Synthesis, Biological Evaluation, and In Silico Studies of New Acetylcholinesterase Inhibitors Based on Quinoxaline Scaffold

Explore new quinoxaline pharmacophore tethered sulfonamide fragments as in vitro α-glucosidase, α-amylase, and acetylcholinesterase inhibitors with ADMET and molecular modeling simulation

A new series of quinoxaline-sulfonamide derivatives 3-12 were synthesized using fragment-based drug design by reaction of quinoxaline sulfonyl chloride (QSC) with different amines and hydrazines. The quinoxaline-sulfonamide derivatives were evaluated for antidiabetic and anti-Alzheimer's potential against α-glucosidase, α-amylase, and acetylcholinesterase enzymes. These derivatives showed good to moderate potency against α-amylase and α-glucosidase with inhibitory percentages between 24.34 ± 0.01%-63.09 ± 0.02% and 28.95 ± 0.04%-75.36 ± 0.01%, respectively. Surprisingly, bis-sulfonamide quinoxaline derivative 4 revealed the most potent activity with inhibitory percentages of 75.36 ± 0.01% and 63.09 ± 0.02% against α-glucosidase and α-amylase compared to acarbose (IP = 57.79 ± 0.01% and 67.33 ± 0.01%), respectively. Moreover, the quinoxaline derivative 3 exhibited potency as α-glucosidase and α-amylase inhibitory with a minute decline from compound 4 and acarbose with inhibitory percentages of 44.93 ± 0.01% and 38.95 ± 0.01%. Additionally, in vitro acetylcholinesterase inhibitory activity for designed derivatives exhibited weak to moderate activity. Still, sulfonamide-quinoxaline derivative 3 emerged as the most active member with inhibitory percentage of 41.92 ± 0.02% compared with donepezil (IP = 67.27 ± 0.60%). The DFT calculations, docking simulation, target prediction, and ADMET analysis were performed and discussed in detail.

Synthesis and evaluation of coumarin derivatives on antioxidative, tyrosinase inhibitory activities, melanogenesis, and in silico investigations

New coumarin derivatives were designed using a 2-(2-oxo-2H-chromen-4-yl)acetic acid scaffold conjugated with amino acid esters or tyramine. The anti-tyrosinase and anti-lipid peroxidation activities of the synthesized compounds were investigated. Coumarin derivatives 7,9, 11-13, 15-18 showed strong anti-lipid peroxidation activity. Compound 13 exhibited uncompetitive tyrosinase inhibitory activity with an IC50 value of 68.86 µM. Compound 14 (% activity = 123.41) showed stronger tyrosinase activating activity than 8-methoxypsolaren (8-MOP, % activity = 109.46). In silico studies revealed different poses between the inhibitors and activators near the tyrosinase catalytic site. Compounds 13 (25-50 μM) and 14 (25-100 μM) did not show cytotoxicity against B16F10 cells. In contrast to the tyrosinase inhibition assay, compound 13 (50 μM) suppressed melanogenesis in B16F10 cells with two times higher potency than KA (100 μM). Compound 14 at 100 μM showed melanogenesis enhancement in B16F10 cells in a dose-dependent manner, however, inferior to the 8-MOP. Based on the findings, compound 13 and 14 offer potential for development as skin-lightening agents and vitiligo therapy agents, respectively.

Green synthesis, biological and molecular docking of some novel sulfonamide thiadiazole derivatives as potential insecticidal against Spodoptera littoralis

Although crop plants provide the majority of human food, pests and insects frequently cause huge economic losses. In order to develop innovative insecticidal compounds with low toxicity and a positive environmental impact, we developed new N-(4-sulfamoylphenyl)-1,3,4-thiadiazole-2-carboxamide derivatives (2-12). With the use of spectroscopic techniques and elemental data, the chemical structure of these new compounds was meticulously clarified. The toxicological and biological effects of the synthesized compound of the cotton leafworm Spodoptera littoralis (Boisduval, 1833) under laboratory conditions were also investigated. Regarding the determined LC50 values, compounds 3, 7, 8, and 10 showed the most potent toxic effect with LC50 values of 29.60, 30.06, 27.65 and 29.01 ppm, respectively. A molecular docking investigation of twelve synthetic compounds (from compound 2 to compound 12) was performed against AChE (Acetylcholinesterase). There was a wide range of binding affinities shown by these compounds. This work suggests that these substances may have insecticidal and AChE inhibitory properties, and it may be possible to further explore them in the process of creating pesticides that target AChE.

