1-Benzyl-1,2,3,4-tetrahydro-β-carboline as channel blocker of N-methyl-D-aspartate receptors

Preliminary study to identify CXCR4 inhibitors as potential therapeutic agents for Alzheimer's and Parkinson's diseases

Neurodegenerative disorders (NDDs) are known to exhibit genetic overlap and shared pathophysiology. This study aims to find the shared genetic architecture of Alzheimer's disease (AD) and Parkinson's disease (PD), two major age-related progressive neurodegenerative disorders. The gene expression profiles of GSE67333 (containing samples from AD patients) and GSE114517 (containing samples from PD patients) were retrieved from the Gene Expression Omnibus (GEO) functional genomics database managed by the National Center for Biotechnology Information. The web application GREIN (GEO RNA-seq Experiments Interactive Navigator) was used to identify differentially expressed genes (DEGs). A total of 617 DEGs (239 upregulated and 379 downregulated) were identified from the GSE67333 dataset. Likewise, 723 DEGs (378 upregulated and 344 downregulated) were identified from the GSE114517 dataset. The protein-protein interaction networks of the DEGs were constructed, and the top 50 hub genes were identified from the network of the respective dataset. Of the four common hub genes between two datasets, C-X-C chemokine receptor type 4 (CXCR4) was selected due to its gene expression signature profile and the same direction of differential expression between the two datasets. Mavorixafor was chosen as the reference drug due to its known inhibitory activity against CXCR4 and its ability to cross the blood-brain barrier. Molecular docking and molecular dynamics simulation of 51 molecules having structural similarity with Mavorixafor was performed to find two novel molecules, ZINC49067615 and ZINC103242147. This preliminary study might help predict molecular targets and diagnostic markers for treating Alzheimer's and Parkinson's diseases. Insight Box Our research substantiates the therapeutic relevance of CXCR4 inhibitors for the treatment of Alzheimer's and Parkinson's diseases. We would like to disclose the following insights about this study. We found common signatures between Alzheimer's and Parkinson's diseases at transcriptional levels by analyzing mRNA sequencing data. These signatures were used to identify putative therapeutic agents for these diseases through computational analysis. Thus, we proposed two novel compounds, ZINC49067615 and ZINC103242147, that were stable, showed a strong affinity with CXCR4, and exhibited good pharmacokinetic properties. The interaction of these compounds with major residues of CXCR4 has also been described.

A review of synthetic bioactive tetrahydro-β-carbolines: A medicinal chemistry perspective

1, 2, 3, 4-Tetrahydro-β-carboline (THβC) scaffold is widespread in many natural products (NPs) and synthetic compounds which show a variety of pharmacological activities. In this article, we reviewed the design, structures and biological characteristics of reported synthetic THβC compounds, and structure and activity relationship (SAR) of them were also discussed. This work might provide a reference for subsequent drug development based on THβC.

Advances in Applying Computer-Aided Drug Design for Neurodegenerative Diseases

Neurodegenerative diseases (NDs) including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease are incurable and affect millions of people worldwide. The development of treatments for this unmet clinical need is a major global research challenge. Computer-aided drug design (CADD) methods minimize the huge number of ligands that could be screened in biological assays, reducing the cost, time, and effort required to develop new drugs. In this review, we provide an introduction to CADD and examine the progress in applying CADD and other molecular docking studies to NDs. We provide an updated overview of potential therapeutic targets for various NDs and discuss some of the advantages and disadvantages of these tools.

β-Carboline as a Privileged Scaffold for Multitarget Strategies in Alzheimer's Disease Therapy

The natural β-carboline alkaloids display similarities with neurotransmitters that can be favorably exploited to design bioactive and bioavailable drugs for Alzheimer's disease (AD) therapy. Several AD targets are currently and intensively being investigated, divided in different hypotheses: mainly the cholinergic, the amyloid β (Aβ), and the Tau hypotheses. To date, only symptomatic treatments are available involving acetylcholinesterase and NMDA inhibitors. On the basis of plethoric single-target structure-activity relationship studies, the β-carboline scaffold was identified as a powerful tool for fostering activity and molecular interactions with a wide range of AD-related targets. This knowledge can undoubtedly be used to design multitarget-directed ligands, a highly relevant strategy preferred in the context of multifactorial pathology with intricate etiology such as AD. In this review, we first individually discuss the AD targets of the β-carbolines, and then we focus on the multitarget strategies dedicated to the deliberate design of new efficient scaffolds.

