The safety and efficacy of safinamide mesylate for the treatment of Parkinson's disease

Isatin-based benzyloxybenzene derivatives as monoamine oxidase inhibitors with neuroprotective effect targeting neurogenerative disease treatment

Eighteen isatin-based benzyloxybenzaldehyde derivatives from three subseries, ISB, ISFB, and ISBB, were synthesized and their ability to inhibit monoamine oxidase (MAO) was evaluated. The inhibitory activity of all synthesized compounds was found to be more profound against MAO-B than MAO-A. Compound ISB1 most potently inhibited MAO-B with an IC50 of 0.124 ± 0.007 μM, ensued by ISFB1 (IC50 = 0.135 ± 0.002 μM). Compound ISFB1 most potently inhibited MAO-A with an IC50 of 0.678 ± 0.006 μM, ensued by ISBB3 (IC50 = 0.731 ± 0.028 μM), and had the highest selectivity index (SI) value (55.03). The three sub-parental compounds, ISB1, ISFB1, and ISBB1, had higher MAO-B inhibition than the other derivatives, indicating that the substitutions of the 5-H in the A-ring of isatin diminished the inhibition of MAO-A and MAO-B. Among these, ISB1 (para-benzyloxy group in the B-ring) displayed more significant MAO-B inhibition when compared to ISBB1 (meta-benzyloxy group in the B-ring). ISB1 and ISFB1 were identified to be competitive and reversible MAO-B inhibitors, having Ki values of 0.055 ± 0.010, and 0.069 ± 0.025 μM, respectively. Furthermore, in the parallel artificial membrane penetration assay, ISB1 and ISFB1 traversed the blood-brain barrier in the in vitro condition. Additionally, the current study found that ISB1 decreased rotenone-induced cell death in SH-SY5Y neuroblastoma cells. In docking and simulation studies, the hydrogen bonding formed by the imino nitrogen in ISB1 and the pi-pi stacking interaction of the phenyl ring in isatin significantly aided in the protein-ligand complex's stability, effectively inhibiting MAO-B. According to these observations, the MAO-B inhibitors ISB1 and ISFB1 were potent, selective, and reversible, making them conceivable therapies for neurological diseases.

Sigma-1 receptor and seizures

Over the last decade, sigma-1 receptor (Sig1R) has been recognized as a valid target for the treatment of seizure disorders and seizure-related comorbidities. Clinical trials with Sig1R ligands are underway testing therapies for the treatment of drug-resistant seizures, developmental and epileptic encephalopathies, and photosensitive epilepsy. However, the direct molecular mechanism by which Sig1R modulates seizures and the balance between excitatory and inhibitory pathways has not been fully elucidated. This review article aims to summarize existing knowledge of Sig1R and its involvement in seizures by focusing on the evidence obtained from Sig1R knockout animals and the anti-seizure effects of Sig1R ligands. In addition, this review article includes a discussion of the advantages and disadvantages of the use of existing compounds and describes the challenges and future perspectives on the use of Sig1R as a target for the treatment of seizure disorders.

Development of Isopropyl-Tailed Chalcones as a New Class of Selective MAO-B Inhibitors for the Treatment of Parkinson's Disorder

Thirteen isopropyl chalcones (CA1-CA13) were synthesized and evaluated for their inhibitory activity against monoamine oxidase (MAO). All compounds inhibited MAO-B more effectively than MAO-A. Compound CA4 most potently inhibited MAO-B with an IC₅₀ value of 0.032 μM, similar to that of CA3 (IC₅₀ = 0.035 μM) and with high selectivity index (SI) values for MAO-B over MAO-A (SI = 49.75 and 353.23, respectively). The -OH (CA4) or -F (CA3) group at the para position on the A ring provided higher MAO-B inhibition than that of the other substituents (-OH ≥ -F > -Cl > -Br > -OCH₂CH₃ > -CF₃). On the other hand, compound CA10 most potently inhibited MAO-A with an IC₅₀ value of 0.310 μM and effectively MAO-B (IC₅₀ = 0.074 μM). The Br-containing thiophene substituent (CA10) instead of the A ring showed the highest MAO-A inhibition. In a kinetic study, K _i values of compounds CA3 and CA4 for MAO-B were 0.076 ± 0.001 and 0.027 ± 0.002 μM, respectively, and that of CA10 for MAO-A was 0.016 ± 0.005 μM. A reversibility study showed that CA3 and CA4 were reversible inhibitors of MAO-B and CA10 was a reversible inhibitor of MAO-A. In docking and molecular dynamics, the hydroxyl group of CA4 and two hydrogen bonds contributed to the stability of the protein-ligand complex. These results suggest that CA3 and CA4 are potent reversible selective MAO-B inhibitors and can be used for the treatment of Parkinson's disease.

