A novel selective MAO-B inhibitor with neuroprotective and anti-Parkinsonian properties

Novel and experimental therapeutics for the management of motor and non-motor Parkinsonian symptoms

BACKGROUND  : Both motor and non-motor symptoms of Parkinson's disease (PD) have a substantial detrimental influence on the patient's quality of life. The most effective treatment remains oral levodopa. All currently known treatments just address the symptoms; they do not completely reverse the condition.

METHODOLOGY

In order to find literature on the creation of novel treatment agents and their efficacy for PD patients, we searched PubMed, Google Scholar, and other online libraries.

RESULTS

According to the most recent study on Parkinson's disease (PD), a great deal of work has been done in both the clinical and laboratory domains, and some current scientists have even been successful in developing novel therapies for PD patients.

CONCLUSION

The quality of life for PD patients has increased as a result of recent research, and numerous innovative medications are being developed for PD therapy. In the near future, we will see positive outcomes regarding PD treatment.

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.

Design, synthesis and biological evaluation of novel indanones derivatives as potent acetylcholinesterase/monoamine oxidase B inhibitors

Aim: Based on a multitarget design strategy, a series of novel indanone-1-benzyl-1,2,3,6-tetrahydropyridin hybrids were identified for the potential treatment of Alzheimer's disease (AD). Results: These compounds exhibited significant inhibitory activities against acetylcholinesterase (AChE) and moderate inhibitory activities toward monoamine oxidase B (MAO-B). The optimal compound A1 possessed excellent dual AChE/MAO-B inhibition both in terms of potency (AChE: IC50 = 0.054 ± 0.004 μM; MAO-B: IC50 = 3.25 ± 0.20 μM), moderate inhibitory effects on self-mediated amyloid-β (Aβ) aggregation and antioxidant activity. In addition, compound A1 exhibited low neurotoxicity. More importantly, compound A1 showed significant cognitive and spatial memory improvements in the scopolamine-induced AD mouse model. Conclusion: All results suggest that compound A1 may become a promising lead of anti-AD drug for further development.

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.

Dietary supplementation of Acanthopanax senticosus extract alleviates motor deficits in MPTP-induced Parkinson's disease mice and its underlying mechanism

Acanthopanax senticosus extract (ASE), a dietary supplement with antifatigue, neuroprotective, and immunomodulatory properties, has been widely used due to its high polyphenol content. Our previous study showed that ASE could be used to treat Parkinson's disease (PD) as it contains multiple monoamine oxidase B inhibitors prescribed in early PD. However, its mechanism remains ambiguous. In this study, we investigated the protective effects of ASE on MPTP-induced PD in mice and explored the underlying mechanisms of action. We found that the administration of ASE significantly improved motor coordination in mice with MPTP-induced PD. As shown by quantitative proteomic analysis, 128 proteins' expression significantly changed in response to ASE administration, most of which were involved with Fcγ receptor-mediated phagocytosis in macrophages and monocytes signaling pathway, PI3K/AKT signaling pathway, and insulin receptor signaling pathway. Furthermore, the network analysis results showed that ASE modulates protein networks involved in regulating cellular assembly, lipid metabolism, and morphogenesis, all of which have implications for treating PD. Overall, ASE served as a potential therapeutic because it regulated multiple targets to improve motor deficits, which could lay the strong foundation for developing anti-PD dietary supplements.

Glycolysis: The Next Big Breakthrough in Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disease characterized by the death of dopaminergic neurons. Its pathogenesis comprises defects in the physiological pathway of mitophagy and mutations in the genes involved in this process's regulatory mechanism. PD manifests itself with multiple motor and non-motor symptoms, and currently, there are multiple pharmacological treatments, and unconventional non-drug treatments available. The mainstay of Parkinson's disease treatment has centered around directly manipulating neural mechanisms to retain high dopamine levels, either by exogenous administration, increasing intrinsic production, or inhibiting the breakdown of dopamine. In this review, we highlight a new potential biochemical modality of treatment, treating PD through glycolysis. We highlight how terazosin (TZ), via PGK1, increases ATP levels and how enhanced glycolysis serves a neuroprotective role in PD, and compensates for damage caused by mitophagy. We also discuss the role of quercetin, a bioactive flavonoid, in preventing the development of PD, and reversing mitochondrial dysfunction but only so in diabetic patients. Thus, further research should be conducted on glycolysis as a protective target in PD that can serve to not just prevent, but also alleviate the non-dopaminergic signs and symptoms of PD.

