Potent Butyrylcholinesterase Inhibitors Research Articles

Isolation, derivatization, in-vitro, and in-silico studies of potent butyrylcholinesterase inhibitors from Berberis parkeriana Schneid

Seven known isoquinoline alkaloids 1–7 were isolated from the root extracts of Berberis parkeriana Schneid. Nine new derivatives 8–16 of one of the isolated compounds, jatrorrhizine (7), were synthesized. All the isolated as well as derivatized compounds were evaluated for their in-vitro acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) inhibitory activity. Functionalized compounds selectively exhibited a potent-to-moderate activity with IC50 = 5.5 ± 0.3–124.5 ± 0.4 μM against butyrylcholinesterase enzyme. Among them, compound 15 was a potent BChE inhibitor (IC50 = 5.5 ± 0.3 μM), as compared to the standard drug galantamine hydrobromide (IC50 = 40.83 ± 0.37 μM). Active compounds were further subjected to kinetic, and molecular docking studies to predict their modes of inhibition, and interactions with the receptor (BChE), respectively. Enzyme kinetics studies showed that compounds 9 (IC50 = 25.3 ± 0.5 μM), and 14 (IC50 = 23.9 ± 0.5 μM) were non-competitive inhibitors, while compound 15 exhibited a competitive inhibition. In addition, these compounds were found to be non-cytotoxic against human fibroblast (BJ) cell line, except 9 (IC50 = 17.1 ± 1.0 μM), and 10 (IC50 = 18.4 ± 0.3 μM). Inhibition of cholinesterases is an important approach for development of drugs against Alzheimer’s disease, and thus discoveries presented here deserve further investigation.

Determination of biological studies and molecular docking calculations of isatin-thiosemicarbazone hybrid compounds

Design, synthesis, structural elucidation, and investigation of cytotoxic and antimicrobial activity, butyrylcholinesterase (BChE), and acetylcholinesterase (AChE) enzyme inhibition effects of isatin-thiosemicarbazone hybrid compounds (1–15) are reported in this study. Hybrid compounds (14 and 15) were synthesized, isolated, and characterized for the first time. FT-IR, 1H NMR, and 13C NMR spectroscopic methods and elemental analysis were used to characterize the structures of the compounds. In the enzymatic evaluation, hybrid compound 13 was observed as the most potent inhibitor of AChE with a Kİ value of 0.94 ± 0.13 µM (all compound Kİ values between 0.94 ± 0.13 and 4.47 ± 0.92), also this compound was observed as the most potent inhibitor of BChE with a Kİ value of 0.82 ± 0.11 µM (all compounds had Kİ values between of 0.82 ± 0.11 and 3.48 ± 0.92). Almost all compounds were shown better inhibition profile than standard compound. In the theoretical calculations, the comparison of the biological activities of isatin-thiosemicarbazone hybrid derivatives against enzymes was studied. The enzymes studied in docking calculations are AChE and BChE. Then, ADME/T analysis was conducted to examine the drug properties of these derivatives. Besides, the antimicrobial activity of these molecules was investigated by the microdilution method according to Clinical Laboratory Standards Institute (CLSI) criteria in the study. Cytotoxic activity of isatin-thiosemicarbazone hybrids was determined by the XTT cell viability assay on human breast cancer cell lines MCF-7 and MDA-MB-231. Among the hybrid compounds, compound 8 exhibited the most potent cytotoxic activity with IC50 values of 23.42 ± 0.21 µg/mL and 19.68 ± 0.23 µg/mL on MCF-7 and MDA-MB-231 cell lines, respectively. Overall, the hybridization of isatin and thiosemicarbazone skeleton has played an essential role in the inhibition of enzymes and cytotoxic activity.

Phytochemical Screening, In vitro Antioxidant and Enzyme Inhibitory Properties, and Acute Toxicity of Extracts from the Aerial Parts of Ephedra nebrodensis, a Source of Bioactive Compounds.