Revisiting the Role of Astrocytic MAOB in Parkinson's Disease

Monoamine oxidase-B (MAOB) has been believed to mediate the degradation of monoamine neurotransmitters such as dopamine. However, this traditional belief has been challenged by demonstrating that it is not MAOB but MAOA which mediates dopamine degradation. Instead, MAOB mediates the aberrant synthesis of GABA and hydrogen peroxide (H₂O₂) in reactive astrocytes of Parkinson’s disease (PD). Astrocytic GABA tonically suppresses the dopaminergic neuronal activity, whereas H₂O₂ aggravates astrocytic reactivity and dopaminergic neuronal death. Recently discovered reversible MAOB inhibitors reduce reactive astrogliosis and restore dopaminergic neuronal activity to alleviate PD symptoms in rodents. In this perspective, we redefine the role of MAOB for the aberrant suppression and deterioration of dopaminergic neurons through excessive GABA and H₂O₂ synthesis of reactive astrocytes in PD.

Solid-State Study of the Structure, Dynamics, and Thermal Processes of Safinamide Mesylate─A New Generation Drug for the Treatment of Neurodegenerative Diseases

Safinamide mesylate (SM), the pure active pharmaceutical ingredient (API) recently used in Parkinson disease treatment, recrystallized employing water–ethanol mixture of solvents (vol/vol 1:9) gives a different crystallographic form compared to SM in Xadago tablets. Pure SM crystallizes as a hemihydrate in the monoclinic system with the P2₁ space group. Its crystal and molecular structure were determined by means of cryo X-ray crystallography at 100 K. SM in the Xadago tablet exists in anhydrous form in the orthorhombic crystallographic system with the P2₁2₁2₁ space group. The water migration and thermal processes in the crystal lattice were monitored by solid-state NMR spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. SM in Xadago in the high-humidity environment undergoes phase transformation to the P2₁ form which can be easily reversed just by heating up to 80 °C. For the commercial form of the API, there is also a reversible thermal transformation observed between Z′ = 1 ↔ Z′ = 3 crystallographic forms in the 0–20 °C temperature range. Analysis of molecular motion in the crystal lattice proves that the observed conformational polymorphism is forced by intramolecular dynamics. All above-mentioned processes were analyzed and described employing the NMR crystallography approach with the support of advanced theoretical calculations.

Safinamide Improves Non-Motor Symptoms Burden in Parkinson's Disease: An Open-Label Prospective Study

Some studies observed a benefit of Parkinson's disease (PD) patients after treatment with safinamide in some non-motor symptoms (NMSs). The aim of this study was to analyze the effectiveness of safinamide on NMS burden in PD. SAFINONMOTOR (an open-label study of the effectiveness of safinamide on non-motor symptoms in Parkinson's disease patients) is a prospective open-label single-arm study conducted in five centers from Spain. The primary efficacy outcome was the change from baseline (V1) to the end of the observational period (6 months) (V4) in the non-motor symptoms scale (NMSS) total score. Between May/2019 and February/2020 50 patients were included (age 68.5 ± 9.12 years; 58% females; 6.4 ± 5.1 years from diagnosis). At 6 months, 44 patients completed the follow-up (88%). The NMSS total score was reduced by 38.5% (from 97.5 ± 43.7 in V1 to 59.9 ± 35.5 in V4; p < 0.0001). By domains, improvement was observed in sleep/fatigue (-35.8%; p = 0.002), mood/apathy (-57.9%; p < 0.0001), attention/memory (-23.9%; p = 0.026), gastrointestinal symptoms (-33%; p = 0.010), urinary symptoms (-28.3%; p = 0.003), and pain/miscellaneous (-43%; p < 0.0001). Quality of life (QoL) also improved with a 29.4% reduction in the PDQ-39SI (from 30.1 ± 17.6 in V1 to 21.2 ± 13.5 in V4; p < 0.0001). A total of 21 adverse events in 16 patients (32%) were reported, 5 of which were severe (not related to safinamide). Dyskinesias and nausea were the most frequent (6%). Safinamide is well tolerated and improves NMS burden and QoL in PD patients with severe or very severe NMS burden at 6 months.