Novel iodoquinazolinones bearing sulfonamide moiety as potential antioxidants and neuroprotectors

In a search for new antioxidants, a set of new iodoquinazolinone derivatives bearing benzenesulfonamide moiety and variable acetamide pharmacophores 5-17 were designed and synthesized. The structures of the synthesized compounds were confirmed based on spectral data. Compounds 5-17 were screened using in vitro assay for their antioxidant potential and acetylcholinesterase (AChE) inhibitory activity. The 2-(6-iodo-4-oxo-3-(4-sulfamoylphenyl)-3,4-dihydroquinazolin-2-ylthio)-N-(pyrazin-2-yl) acetamide 14 was the most active scaffold with potent AChE inhibitory activity. Compound 14 showed relative safety with a median lethal dose of 300 mg/kg (LD50 = 300 mg/kg), in an acute toxicity study. The possible antioxidant and neuroprotective activities of 14 were evaluated in irradiated mice. Compound 14 possessed in vivo AChE inhibitory activity and was able to modify the brain neurotransmitters. It was able to cause mitigation of gamma radiation-induced oxidative stress verified by the decline in Myeloperoxidase (MPO) and increase of glutathione (GSH) levels. Also, 14 restored the alterations in behavioral tests. Molecular docking of 14 was performed inside MPO and AChE active sites and showed the same binding interactions as that of the co-crystallized ligands considering the binding possibilities and energy scores. These findings would support that 14 could be considered a promising antioxidant with a neuromodulatory effect.

Novel Lawsone-Quinoxaline Hybrids as New Dual Binding Site Acetylcholinesterase Inhibitors

A new family of lawsone-quinoxaline hybrids was designed, synthesized, and evaluated as dual binding site cholinesterase inhibitors (ChEIs). In vitro tests revealed that compound 6d was the most potent AChEI (IC50 = 20 nM) and BChEI (IC50 = 220 nM). The compound 6d did not show cytotoxicity against the SH-SY5Y neuronal cells (GI50 > 100 μM). In silico and enzyme kinetic experiments demonstrated that compound 6d bound to both the catalytic anionic site and the peripheral anionic site of HuAChE. The lawsone-quinoxaline hybrids exhibited potential for further development of potent acetylcholinesterase inhibitors for the treatment of Alzheimer's disease.

Computational model for lipid binding regions in phospholipase (Ves a 1) from Vespa venom

The Thai banded tiger wasp (Vespa affinis) is a dangerous vespid species found in Southeast Asia, and its stings often result in fatalities due to the presence of lethal phospholipase A[Formula: see text], known as Vespapase or Ves a 1. Developing anti-venoms for Ves a 1 using chemical drugs, such as chemical drug guide, remains a challenging task. In this study, we screened 2056 drugs against the opening conformation of the venom using the ZINC 15 and e-Drug 3D databases. The binding free energy of the top five drug candidates complexed with Ves a 1 was calculated using 300-ns-MD trajectories. Our results revealed that voxilaprevir had a higher binding free energy at the catalytic sites than other drug candidates. Furthermore, the MD simulation results indicated that voxilaprevir formed stable conformations within the catalytic pocket. Consequently, voxilaprevir could act as a potent inhibitor, opening up avenues for the development of more effective anti-venom therapeutics for Ves a 1.

A Review on Recent Approaches on Molecular Docking Studies of Novel Compounds Targeting Acetylcholinesterase in Alzheimer Disease

Alzheimer's disease (AD), a neurodegenerative brain disorder that affects millions of people worldwide, is characterized by memory loss and cognitive decline. Low levels of acetylcholine and abnormal levels of beta-amyloid, T protein aggregation, inflammation, and oxidative stress, have been associated with AD, and therefore, research has been oriented towards the cholinergic system and primarily on acetylcholinesterase (AChE) inhibitors. In this review, we are focusing on the discovery of AChE inhibitors using computer-based modeling and simulation techniques, covering the recent literature from 2018-2022. More specifically, the review discusses the structures of novel, potent acetylcholinesterase inhibitors and their binding mode to AChE, as well as the physicochemical requirements for the design of potential AChE inhibitors.

Hydrazinyl thiazole linked indenoquinoxaline hybrids: Potential leads to treat hyperglycemia and oxidative stress; Multistep synthesis, α-amylase, α-glucosidase inhibitory and antioxidant activities

A library of hydrazinyl thiazole-linked indenoquinoxaline hybrids 1-36 were synthesized via a multistep reaction scheme. All synthesized compounds were characterized by various spectroscopic techniques including EI-MS (electron ionization mass spectrometry) and ¹H NMR (nuclear magnetic resonance spectroscopy). Compounds 1-36 were evaluated for their inhibitory potential against α-amylase, and α-glucosidase enzymes. Among thirty-six, compounds 2, 9, 10, 13, 15, 17, 21, 22, 31, and 36 showed excellent inhibition against α-amylase (IC₅₀ = 0.3-76.6 μM) and α-glucosidase (IC₅₀ = 1.1-92.2 μM). Results were compared to the standard acarbose (IC₅₀ = 13.5 ± 0.2 μM). All compounds were also evaluated for their DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity and compounds 2, 9, 10, 17, 21, 31, and 36 showed (SC₅₀ = 7.58-125.86 μM) as compared to the standard ascorbic acid (SC₅₀ = 21.50 ± 0.18 μM). Among this library, compounds 9 and 10 with a hydroxy group on the phenyl rings and thiosemicarbazide bearing intermediate 21 were identified as the most potent inhibitors against α-amylase, and α-glucosidase enzymes. The remaining compounds were found to be moderately active. The molecular docking studies were conducted to understand the binding mode of active inhibitors and kinetic studies of the active compounds followed competitive modes of inhibition.