Detection of monoamine oxidase B using dark-field light scattering imaging and colorimetry

Detection of MAO-B using dark-field light scattering imaging and colorimetry based on localized surface plasmon resonance induced by silver deposited gold nanostars.

Dimeric Drugs

This review intends to summarize the structures of an extensive number of symmetrical-dimeric drugs, having two monomers linked via a bridging entity while emphasizing the large versatility of biologically active substances reported to possess dimeric structures. The largest number of classes of these compounds consist of anticancer agents, antibiotics/antimicrobials, and anti-AIDS drugs. Other symmetrical-dimeric drugs include antidiabetics, antidepressants, analgesics, anti-inflammatories, drugs for the treatment of Alzheimer's disease, anticholesterolemics, estrogenics, antioxidants, enzyme inhibitors, anti-Parkisonians, laxatives, antiallergy compounds, cannabinoids, etc. Most of the articles reviewed do not compare the activity/potency of the dimers to that of their corresponding monomers. Only in limited cases, various suggestions have been made to justify unexpected higher activity of the dimers vs. the corresponding monomers. These suggestions include statistical effects, the presence of dimeric receptors, binding of a dimer to two receptors simultaneously, and others. It is virtually impossible to predict which dimers will be preferable to their respective monomers, or which linking bridges will lead to the most active compounds. It is expected that the extensive number of articles summarized, and the large variety of substances mentioned, which display various biological activities, should be of interest to many academic and industrial medicinal chemists.

Research on developing drugs for Parkinson's disease

Current treatments for Parkinson's disease (PD) are mainly dopaminergic drugs. However, dopaminergic drugs are only symptomatic treatments and limited by several side effects. Recent studies into drug development focused on emerging new molecular mechanisms, including nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, nuclear receptor-related 1 (Nurr1), adenosine receptor A2, nicotine receptor, metabotropic glutamate receptors (mGluRs), and glucocerebrosidase (GCase). Also, immunotherapy and common pathological mechanisms shared with Alzheimer's Disease (AD) and diabetes have attracted much attention. In this review, we summarized the development of preclinical and clinical studies of novel drugs and the improvement of dopaminergic drugs to provide a prospect for PD treatment.

Glial cells in Parkinson´s disease: protective or deleterious?

Glial cells have been identified more than 100 years ago, and are known to play a key role in the central nervous system (CNS) function. A recent piece of evidence is emerging showing that in addition to the capacity of CNS modulation and homeostasis, glial cells are also being looked like as a promising cell source not only to study CNS pathologies initiation and progression but also to the establishment and development of new therapeutic strategies. Thus, in the present review, we will discuss the current evidence regarding glial cells' contribution to neurodegenerative diseases as Parkinson's disease, providing cellular, molecular, functional, and behavioral data supporting its active role in disease initiation, progression, and treatment. As so, considering their functional relevance, glial cells may be important to the understanding of the underlying mechanisms regarding neuronal-glial networks in neurodegeneration/regeneration processes, which may open new research opportunities for their future use as a target or treatment in human clinical trials.

Exploring the Therapeutic Potentials of Highly Selective Oxygenated Chalcone Based MAO-B Inhibitors in a Haloperidol-Induced Murine Model of Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder of dopaminergic, noradrenergic, and serotonergic systems, in which dopamine, noradrenaline, and serotonin levels are depleted and lead to the development of motor and non-motor symptoms such as tremor, bradykinesia, weight changes, fatigue, depression, and visual hallucinations. Therapeutic strategies place much focus on dopamine replacement and the inhibition of dopamine metabolism. The present study was based on the known abilities of chalcones to act as molecular scaffolds that selectively inhibit MAO-B with the added advantage of binding reversibly. Recently, we synthesized a series of 26 chalcone compounds, amongst which (2E)-1-(2H-1,3-benzodioxol-5-yl)-3-(4-fluorophenyl)prop-2-en-1-one (O10) and (2E)-1-(2,3-dihydro-1,4-benzodioxin-6-yl)-3-(4-fluorophenyl)prop-2-en-1-one (O23) most inhibited MAO-B. Hence, the present study was performed to explore the molecular mechanisms responsible for the neuroprotective effect of O10 and O23 at varying doses such as 10, 20, and 30 mg/kg each in a haloperidol-induced murine model of PD. Both compounds were effective (though O23 was the more effective) at ameliorating extrapyramidal and non-motor symptoms in the model and improved locomotory and exploratory behaviors, reduced oxidative stress markers, and enhanced antioxidant marker and neurotransmitter levels. Furthermore, histopathological studies showed O10 and O23 both reduced neurofibrillary tangles and plaques to almost normal control levels.