A Spanish Consensus on the Use of Safinamide for Parkinson's Disease in Clinical Practice

Safinamide is an approved drug for the treatment of fluctuations in Parkinson's disease (PD). Scarce data are available on its use in clinical practice. A group of Spanish movement disorders specialists was convened to review the use of safinamide across different clinical scenarios that may guide neurologists in clinical practice. Eight specialists with recognized expertise in PD management elaborated the statements based on available evidence in the literature and on their clinical experience. The RAND/UCLA method was carried, with final conclusions accepted after a 2-round modified Delphi process. Higher level of agreement between panellists was reached for the following statements. Safinamide significantly improves mean daily ON time without troublesome dyskinesias [corrected]. Adjunctive treatment with safinamide is associated with motor improvements in patients with mid-to-late PD. The efficacy of safinamide on motor fluctuations is maintained at long-term, with no increase over time in dyskinesias severity. The clinical benefits of safinamide on pain and depression remain unclear. Safinamide presents a similar incidence of adverse events compared with placebo. The efficacy and safety of safinamide shown in the pivotal clinical trials are reproduced in clinical practice, with improvement of parkinsonian symptoms, decrease of daily OFF time, control of dyskinesias at the long term, and good tolerability and safety.

Study on antrodia camphorata polysaccharide in alleviating the neuroethology of PD mice by decreasing the expression of NLRP3 inflammasome

Parkinson's disease (PD) is a neurodegenerative disease, and the role of neuroinflammation in the pathogenesis and progression of PD has been confirmed. The polysaccharides and triterpenoids of antrodia camphorata (a polyporous fungus) harbor diverse and powerful pharmacological effects. In this study, 6-hydroxydopamine was used to construct a PD mouse model. After antrodia camphorata polysaccharide (ACP) intervention, neurobehavioral changes were detected, neurotransmitter changes in striatum were determined by high-performance liquid chromatography, the alterations of striatal NOD-like receptor pyrin domain containing three (NLRP3) were examined by immunohistochemistry, and the expression of NLRP3, IL-1β, Caspase-1, and proCaspase-1 were detected by western blot. To be specific, the items of neurobehavioral test included open field activity, rotary test, pole test, gait analysis, and swimming test. As a result, 6-hydroxydopamine could lead to PD-like lesions, including tremor, stiffness, attenuated spontaneous activity, and bradykinesia in mice, and the expression of tyrosine hydroxylase in the striatum was decreased. After ACP intervention, the neuroethology of mice was significantly improved, as demonstrated by the elevated levels of dopamine in the striatum and the decreased expression of dopamine in the striatum in NLRP3 inflammasome. NLRP3 inflammasome played an important role in neuroinflammation in PD mice. ACP could reduce the activation of NLRP3 and expression of related inflammatory factors.

The current status of pharmacotherapy for the treatment of Parkinson's disease: transition from single-target to multitarget therapy

Parkinson's disease (PD) is a neurodegenerative disorder characterized by degeneration of dopaminergic neurons. Motor features such as tremor, rigidity, bradykinesia and postural instability are common traits of PD. Current treatment options provide symptomatic relief to the condition but are unable to reverse disease progression. The conventional single-target therapeutic approach might not always induce the desired effect owing to the multifactorial nature of PD. Hence, multitarget strategies have been proposed to simultaneously target multiple proteins involved in the development of PD. Herein, we provide an overview of the pathogenesis of PD and the current pharmacotherapies. Furthermore, rationales and examples of multitarget approaches that have been tested in preclinical trials for the treatment of PD are also discussed.

Structure-Based Specific Detection and Inhibition of Monoamine Oxidases and Their Applications in Central Nervous System Diseases

Monoamine oxidases (MAOs) are the enzymes that catalyze the oxidation of monoamines, such as dopamine, norepinephrine, and serotonin, which serve as key neurotransmitters in the central nervous system (CNS). MAOs play important roles in maintaining the homeostasis of monoamines, and the aberrant expression or activation of MAOs underlies the pathogenesis of monoamine neurotransmitter disorders, including neuropsychiatric and neurodegenerative diseases. Clearly, detecting and inhibiting the activities of MAOs is of great value for the diagnosis and therapeutics of these diseases. Accordingly, many specific detection probes and inhibitors have been developed and substantially contributed to basic and clinical studies of these diseases. In this review, progress in the detecting and inhibiting of MAOs and their applications in mechanism exploration and treatment of neurotransmitter-related disorders is summarized. Notably, how the detection probes and inhibitors of MAOs were developed has been specifically addressed. It is hoped that this review will benefit the design of more effective and sensitive probes and inhibitors for MAOs, and eventually the treatment of monoamine neurotransmitter disorders.