Neuropharmacological potentials of β-carboline alkaloids for neuropsychiatric disorders

Neuropsychiatric disorders are diseases of the central nervous system (CNS) which are characterised by complex pathomechanisms that including homeostatic failure, malfunction, atrophy, pathology remodelling and reactivity anomaly of the neuronal system where treatment options remain challenging. β-Carboline (βC) alkaloids are scaffolds of structurally diverse tricyclic pyrido[3,4-b]indole alkaloid with vast occurrence in nature. Their unique structural features which favour interactions with enzymes and protein receptor targets account for their potent neuropharmacological properties. However, our current understanding of their biological mechanisms for these beneficial effects, especially for neuropsychiatric disorders is sparse. Therefore, we present a comprehensive review of the scientific progress in the last two decades on the prospective pharmacology and physiology of the βC alkaloids in the treatment of some neuropsychiatric conditions such as depression, anxiety, Alzheimer's disease, Parkinson's disease, brain tumour, essential tremor, epilepsy and seizure, licking behaviour, dystonia, agnosia, spasm, positive ingestive response as demonstrated in non-clinical models. The current evidence supports that βC alkaloids offer potential therapeutic agents against most of these disorders and amenable for further drug design.

Elucidating Critical Proteinopathic Mechanisms and Potential Drug Targets in Neurodegeneration

Neurodegeneration entails progressive loss of neuronal structure as well as function leading to cognitive failure, apathy, anxiety, irregular body movements, mood swing and ageing. Proteomic dysregulation is considered the key factor for neurodegeneration. Mechanisms involving deregulated processing of proteins such as amyloid beta (Aβ) oligomerization; tau hyperphosphorylation, prion misfolding; α-synuclein accumulation/lewy body formation, chaperone deregulation, acetylcholine depletion, adenosine 2A (A2A) receptor hyperactivation, secretase deregulation, leucine-rich repeat kinase 2 (LRRK2) mutation and mitochondrial proteinopathies have deeper implications in neurodegenerative disorders. Better understanding of such pathological mechanisms is pivotal for exploring crucial drug targets. Herein, we provide a comprehensive outlook about the diverse proteomic irregularities in Alzheimer's, Parkinson's and Creutzfeldt Jakob disease (CJD). We explicate the role of key neuroproteomic drug targets notably Aβ, tau, alpha synuclein, prions, secretases, acetylcholinesterase (AchE), LRRK2, molecular chaperones, A2A receptors, muscarinic acetylcholine receptors (mAchR), N-methyl-D-aspartate receptor (NMDAR), glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs) and mitochondrial/oxidative stress-related proteins for combating neurodegeneration and associated cognitive and motor impairment. Cross talk between amyloidopathy, synucleinopathy, tauopathy and several other proteinopathies pinpoints the need to develop safe therapeutics with ability to strike multiple targets in the aetiology of the neurodegenerative disorders. Therapeutics like microtubule stabilisers, chaperones, kinase inhibitors, anti-aggregation agents and antibodies could serve promising regimens for treating neurodegeneration. However, drugs should be target specific, safe and able to penetrate blood-brain barrier.

Current Therapeutic Molecules and Targets in Neurodegenerative Diseases Based on in silico Drug Design

Abstract: Background

As the number of elderly persons increases, neurodegenerative diseases are becoming ubiquitous. There is currently a great need for knowledge concerning management of old-age neurodegenerative diseases; the most important of which are: Alzheimer’s disease, Parkinson’s disease, Amyotrophic Lateral Sclerosis, and Huntington’s disease.

Objective

To summarize the potential of computationally predicted molecules and targets against neurodegenerative diseases.

Method

Review of literature published since 1997 against neurodegenerative diseases, utilizing as keywords: in silico, Alzheimer’s disease, Parkinson’s disease, Amyotrophic Lateral Sclerosis ALS, and Huntington’s disease was conducted.

Results and Conclusion

Due to the costs associated with experimentation and current ethical law, performing experiments directly on living organisms has become much more difficult. In this scenario, in silico techniques have been successful and have become powerful tools in the search to cure disease. Researchers use the Computer Aided Drug Design pipeline which: 1) generates 3-dimensional structures of target proteins through homology modeling 2) achieves stabilization through molecular dynamics simulation, and 3) exploits molecular docking through large compound libraries. Next generation sequencing is continually producing enormous amounts of raw sequence data while neuroimaging is producing a multitude of raw image data. To solve such pressing problems, these new tools and algorithms are required. This review elaborates precise in silico tools and techniques for drug targets, active molecules, and molecular docking studies, together with future prospects and challenges concerning possible breakthroughs in Alzheimer’s, Parkinson’s, Amyotrophic Lateral Sclerosis, and Huntington’s disease.

Emerging Synaptic Molecules as Candidates in the Etiology of Neurological Disorders

Synapses are complex structures that allow communication between neurons in the central nervous system. Studies conducted in vertebrate and invertebrate models have contributed to the knowledge of the function of synaptic proteins. The functional synapse requires numerous protein complexes with specialized functions that are regulated in space and time to allow synaptic plasticity. However, their interplay during neuronal development, learning, and memory is poorly understood. Accumulating evidence links synapse proteins to neurodevelopmental, neuropsychiatric, and neurodegenerative diseases. In this review, we describe the way in which several proteins that participate in cell adhesion, scaffolding, exocytosis, and neurotransmitter reception from presynaptic and postsynaptic compartments, mainly from excitatory synapses, have been associated with several synaptopathies, and we relate their functions to the disease phenotype.