Development of methylthiosemicarbazones as new reversible monoamine oxidase-B inhibitors for the treatment of Parkinson's disease

Selective monoamine oxidase-B (MAO-B) inhibition is an attractive subject for the treatment of Parkinson's disease (PD). In the current study, we synthesized some selected derivatives of methylthiosemicarbazones and investigated their MAOs and acetylcholinesterase (AChE) inhibitory activities. Among the series synthesized, compounds SM5, SM4, and SM9 most inhibited MAO-B with IC₅₀ values of 5.48, 7.06, and 8.03 µM, respectively. All compounds tested weakly inhibited MAO-A at 10 µM with the residual activities of >50%. Compound SM5 had the highest selectivity index (SI) value for MAO-B (>7.30), followed by SM4 (>5.67). Kinetic experiments revealed that SM5 competitively inhibited MAO-B, with a mean K_i value of 2.39 ± 0.15 µM. Reversibility experiments showed that SM5 reversibly inhibited MAO-B, and 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assays revealed that SM5 was not toxic to Vero cells (IC₅₀ = 198.96 µg/mL). The SM5/MAO-B interaction was ascertained by molecular docking and dynamics studies. The study shows that SM5 competitively inhibits MAO-B in a reversible, moderate selective manner, and that it is non-toxic to Vero cells.Communicated by Ramaswamy H. Sarma.

Chemical characterization of small-molecule inhibitors of monoamine oxidase B synthesized from the Acanthopanax senticosus root with affinity ultrafiltration mass spectrometry

RATIONALE

Discovering and identifying new small-molecule inhibitors of monoamine oxidase B (MAO-B) could provide the potential to treat many neurodegenerative diseases.

METHODS

We employed affinity ultrafiltration liquid chromatography/tandem mass spectrometry (AUF-LC/MSⁿ ) to identify and characterize small-molecule inhibitors of MAO-B from a 30% ethanolic extract of Acanthopanax senticosus root (ASR). In vitro tests were performed in stimulated BV2 microglia to evaluate the anti-inflammatory effects of the ASR preparation. An in vitro enzyme activity assay, measuring half-maximal inhibitory concentrations (IC₅₀ ) against MAO-B, determined the inhibitory activity of the potential MAO-B ligands.

RESULTS

ASR treatment significantly inhibited NO release (p <0.01) and attenuated tumor necrosis factor (TNF)-α expression in stimulated BV2 microglia. Nine compounds were isolated from the ASR preparation as potential MAO-B inhibitors, identified as quinic acid, chlorogenic acid, isofraxidin, dicaffeoylquinic acid, pinoresinol diglucoside, medioresinol 4'-O-β-D-glucopyranoside, eletutheroside E, syringaresinol O-β-D-glucoside, and trihydroxyoctadecenoic acid, based on their tandem mass spectra.

CONCLUSIONS

Our study provides critical data on compounds from ASR extracts which are suitable for the development of new MAO-B inhibitors as potential therapeutics for neurodegenerative diseases.

New role for crinamine as a potent, safe and selective inhibitor of human monoamine oxidase B: In vitro and in silico pharmacology and modeling

ETHNOPHARMACOLOGICAL RELEVANCE

The development of selective inhibitors of monoamine oxidase B (MAO-B) has been essential in treating Parkinson's disease. However, the apparent hepatotoxicity and drug-drug interactions of current inhibitors accentuate the need for the development of novel pharmacotherapies. Crossyne guttata (L.) D. & U. Müll-Doblies is used frequently by Rastafarian bush doctors to treat alcoholism, a disorder which is also accentuated by MAO.

OBJECTIVE

The study sought to isolate, identify and characterise the biologically active constituents of C. guttata based on their ability to inhibit the MAO enzymes.

MATERIALS AND METHODS

Column chromatography was used to isolate the biologically active alkaloids of C. guttata. The ability of the alkaloids to inhibit the biotransformation of 4-aminoantipyrine by the MAO enzymes was evaluated in vitro. In silico docking was conducted using AutoDock Vina server while the pharmacokinetic properties of the compounds were evaluated using SwissADME.

