Central Nervous System Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry - Central Nervous System Agents) - Volume 18, Issue 2, 2018

Background: Epilepsy is one in every of the foremost important chronic neurological disorders with high incidence worldwide. Several epileptic patients don't seem to be fully treated with currently available marketed medicines likewise so many drugs have shown unfavorable side effect and drug interaction. Therefore, there are continuing interests to seek out new anticonvulsant drugs. Methods: Literature search was carried out to indentify isatin containing derivatives as anticonvulsant drugs. Results: Common synthetic schemes were studied to design and develop isatin derives anticonvulsant agents. Various structural features essential for the design of isatin compounds were reported. Anticonvulsant activity is evaluated by different tests were identified and their results can be considered for the design of novel isatin derivatives as anticonvulsants. Conclusion: In outline, isatin has been proved to be an excellent hybrid building the molecule with interesting biological activities. Among the prospect of derivatizing the N1, C2 and C3 positions, along with substitution on the aromatic ring, the synthetic modification for isatin is almost endless. Despite the fact that isatin derivatives are well-studied compounds, new derivatives are continually being discovered on the basis of known AEDs, isatin has been fused with other bioactive drug fragments and subsequently investigated as hybrid/dual action drugs and selectively targeted against convulsion.

Introduction: Several recent developments in melatonin research deserve attention and divulgation. The role of melatonin in the brain has been extended to its synthesis in the cerebellum as a response to inflammation, findings that exceed the earlier demonstration of aralkylamine Nacetyltransferase expression. The release of melatonin via the pineal recess into the third ventricle appears to be more important than previously believed and has been discussed as a strong direct signal to the suprachiasmatic nucleus. The mitochondrial role of melatonin has been substantially extended by the demonstration of the melatonin receptor MT1 in this organelle and evidence for melatonin synthesis in mammalian mitochondria, in addition to the previously shown uptake into these organelles. Contrary to rats and mice, melatonin can act in a prodiabetic way, especially under conditions of MT2 overexpression, an effect that leads to reduced insulin secretion. These findings are discussed in the context of brain insulin resistance as an early change in low-grade neuroinflammation, however, with emphasis to the distinction between reduced insulin and insulin resistance. Various new data underline the stimulation of sirtuins 1 and 3 by melatonin in the context of aging and of inflammation. Data support a nexus between sirtuins, circadian oscillators and melatonin, and hints for the transduction of melatonin effects by sirtuin 1. Further transduction mechanisms concern the upregulation of microRNAs as well as their transmission via exosomes. Conclusion: The recent findings on melatonin have also to be seen in their consequences to the use of synthetic melatonergic agonists.

Introduction: The efficacy of L-dopa in the treatment of Parkinson's disease depends on its metabolic conversion to dopamine in the brain, however extensive peripheral metabolism of L-dopa diminishes its availability for uptake into the brain. L-Dopa is extensively decarboxylated in the gastrointestinal tract and peripheral tissues by Aromatic L-Amino Acid Decarboxylase (AADC), and AADC inhibitors are thus frequently combined with L-dopa therapy. When AADC is inhibited, 3-Omethylation Catalysed by Catechol-O-Methyltransferase (COMT) becomes a dominant metabolic pathway for L-dopa, and COMT inhibitors may thus also be used as adjuncts to L-dopa in Parkinson's disease. Monoamine Oxidase (MAO), in turn, metabolises dopamine in the brain, and MAO-B inhibitors may exert a dopamine sparing effect in the brain. Materials & Methods: Based on the roles of COMT and MAO in the metabolism of L-dopa and dopamine, the present study attempts to discover novel dual inhibitors of these enzymes. For this purpose, nitrocatechol derivatives of chalcone were synthesised and evaluated as inhibitors of COMT and MAO. The chalcone class of compounds is well known to potently inhibit MAO-B, while nitrocatechol derivatives (e.g. tolcapone and entacapone) are clinically used COMT inhibitors. Results: The results document that all of the derivatives are high potency in vitro inhibitors of rat liver COMT with IC50 values ranging from 0.07 to 0.29 μM. Under these experimental conditions, tolcapone and entacapone display IC50 values of 0.26 μM and 0.25 μM, respectively. The chalcones are less potent as inhibitors of MAO with the most potent inhibitor possessing a Ki of 4.6 μM for the in vitro inhibition of human MAO-B. Conclusion: This study shows that nitrocatechol derivatives of chalcone may act as COMT and MAO-B inhibitors, and proposes a general strategy for further enhancing MAO-B inhibition while retaining the potent COMT inhibition activity of this class.