Synthesis and application of β-carbolines as novel multi-functional anti-Alzheimer's disease agents

The design, synthesis and assessment of β-carboline core-based compounds as potential multifunctional agents against several processes that are believed to play a significant role in Alzheimer's disease (AD) pathology, are described. The activity of the compounds was determined in Aβ self-assembly (fibril and oligomer formation) and cholinesterase (AChE, BuChE) activity inhibition, and their antioxidant properties were also assessed. To obtain insight into the mode of action of the compounds, HR-MS studies were carried out on the inhibitor-Aβ complex formation and molecular docking was performed on inhibitor-BuChE interactions. While several compounds exhibited strong activities in individual assays, compound 14 emerged as a promising multi-target lead for the further structure-activity relationship studies.

Current pharmacotherapy and putative disease-modifying therapy for Alzheimer's disease

Alzheimer's disease (AD) is an age-related neurodegenerative disease of the central nervous system correlated with the progressive loss of cognition and memory. β-Amyloid plaques, neurofibrillary tangles and the deficiency in cholinergic neurotransmission constitute the major hallmarks of the AD. Two major hypotheses have been implicated in the pathogenesis of AD namely the cholinergic hypothesis which ascribed the clinical features of dementia to the deficit cholinergic neurotransmission and the amyloid cascade hypothesis which emphasized on the deposition of insoluble peptides formed due to the faulty cleavage of the amyloid precursor protein. Current pharmacotherapy includes mainly the acetylcholinesterase inhibitors and N-methyl-D-aspartate receptor agonist which offer symptomatic therapy and does not address the underlying cause of the disease. The disease-modifying therapy has garnered a lot of research interest for the development of effective pharmacotherapy for AD. β and γ-Secretase constitute attractive targets that are focussed in the disease-modifying approach. Potentiation of α-secretase also seems to be a promising approach towards the development of an effective anti-Alzheimer therapy. Additionally, the ameliorative agents that prevent aggregation of amyloid peptide and also the ones that modulate inflammation and oxidative damage associated with the disease are focussed upon. Development in the area of the vaccines is in progress to combat the characteristic hallmarks of the disease. Use of cholesterol-lowering agents also is a fruitful strategy for the alleviation of the disease as a close association between the cholesterol and AD has been cited. The present review underlines the major therapeutic strategies for AD with focus on the new developments that are on their way to amend the current therapeutic scenario of the disease.

Current and novel therapeutic molecules and targets in Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder in which the death of brain cells causes memory loss and cognitive decline, i.e., dementia. The disease starts with mild symptoms and gradually becomes severe. AD is one of the leading causes of mortality worldwide. Several different hallmarks of the disease have been reported such as deposits of β-amyloid around neurons, hyperphosphorylated tau protein, oxidative stress, dyshomeostasis of bio-metals, low levels of acetylcholine, etc. AD is not simple to diagnose since there is no single diagnostic test for it. Pharmacotherapy for AD currently provides only symptomatic relief and mostly targets cognitive revival. Computational biology approaches have proved to be reliable tools for the selection of novel targets and therapeutic ligands. Molecular docking is a key tool in computer-assisted drug design and development. Docking has been utilized to perform virtual screening on large libraries of compounds, and propose structural hypotheses of how the ligands bind with the target with lead optimization. Another potential application of docking is optimization stages of the drug-discovery cycle. This review summarizes the known drug targets of AD, in vivo active agents against AD, state-of-the-art docking studies done in AD, and future prospects of the docking with particular emphasis on AD.

Dysfunctional synapse in Alzheimer's disease - A focus on NMDA receptors

Alzheimer's disease (AD) is the most prevalent form of dementia in the elderly. Alterations capable of causing brain circuitry dysfunctions in AD may take several years to develop. Oligomeric amyloid-beta peptide (Aβ) plays a complex role in the molecular events that lead to progressive loss of function and eventually to neurodegeneration in this devastating disease. Moreover, N-methyl-D-aspartate (NMDA) receptors (NMDARs) activation has been recently implicated in AD-related synaptic dysfunction. Thus, in this review we focus on glutamatergic neurotransmission impairment and the changes in NMDAR regulation in AD, following the description on the role and location of NMDARs at pre- and post-synaptic sites under physiological conditions. In addition, considering that there is currently no effective ways to cure AD or stop its progression, we further discuss the relevance of NMDARs antagonists to prevent AD symptomatology. This review posits additional information on the role played by Aβ in AD and the importance of targeting the tripartite glutamatergic synapse in early asymptomatic and possible reversible stages of the disease through preventive and/or disease-modifying therapeutic strategies. This article is part of the Special Issue entitled 'The Synaptic Basis of Neurodegenerative Disorders'.