selegiline (1–10 mg/kg) dose-dependently reduced immobility time in the forced swimming test (FST) in CD157 KO mice, but not C57BL/6N wild-type (WT) mice. At 10 mg/kg, but not 3 mg/kg, selegiline significantly increased climbing time in CD157 KO mice. A single administration of the antiparkinsonian drugs pramipexole (a dopamine (DA) D2/D3 receptor agonist) or rasagiline (another MAO-B inhibitor), and repeated injections of a noradrenergic and specific serotonergic antidepressant (NaSSA), mirtazapine, also decreased immobility time, but did not increase climbing time, in CD157 KO mice. The antidepressant-like effects of 10 mg/kg selegiline were comparable to those of 10 mg/kg rasagiline, and tended to be stronger than those of 1 mg/kg rasagiline. After the FST, CD157 KO mice showed decreases in striatal and hippocampal serotonin (5-HT) content, cortical norepinephrine (NE) content, and plasma corticosterone concentration. A single administration of selegiline at 10 mg/kg returned striatal 5-HT, cortical NE, and plasma corticosterone levels to those observed in WT mice. In the open field test (OFT), repeated administration of mirtazapine had anxiolytic effects, and selegiline nonsignificantly ameliorated anxiety-like behaviors in CD157 KO mice. In the social interaction and preference tests, repeated mirtazapine ameliorated the high anxiety and low sociability of CD157 KO mice, whereas selegiline did not. These results indicate that selegiline has antidepressant and mild anxiolytic effects in CD157 KO mice, and suggest that it is an effective antiparkinsonian drug for depressive and anxiety symptoms in PD patients with a CD157 single nucleotide polymorphism (SNP).

Monoamine oxidase B inhibitor, selegiline, reduces 18F-THK5351 uptake in the human brain

Background18F-THK5351 is a quinoline-derived tau imaging agent with high affinity to paired helical filaments (PHF). However, high levels of 18F-THK5351 retention in brain regions thought to contain negligible concentrations of PHF raise questions about the interpretation of the positron emission tomography (PET) signals, particularly given previously described interactions between quinolone derivatives and monoamine oxidase B (MAO-B). Here, we tested the effects of MAO-B inhibition on 18F-THK5351 brain uptake using PET and autoradiography.MethodsEight participants (five mild cognitive impairment, two Alzheimer’s disease, and one progressive supranuclear palsy) had baseline 18F-AZD4694 and 18F-THK5351 scans in order to quantify brain amyloid and PHF load, respectively. A second 18F-THK5351 scan was conducted 1 week later, 1 h after a 10-mg oral dose of selegiline. Three out of eight patients also had a third 18F-THK5351 scan 9–28 days after the selegiline administration. The primary outcome measure was standardized uptake value (SUV), calculated using tissue radioactivity concentration from 50 to 70 min after 18F-THK5351 injection, normalizing for body weight and injected radioactivity. The SUV ratio (SUVR) was determined using the cerebellar cortex as the reference region. 18F-THK5351 competition autoradiography studies in postmortem tissue were conducted using 150 and 500 nM selegiline.ResultsAt baseline, 18F-THK5351 SUVs were highest in the basal ganglia (0.64 ± 0.11) and thalamus (0.62 ± 0.14). In the post-selegiline scans, the regional SUVs were reduced on average by 36.7% to 51.8%, with the greatest reduction noted in the thalamus (51.8%) and basal ganglia (51.4%). MAO-B inhibition also reduced 18F-THK5351 SUVs in the cerebellar cortex (41.6%). The SUVs remained reduced in the three patients imaged at 9–28 days. Tissue autoradiography confirmed the effects of MAO-B inhibition on 18F-THK5351 uptake.ConclusionsThese results indicate that the interpretation of 18F-THK5351 PET images, with respect to tau, is confounded by the high MAO-B availability across the entire brain. In addition, the heterogeneous MAO-B availability across the cortex may limit the interpretation of 18F-THK5351 scans using reference region methods.

Simultaneous determination of MAO-A and -B activity following first time intake of an irreversible MAO-B inhibitor in patients with Parkinson's disease.