Assessment of Enzyme Inhibition: A Review with Examples from the Development of Monoamine Oxidase and Cholinesterase Inhibitory Drugs

The actions of many drugs involve enzyme inhibition. This is exemplified by the inhibitors of monoamine oxidases (MAO) and the cholinsterases (ChE) that have been used for several pharmacological purposes. This review describes key principles and approaches for the reliable determination of enzyme activities and inhibition as well as some of the methods that are in current use for such studies with these two enzymes. Their applicability and potential pitfalls arising from their inappropriate use are discussed. Since inhibitor potency is frequently assessed in terms of the quantity necessary to give 50% inhibition (the IC50 value), the relationships between this and the mode of inhibition is also considered, in terms of the misleading information that it may provide. Incorporation of more than one functionality into the same molecule to give a multi-target-directed ligands (MTDLs) requires careful assessment to ensure that the specific target effects are not significantly altered and that the kinetic behavior remains as favourable with the MTDL as it does with the individual components. Such factors will be considered in terms of recently developed MTDLs that combine MAO and ChE inhibitory functions.

Old and new challenges in Parkinson's disease therapeutics

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the degeneration of dopaminergic neurons and/or loss od neuronal projections, in several dopaminergic networks. Current treatments for idiopathic PD rely mainly on the use of pharmacologic agents to improve motor symptomatology of PD patients. Nevertheless, so far PD remains an incurable disease. Therefore, it is of utmost importance to establish new therapeutic strategies for PD treatment. Over the last 20 years, several molecular, gene and cell/stem-cell therapeutic approaches have been developed with the aim of counteracting or retarding PD progression. The scope of this review is to provide an overview of PD related therapies and major breakthroughs achieved within this field. In order to do so, this review will start by focusing on PD characterization and current treatment options covering thereafter molecular, gene and cell/stem cell-based therapies that are currently being studied in animal models of PD or have recently been tested in clinical trials. Among stem cell-based therapies, those using MSCs as possible disease modifying agents for PD therapy and, specifically, the MSCs secretome contribution to meet the clinical challenge of counteracting or retarding PD progression, will be more deeply explored.

Through scaffold modification to 3,5-diaryl-4,5-dihydroisoxazoles: new potent and selective inhibitors of monoamine oxidase B

3,5-Diaryl-4,5-dihydroisoxazoles were synthesized and evaluated as monoamine oxidase (MAO) enzyme inhibitors and iron chelators. All compounds exhibited selective inhibitory activity towards the B isoform of MAO in the nanomolar concentration range. The best performing compound was preliminarily evaluated for its ability to bind iron II and III cations, indicating that neither iron II nor iron III is coordinated. The best compounds racemic mixtures were separated and single enantiomers inhibitory activity evaluated. Furthermore, none of the synthesised compounds exhibited activity towards MAO A. Overall, these data support our hypothesis that 3,5-diaryl-4,5-dihydroisoxazoles are promising scaffolds for the design of neuroprotective agents.

Emerging approaches in Parkinson's disease - adjunctive role of safinamide

Ongoing neuronal death in Parkinson’s disease (PD) causes an altered neurotransmission of various biogenic amines, particularly dopamine. As these changes do not follow a distinct pattern, they vary individually, and are differently pronounced. As a result, a heterogeneous onset of motor and nonmotor features occurs in each patient with PD during the whole course of the disease. PD actually describes a set of distinct diseases that manifest themselves in clinical syndromes with certain similarities but also great differences. This clinical picture responds to drugs with a broad spectrum of modes of actions better than to compounds with an exclusive focus on specific receptor subtypes. Therefore, safinamide is an ideal candidate for treatment of patients with PD, since its pharmacological profile includes reversible monoamine oxidase-B inhibition, blockade of voltage-dependent sodium channels, modulation of calcium channels, and inhibition of glutamate release. Safinamide is applied only once daily. Its oral dose ranges from 50 to 100 mg. Safinamide was well tolerated and safe in the clinical development program that demonstrated the amelioration of motor symptoms and OFF phenomena by safinamide when combined with dopamine agonists or levodopa. In the real world of maintenance of patients with PD, effects of safinamide application resemble therapy with classical monoamine oxidase inhibitors or amantadine in combination with other dopamine-substituting drugs. Safinamide is becoming increasingly available in the EU despite complex approval and pricing scenarios.