RESULTS

Chromatographic separation of an ethanolic fraction of C. guttata yielded the alkaloids crinamine 1 and epibuphanisine 2. 1 and 2 along with structurally related alkaloids haemanthamine 3 and haemanthidine 4 were evaluated for their ability to inhibit the action of isozymes of MAO in vitro. Alkaloids effected submicromolar IC₅₀ values against MAO-B, the most potent of which being crinamine 1 (0.014 μM) > haemanthidine 4 (0.017 μM) > epibuphanisine 2 (0.039 μM) > haemanthamine 3 (0.112 μM). Binding energies of the alkaloids correlated well with their inhibitory potential with crinamine displaying the best binding efficacy and binding energy score with MAO-B.

DISCUSSION AND CONCLUSION

Crinamine and epibuphanisine exhibited potent and selective inhibitory activity towards MAO-B. After comprehensive in silico investigations encompassing robust molecular docking analysis, the drug-like attributes and safety of the alkaloids suggest the crinamine is a potentially safe drug for human application.

Novel approaches to the discovery of selective human monoamine oxidase-B inhibitors: is there room for improvement?

Introduction: Selective monoamine oxidase-B (MAO-B) inhibitors are currently used as coadjuvants for the treatment of early motor symptoms in Parkinson's disease. They can, based on their chemical structure and mechanism of inhibition, be categorized into reversible and irreversible agents. Areas covered: This review provides a comprehensive update on the development state of selective MAO-B inhibitors describing the results, structures, structure-activity relationships (SARs) and Medicinal chemistry strategies as well as the related shortcomings over the past five years. Expert opinion: Researchers have explored and implemented new and old chemical scaffolds achieving high inhibitory potencies and isoform selectivity. Most of them were characterized and proposed as multitarget agents able to act at different levels (including AChE inhibition, H3R or A_2AR antagonism, antioxidant and chelating properties, Aβ_1-42 aggregation reduction) in the network of aetiologies of neurodegenerative disorders. These results can also be used to avoid 'cheese-reaction' effects and the occurrence of serotonergic syndrome in patients.

Synthesis of potent neuroprotective butenolides based on plant smoke derived 3,4,5-Trimethylfuran-2(5H)-one and 3-methyl-2H-furo[2,3-c]pyrone-2-one

Smoke derived karrikinolide and trimethylbutenolide exerted neuroprotective effects against monoamine oxidase and acetylcholinesterase. Synthesis of potent analogs was achieved. Sulphur substitution in the bicyclic ring structure of KAR₁ displayed the most encouraging activity returning IC₅₀ values of 13.75 ± 0.001 μM and 0.03 ± 0.02 μM for monoamine oxidase A and B and 0.08 ± 0.006 μM for acetylcholinesterase. Neuroprotective butenolides may be particularly useful in the treatment of depressive disorders, Alzheimer's and Parkinson's diseases.

Propofol inhibits the voltage-gated sodium channel NaChBac at multiple sites

Voltage-gated sodium (NaV) channels are important targets of general anesthetics, including the intravenous anesthetic propofol. Electrophysiology studies on the prokaryotic NaV channel NaChBac have demonstrated that propofol promotes channel activation and accelerates activation-coupled inactivation, but the molecular mechanisms of these effects are unclear. Here, guided by computational docking and molecular dynamics simulations, we predict several propofol-binding sites in NaChBac. We then strategically place small fluorinated probes at these putative binding sites and experimentally quantify the interaction strengths with a fluorinated propofol analogue, 4-fluoropropofol. In vitro and in vivo measurements show that 4-fluoropropofol and propofol have similar effects on NaChBac function and nearly identical anesthetizing effects on tadpole mobility. Using quantitative analysis by 19F-NMR saturation transfer difference spectroscopy, we reveal strong intermolecular cross-relaxation rate constants between 4-fluoropropofol and four different regions of NaChBac, including the activation gate and selectivity filter in the pore, the voltage sensing domain, and the S4-S5 linker. Unlike volatile anesthetics, 4-fluoropropofol does not bind to the extracellular interface of the pore domain. Collectively, our results show that propofol inhibits NaChBac at multiple sites, likely with distinct modes of action. This study provides a molecular basis for understanding the net inhibitory action of propofol on NaV channels.