We determined monoamine oxidase-A (plasma) and -B (platelets) enzyme activity in chronic levodopa treated patients with Parkinson's disease after first time intake of an irreversible monoamine oxidase-B inhibitor. One patient received 10mg selegiline and eleven patients took 1mg rasagiline. A significant decrease of monoamine oxidase-B activity appeared 2 and 4h following monoamine oxidase-B inhibitor intake in comparison to baseline. We confirm with this design, that rasagiline and selegiline inhibit monoamine oxidase-B but not monoamine oxidase-A after single dosing.

Efficacy of rasagiline for the treatment of Parkinson’s disease: an updated meta-analysis

Objective: Rasagiline is a second-generation potent selective inhibitor of monoamine oxidase-B. The aim of the study was to analyze the effectiveness of rasagiline in treatment of Parkinson’s disease (PD), both as monotherapy and combination therapy.Methods: Medline, Cochrane, EMBASE, and Google Scholar databases were searched until 9 March 2016 using the keywords: Rasagiline, Azilect, Parkinson’s disease. Randomized controlled trials of patients with PD who were randomized to treatment with rasagiline or placebo were included. Outcomes were unified Parkinson’s disease rating scale (UPDRS) and the three subscales.Results: Ten studies fulfilled the inclusion criteria and 2709 patients were evaluated. The overall analysis revealed a significant improvement in change of total UPDRS scores in 1 mg/day and 2 mg/day rasagiline groups compared to placebo. Significant improvement in Part I (Mentation) of UPDRS scores was observed in 1 mg/day, but not in 2 mg/day rasagiline treatment group. Part II (ADL) and Part III (Motor) subscales significantly improved with both doses of rasagiline. Both monotherapy and combination therapy significantly improved total UPDRS scores.Conclusions: Our results confirm the efficacy of rasagiline in PD. Further studies are required to establish the optimal dose of rasagiline, as well as to determine its effectiveness in different combination therapy protocols.KEY MESSAGESRasagiline treatment was associated with significant improvement of UPDRS scores and the scores of the subscales.Both monotherapy and combination therapy significantly improved total UPDRS scores.Effect of rasagiline on total UPDRS scores was not dose-dependent.

The neuroprotective agent Rasagiline mesylate attenuates cardiac remodeling after experimental myocardial infarction.

AimRasagiline mesylate (N‐propargyl‐1 (R)‐aminoindan) (RG) is a selective, potent irreversible inhibitor of monoamine oxidase‐B with cardioprotective and anti‐apoptotic properties. We investigated whether it could be cardioprotective in a rat model undergoing experimental myocardial infarction (MI) by permanent ligation of the left anterior descending coronary artery.Methods and resultsRG was administered, intraperitoneally, for 28 days (2 mg/kg) starting 24 h after MI induction. Echocardiography analysis revealed a significant reduction in left ventricular end‐systolic and diastolic dimensions and preserved fractional shortening in RG‐treated compared with normal saline group at 28 days post‐MI (31.6 ± 2.3 vs. 19.6 ± 1.8, P < 0.0001), respectively. Treatment with RG prevented tissue fibrosis as indicated by interstitial collagen estimation by immunofluorescence staining and hydroxyproline content and attenuated the number of apoptotic myocytes in the border zone (65%) as indicated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Caspase 3 relative protein levels were significantly decreased in the non‐infarcted myocardium. Markedly decreased malondialdehyde levels in the border zone indicate a reduction in tissue oxidative stress.ConclusionsOur study demonstrates a positive effect of RG in the post‐MI period with a significant attenuation in cardiac remodelling.

Discovery of highly selective and potent monoamine oxidase B inhibitors: Contribution of additional phenyl rings introduced into 2-aryl-1,3,4-oxadiazin-5(6H)-one

Monoamine oxidase B (MAO-B) is a flavin adenine dinucleotide (FAD)-containing enzyme that plays a major role in the oxidative deamination of biogenic amines and neurotransmitters. Inhibiting MAO-B activity is a promising approach in the treatment of neurological disorders. Here, we report a series of 2-aryl-1,3,4-oxadiazin-5(6H)-one derivatives as highly selective and potent MAO-B inhibitors. Analysis of the binding sites of hMAO-A and hMAO-B led to design of linear analogs of 2-aryl-1,3,4-oxadiazin-5(6H)-one with an additional phenyl ring. Biological evaluation of the 26 new derivatives resulted in the identification of highly potent and selective inhibitors with optimal physicochemical properties to potentially cross the blood-brain barrier (BBB). Compounds 18a, 18b, 18e and 25b potently inhibited MAO-B, with IC50 values of 4–25 nM and excellent SI over MAO-A (18a > 25000, 18b > 8333 and 18e > 4000 and 25b > 4545). Docking results suggest that an optimal linker between two aromatic rings on the 2-aryl-1,3,4-oxadiazin-5(6H)-one scaffold is a key element in the binding and inhibition of MAO-B.