Introduction: Parkinson's disease is affecting millions of people worldwide. The prevalence of Parkinson's disease is 0.3% globally, rising to 1% in more than 60 years of age and 4% in more than 80 years of age and the figures are thought to be doubled by 2030. Thus, there is a great need to identify novel therapeutic strategies or candidate drug molecule which can rescue neuronal degeneration. β -asarone has the potential to act as a neuroprotective agent but regarding its role in Parkinson's disease, very few reports are available. Thus, this study was undertaken to unlock the potential of β-asarone against Parkinson's disease. Material and Methods: The Absorption, Distribution, Metabolism, and Excretion (ADME) analysis has been done by using Swiss ADME Predictor. The interactions of β-asarone with dopaminergic receptors were investigated by Glide Program 5.0. The crystal structures of dopamine receptors were retrieved from Research Collaboratory for Structural Bioinformatics- Protein Data Bank (RCSB-PDB). The structure of β-asarone was drawn in Chem Draw Ultra 7.0.1. Finally, the toxicity of β-asarone has been predicted by using online web-servers like Lazar and Protox. Results and Discussion: The ADME data of current investigation has shown good oral bioavailability of β-asarone. It also showed a good binding affinity towards dopaminergic receptors. Further, it was found to be interacting through hydrogen bond with different amino acid residues of D2 and D3 receptors. However, β-asarone was predicted to be toxic in various species of rodents, as per the results of toxicity online web servers. Conclusion: Based on the current finding from ADME and docking studies, these preliminary results may act as effective precursor tool for the development of β-asarone as a promising anti-Parkinson agent. However, furthermore experimental validation using in-vitro & in-vivo studies is needed to explore their therapeutic andtoxic effects.

Background: Chalcone has been identified as a promising lead for the design of Monoamine Oxidase (MAO) inhibitors. This study attempted to discover potent and selective chalcone-derived MAO inhibitors by synthesising a series consisting of various cyclic chalcone derivatives. The cyclic chalcones were selected based on the possibility that their restricted structures would confer a higher degree of MAO isoform selectivity, and included the following chemical classes: 1-indanone, 1- tetralone, 1-benzosuberone, chromone, thiochromone, 4-chromanone and 4-thiochromanone. Methods: The cyclic chalcone derivatives were synthesised via a one-pot Claisen-Schmidt condensation reaction. The MAO inhibitory properties of the chalcone derivatives were evaluated with the recombinant human MAO-A and MAO-B enzymes and the potencies were expressed as the IC50 values. A selected inhibitor was docked into an active site model of MAO-B. Results: The results showed that the cyclic chalcones are in general good potency, and in most instances specific inhibitors of the MAO-B isoform. Among these compounds, the 4-chromanone derivative was the most potent MAO-B inhibitor with an IC50 value of 0.156 μM. To further investigate the MAO inhibition of cyclic chalcones, a series of twenty-three 2-benzylidene-1-tetralone derivatives were synthesised and evaluated as MAO inhibitors. Most 2-benzylidene-1-tetralones possess good inhibitory activity and specificity for MAO-B with the most potent inhibitor displaying an IC50 value of 0.0064 μM, while the most potent MAO-A inhibitor possessed an IC50 value of 0.754 μM. Conclusion: This study thus shows that certain cyclic chalcones are human MAO-B inhibitors, compounds that could be suitable for the treatment of neurodegenerative disorders such as Parkinson's disease.

Background: Glycogen synthase kinase-3β plays a significant role in the regulation of various pathological pathways relating to the Central Nervous System (CNS). Dysregulation of Glycogen synthase kinase 3 (GSK-3) activity gives rise to numerous neuroinflammation and neurodegenerative related disorders that affect the whole central nervous system. Objective: By the sequential application of in-silico tools, efforts have been attempted to design the novel GSK-3β inhibitors. Method: Owing to the potential role of GSK-3β in nervous disorders, we have attempted to develop the quantitative four featured pharmacophore model comprising two Hydrogen Bond Acceptors (HBA), one Ring Aromatic (RA), and one Hydrophobe (HY), which were further affirmed by costfunction analysis, rm2 matrices, internal and external test set validation and Guner-Henry (GH) scoring analysis. Validated pharmacophoric model was used for virtual screening and out of 345 compounds, two potential virtual hits were finalized that were on the basis of fit value, estimated activity and Lipinski's violation. The chosen compounds were subjected to dock within the active site of GSK-3β. Result: Four essential features, i.e., two Hydrogen Bond Acceptors (HBA), one Ring Aromatic (RA), and one Hydrophobe (HY), were subjected to build the pharmacophoric model and showed good correlation coefficient, RMSD and cost difference values of 0.91, 0.94 and 42.9 respectively and further model was validated employing cost-function analysis, rm2-matrices, internal and external test set prediction with r2 value of 0.77 and 0.84. Docked conformations showed potential interactions in between the features of the identified hits (NCI 4296, NCI 3034) and the amino acids present in the active site. Conclusion: In line with the overhead discussion, and through our stepwise computational approaches, we have identified novel, structurally diverse glycogen synthase kinase inhibitors.