Development of new donepezil analogs: synthesis, biological screening and in silico study rational

Fifteen new benzothiophene-based compounds were designed, synthesized, and evaluated as potential anti-Alzheimer agents. Most of the synthesized compounds exhibited remarkable AChE inhibitory activity and effectively inhibited self-mediated β-amyloid protein in vitro. Compound 3g (IC50 = 72.488 ± 3.69 μM) showed a significant β-amyloid inhibitory effect exceeding that of donepezil (IC50 = 87.414 ± 4.46 μM). Furthermore, compound 3j (IC50 = 0.498 ± 0.02 μM) showed the best inhibitory activity comparable to that of donepezil (IC50 = 0.404 ± 0.03 μM). The in vivo evaluation of the promising compounds (3g and 3j) confirmed a significant memory improvement in scopolamine-induced memory impairment model in mice. The molecular docking simulation of compounds 3g and 3j in Torpedo californica-AChE (TcAChE) active site showed a good agreement with the obtained screening results. The in silico ADMET and other physicochemical parameters were also reported.

Inhibitory potential of nitrogen, oxygen and sulfur containing heterocyclic scaffolds against acetylcholinesterase and butyrylcholinesterase

Heterocycles are the key structures in organic chemistry owing to their immense applications in the biological, chemical, and pharmaceutical fields. Heterocyclic compounds perform various noteworthy functions in nature, medication, innovation etc. Most frequently, pure nitrogen heterocycles or various positional combinations of nitrogen, oxygen, and sulfur atoms in five or six-membered rings can be found. Inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes is a popular strategy for the management of numerous mental diseases. In this context, cholinesterase inhibitors are utilized to relieve the symptoms of neurological illnesses like dementia and Alzheimer's disease (AD). The present review focuses on various heterocyclic scaffolds and their role in designing and developing new potential AChE and BChE inhibitors to treat AD. Moreover, a detailed structure-activity relationship (SAR) has been established for the future discovery of novel drugs for the treatment of AD. Most of the heterocyclic motifs have been used in the design of new potent cholinesterase inhibitors. In this regard, this review is an endeavor to summarize the biological and chemical studies over the past decade (2010-2022) describing the pursuit of new N, O and S containing heterocycles which can offer a rich supply of promising AChE and BChE inhibitory activities.

Evaluation of synthetic 2-aryl quinoxaline derivatives as α-amylase, α-glucosidase, acetylcholinesterase, and butyrylcholinesterase inhibitors

Variety of 2-aryl quinoxaline derivatives 1-23 were synthesized in good yields, by reacting 1,2-phenylenediamine with varyingly substituted phenacyl bromides in the presence of pyridine catalyst. All molecules 1-23 were characterized by spectroscopic techniques and evaluated for their diverse biological potential against α-amylase (α-AMY), α-glucosidase (α-GLU), acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) enzymes. Synthetic derivatives possess enhanced inhibitory potential against all enzymes at nanomolar concentrations. In particular, compound 14 was found much superior with IC₅₀ = 294.35, 198.21, 17.04, and 21.46 nM against α-AMY, α-GLU, AChE, and BChE, respectively, as compared to standard inhibitors. Furthermore, selected potent compounds, including 3, 4, 8, 14, 15, 17, and 18, were subjected to molecular docking studies to decipher the binding energies and interactions of ligands (synthetic molecules) with all four target enzymes.

In Vitro and In Silico Kinetic Studies of Patented 1,7-diEthyl and 1,7-diMethyl Aminoalkanol Derivatives as New Inhibitors of Acetylcholinesterase

Two aminoalkanol derivatives of 1,7-diEthyl-8,9-diphenyl-4azatricyclo (5.2.1.02.6) dec-8-ene-3,5,10-trione and two derivatives of 1,7-diMethyl-8,9-diphenyl-4-azatricyclo (5.2.1.02.6) dec-8-ene-3,5,10-trione were evaluated in vitro for their inhibition efficacy of acetylcholinesterase. The Km, Vmax, slope angles of Lineweaver-Burk plots, Ki and IC50 values showed that all four aminoalkanol derivatives are competitive inhibitors of acetylcholinesterase whose inhibitory potency depends, to a varying extent, on the nature of the four different substituents present in the main compound structure. Studies have shown that the most potent acetylcholinesterase inhibitors are derivatives containing isopropylamine and/or methyl substituents in their structure. In contrast, dimethylamine and/or ethyl substituents seem to have a weaker, albeit visible, effect on the inhibitory potency of acetylcholinesterase. Additionally, docking studies suggest that studied compounds binds with the peripheral anionic site and not enter into the catalytic pocket due to the presence of the sterically extended substituent.