Pharmacophore-Based 3D-QSAR Analysis of Thienyl Chalcones as a New Class of Human MAO-B Inhibitors: Investigation of Combined Quantum Chemical and Molecular Dynamics Approach.

Selective monoamine oxidase-B (MAO-B) inhibitors are imperative in the treatment of various neurodegenerative disorders. Herein, we describe the pharmacophore generation and atom-based three-dimensional quantitative structure-activity relationship (3D-QSAR) analyses of previously reported thiophene-based hMAO-B inhibitors by our research group. The aim of this study was to identify the principal structural features that could potentially be responsible for the inhibitory activity of hMAO-B inhibitors. The best pharmacophore model generated was the four-point assay of AHRR.8. The pharmacophore model exhibited good correlation with its predictability of the statistically valid 3D-QSAR analyses. Density functional theory calculations were further employed on the lead molecule (2E)-1-(5-bromothiophen-2-yl)-3-[4-(dimethylamino) phenyl] prop-2-en-1-one (Tb5) to investigate the electrostatic potential surface and analyze the natural bond orbital toward the binding characteristics. Molecular dynamics simulations were performed to characterize the molecular level interactions and relative energies of the hMAO isoforms: hMAO-A and hMAO-B with three potent and selective hMAO-B inhibitors (Tb5, Tb6, and Tb9). The results of both continuous and accelerated molecular dynamics simulations demonstrate a distinct preference of the three ligands to bind to hMAO-B rather than hMAO-A.

Safinamide: A Review in Parkinson's Disease.

Safinamide (Xadago®) is an orally active, selective, reversible monoamine oxidase-B inhibitor with both dopaminergic and non-dopaminergic (glutamatergic) properties. In the EU, safinamide is approved for the treatment of mid- to late-stage fluctuating Parkinson's disease (PD) as add-on therapy to a stable dose of levodopa alone or in combination with other PD medications. Safinamide 50-100mg/day administered as a fixed or flexible dose significantly increased daily 'on' time without dyskinesia (primary endpoint) in patients with mid- to late-stage PD with motor fluctuations in 24-week, placebo-controlled clinical trials. Other outcomes, including motor function, overall clinical status and health-related quality of life, were also generally improved with safinamide. Furthermore, in an 18-month extension of one study, although dyskinesia (primary endpoint) was not significantly improved with safinamide relative to placebo, treatment benefits in other outcomes were generally sustained over 24months of treatment. Safinamide was generally well tolerated in clinical trials; dyskinesia was the most common adverse event. Although further studies are needed, including comparative and long-term studies, current evidence indicates that safinamide extends the treatment options available for use as add-on therapy to levodopa and other PD medications in patients with mid- to late-stage PD experiencing motor fluctuations.

Inhibition of monoamine oxidase-B by selegiline reduces cigarette smoke-induced oxidative stress and inflammation in airway epithelial cells

Chronic obstructive pulmonary disease (COPD) is caused by the build-up of oxidative stress-induced damages due to cigarette smoking, but how monoamine oxidase (MAO)-B signaling is involved remains unclear. This study aims to establish the involvement of MAO-B signaling pathways in cigarette smoke medium (CSM)-induced oxidative stress and inflammation in human airway epithelial cells (AECs). CSM treatment increased MAO-B activity, ROS levels and IL-8 release in AECs. Pretreatment with MAO-B selective inhibitor selegiline reversed the CSM-induced changes in MAO-B activity, ROS levels and IL-8 release in a dose-dependent manner. Selegiline also reversed CSM-induced changes of anti-oxidant enzymes superoxide dismutase (SOD) and catalase (CAT) activities, GSH/GSSG ratio, as well expression of heme oxygenase-1 (HO-1) and NAD(P)H quinone dehydrogenase 1 (NQO1). The effects of selegiline are partially driven through the nuclear factor erythroid 2 related factor 2 (Nrf2) and cytosolic translocation of its negative regulator, BTB and CNC homolog 1 (Bach1). Nevertheless, selegiline fully reversed the CSM-induced effects on IKK, cytoplasmic IκB expression, and nuclear translocation of nuclear factor-κB (NF-κB) p65 subunit. Our study demonstrated that in AECs, inhibition of MAO-B using selegiline reversed the CSM-induced oxidative stress and inflammation. These data may provide a novel strategy for therapy in COPD.

Visible-light assisted one-pot preparation of aryl glyoxals from acetoarylones via in-situ arylacyl bromides formation: Selenium-free approach to acetoarylones oxidation

A novel visible-light (blue LEDs: hν=425±15nm) photocatalyzed one-pot method for the synthesis of electronically diverse aryl glyoxals in good to excellent yields from acetoarylones and green regents such as air, vitamin C and dioxane dibromide has been described. In addition, an application of the current methodology has been demonstrated for the oxidation of monoamine oxidase-B inhibitors, i.e., 1-(4-((4-fluorobenzyl)oxy)phenyl)ethanone and 1-(3-((4-chlorobenzyl)oxy)phenyl)ethanone. This finding may serves as a valuable alternative to the traditional acetoarylones oxidation reactions conducted using selenium dioxide a harmful and unselective reagent known to simultaneously oxidize allylic, benzylic, CH3 and so on.

PARKINSON DAN TERAPI STEM SEL

Parkinson's disease is a neurodegenerative disorder that is progressive about the movement or control of movement. The disease often occurs in people over the age of 60 years. The etiology of Parkinson's disease caused by a combination of genetic and environmental factors. Because overall life expectancy increases, the number of people with Parkinson's disease will increase in the future. Treatment of Parkinson's disease can be used with pharmacological therapy and nonpharmacological therapy. Pharmacological therapy can use levodopa, monoamine oxidase-B inhibitors, dopamine agonists, anticholinergics and amantadine, while nonpharmacological therapies may use the method of stem cell therapy. Stem cells are master cells that have two important characteristics that can perform self-renewing through cell division and can be induced to become cells with specific functions. The aim of Stem cell therapy in Parkinson's disease to replace the damaged dopaminergic cells.

Histamine H3 Receptors and Its Antagonism as a Novel Mechanism for Antipsychotic Effect : A Current Preclinical and Clinical Perspective

Histamine H3 receptors are present as autoreceptors on histaminergic neurons and as heteroreceptors on nonhistaminergic neurones. They control the release and synthesis of histamine and several other key neurotransmitters in the brain. H3 antagonism may be a novel approach to develop a new class of antipsychotic medications given the gathering evidence reporting therapeutic efficacy in several central nervous system disorders. Several medications such as cariprazine, lurasidone, LY214002, bexarotene, rasagiline, raloxifene, BL-1020 and ITI-070 are being developed to treat the negative symptoms and cognitive impairments of schizophrenia. These medications works through diverse mechanisms which include agonism at metabotropic glutamate receptor (mGluR2/3), partial agonism at dopamine D2, D3 and serotonin 5-HT1A receptors, antagonism at D2, 5-HT2A, 5-HT2B and 5-HT7 receptors, combined dopamine antagonism with GABA agonist activity, inhibition of monoamine oxidase-B, modulation of oestrogen receptor, and activation of nuclear retinoid X receptor. However, still specific safe therapy for psychosis remains at large. Schizophrenia is a severe neuropsychiatric disorder result both from hyper- and hypo-dopaminergic transmission causing positive and negative symptoms, respectively. Pharmacological stimulation of dopamine release in the prefrontal cortex has been a viable approach in treating negative symptoms and cognitive deficits of schizophrenia symptoms that are currently not well treated and continue to represent significant unmet medical challenges. Administration of H3 antagonists/inverse agonists increase extracellular dopamine concentrations in rat prefrontal cortex, but not in the striatum suggesting that antagonism via H3 receptor may be a potential target for treating negative symptoms and cognitive deficits associated with schizophrenia. Further, insights are emerging into the potential role of histamine H3 receptors as a target of antiobesity therapeutics which is one of the limiting adverse effects of second generation schizophrenia medications. The recent failures of two promising H3 compounds in clinical trial dampened the interest in seeking antipsychotic like activities of H3 receptor antagonists. However, due to the inconclusive nature of many of these studies, the development of H3 compounds via H3 antagonism/inverse agonism approach still hold lot of promises and may be developed as a novel class of drugs for schizophrenia and its related complications e.g. weight gain.

Monoamine Oxidase Inhibitory Activity: Methyl- versus Chlorochalcone Derivatives.

Numerous studies have shown that chalcones are promising scaffolds for the development of new monoamine oxidase-B (MAO-B) inhibitors. As a continuation of our ongoing research into the development of reversible human MAO-B (hMAO-B) inhibitors, two series of twenty chalcones containing electron-donating and electron-withdrawing substituents were synthesized. All compounds were found to be competitive, selective, and reversible inhibitors of hMAO-B except (2E)-1-(4-methylphenyl)-3-(4-nitrophenyl)prop-2-en-1-one (P7) and (2E)-1-(4-chlorophenyl)-3-(4-nitrophenyl)prop-2-en-1-one (P17), which were found to be selective inhibitors of hMAO-A. The most potent hMAO-B inhibitor, (2E)-1-(4-chlorophenyl)-3-(4-ethylphenyl)prop-2-en-1-one (P16), showed a Ki value of 0.11±0.01 μm. Molecular docking simulations were carried out to identify the hypothetical binding mode for the most potent compounds in the active sites of hMAO-A and B. The ability of the compounds to cross the blood-brain barrier was assessed by parallel artificial membrane permeability assay (PAMPA). Additionally, the most potent hMAO-B inhibitor P16 showed no toxicity in cultured hepatic cells at concentrations of 5 and 25 μm.

N-Propargylpiperidines with naphthalene-2-carboxamide or naphthalene-2-sulfonamide moieties: Potential multifunctional anti-Alzheimer’s agents

In the brains of patients with Alzheimer’s disease, the enzymatic activities of butyrylcholinesterase (BChE) and monoamine oxidase B (MAO-B) are increased. While BChE is a viable therapeutic target for alleviation of symptoms caused by cholinergic hypofunction, MAO-B is a potential therapeutic target for prevention of neurodegeneration in Alzheimer’s disease. Starting with piperidine-based selective human (h)BChE inhibitors and propargylamine-based MAO inhibitors, we have designed, synthesized and biochemically evaluated a series of N-propargylpiperidines. All of these compounds inhibited hBChE with good selectivity over the related enzyme, acetylcholinesterase, and crossed the blood-brain barrier in a parallel artificial membrane permeation assay. The crystal structure of one of the inhibitors (compound 3) in complex with hBChE revealed its binding mode. Three compounds (4, 5, 6) showed concomitant inhibition of MAO-B. Additionally, the most potent hBChE inhibitor 7 and dual BChE and MAO-B inhibitor 6 were non-cytotoxic and protected neuronal SH-SY5Y cells from toxic amyloid β-peptide species.

Clinical Pharmacokinetics and Pharmacodynamics of Safinamide.

The symptoms of Parkinson's disease (PD) reflect disruptions of a number of brain neurotransmitter systems of varying type and degree. Pharmacological agents with multiple neurochemical mechanisms of action are therefore promising candidates for countering these problems and providing comprehensive symptomatic relief for patients. The pharmacological profile of safinamide includes reversible monoamine oxidaseB inhibition, blockage of voltage-dependent Na+ channels, modulation of Ca2+ channels, and inhibition of glutamate release. Safinamide is administered once daily at oral doses of 50-100mg; it is well-tolerated and safe. Clinical trials have found that it ameliorates motor symptoms when added to established levodopa or single dopamine receptor agonist therapy. The future role of safinamide in PD may be that it enables a reduction in the dosage of dopamine replacement therapies, thereby reducing the adverse effects associated with these treatments. The clinical convenience (once-daily administration), safety, and tolerability of safinamide are better than those of dopamine receptor agonists. The introduction of safinamide reflects a change of approach to drug development for anti-parkinsonian agents in that its broad spectrum of action corresponds to the multiple heterogeneous alterations of brain neurochemistry in PD, rather than being targeted at a single receptor type or neurochemical process. Safinamide is a promising new instrument for the effective symptomatic therapy of PD.