Due to the strong association between the chemistry of medicinal plants and their biological properties, it is important to determine their phytochemical composition to justify experimental tests. The aim of this study was to evaluate the in vitro antioxidant and the enzyme inhibitory properties and to identify the bioactive compounds present in the extracts of Ephedra nebrodensis growing in Algeria. Total phenolic and flavonoids content in these extracts were quantified by Folin- Ciocalteu and aluminum chloride methods. The antioxidant capacity was assessed using DPPH, ABTS, β-carotene/linoleic acid, CUPRAC and FRAP assays, and in vitro cholinesterase activity against acetylcholinesterase and butyrylcholinesterase were evaluated. The chemical constituents of the extracts were analyzed by high-performance liquid chromatography coupled with mass spectrometric detection and gas chromatography. For the acute toxicity study, extracts were administered to mice at single dose of 2 g/kg and 5 g/kg by gavage. Plant extracts were rich in phenolic compounds. Ethyl acetate extract presented the highest phenolic (238.44 ± 1.50 μg GAE /mg of extract) and flavonoid (21.12 ± 0.00 μg QE /mg of extract) contents. Likewise, ethyl acetate extract showed potent radical scavenging and reducing properties. Ethanol-acetone extract showed inhibitory activity against acetylcholinesterase, and was a potent inhibitor of butyrylcholinesterase. In all extracts, flavonoids were the most abundant compounds. The phytochemical investigation showed the presence of alkaloids (ephedrine and pseudo-ephedrine). In the acute toxicity, the LD50 was superior to 5 g/kg body weight. There were no alterations in the histology of the liver and kidneys. This study demonstrated a good antioxidant potential and anticholinesterase activity of aerial parts of E. nebrodensis.

Structural Insight of New Butyrylcholinesterase Inhibitors Based on Benzylbenzofuran Scaffold.

In the present work, we use a merger of computational and biochemical techniques as a rational guideline for structural modification of benzofuran derivatives to find pertinent structural features for the butyrylcholinesterase inhibitory activity and selectivity. Previously, we revealed a series of 2-phenylbenzofuran compounds that displayed a selective inhibitory activity for BChE. Here, in an effort to discover novel selective BChE inhibitors with favorable physicochemical and pharmacokinetic profiles, 2-benzylbenzofurans were designed, synthesized, and evaluated as BChE inhibitors. The 2-phenylbenzofuran scaffold structure is modified by introducing one methylene spacer between the benzofuran core and the 2-phenyl ring with a hydroxyl substituent in the para or meta position. Either position 5 or 7 of the benzofuran scaffold was substituted with a bromine or chlorine atom. Further assessment of the selected list of compounds indicated that the substituent’s nature and position determined their activity and selectivity. 5-bromo-2-(4-hydroxybenzyl)benzofuran 9B proved to be the most potent butyrylcholinesterase inhibitor (IC50 = 2.93 µM) of the studied series. Computational studies were carried out to correlate the theoretical and experimental binding affinity of the compounds to the BChE protein.

Design and synthesis of novel chalcone derivatives and evaluation of their inhibitory activities against acetylcholinesterase.

According to the cholinergic hypothesis, an increase in the acetylcholine level in Alzheimer's disease patients relatively slows down the symptoms of the disease. The most commonly used drug, donepezil, is a cholinesterase inhibitor. In this study, 12 new chalcones (2a-l) were designed and synthesized. In biological activity studies, the acetylcholinesterase (AChE) and butyrylcholinesterase inhibitory potentials of all compounds were evaluated using the in vitro Ellman method. The biological evaluation showed that compounds 2d, 2f, 2j, and 2l displayed significant activity against AChE. The compounds 2d, 2f, 2j, and 2l displayed IC50 values of 0.042, 0.024, 0.053, and 0.033 µM against AChE, respectively. The reference drug donepezil (IC50 = 0.021 µM) also displayed significant inhibition of AChE. The inhibitory activities of these compounds for β-amyloid plaque aggregation were investigated. The enzyme kinetic study was performed to observe the effect of the most active compound 2f on the substrate-enzyme relationship, and a mixed-type inhibition of AchE was determined. Further, docking simulation also revealed that these compounds (2d, 2f, 2j, and 2l) interacted with the enzyme active site in a similar manner to donepezil. The most active derivative, compound 2f, interacted with the amino acids Trp286, Phe295, Tyr341, Trp86, and Glu202.

Prospective Application of Two New Pyridine-Based Zinc (II) Amide Carboxylate in Management of Alzheimer's Disease: Synthesis, Characterization, Computational and in vitro Approaches.

BackgroundAlzheimer’s disease (AD) is a neurodegenerative illness described predominantly by dementia. Even though Alzheimer’s disease has been known for over a century, its origin remains a mystery, and researchers are exploring many therapy options, including the cholinesterase technique. A decreased acetylcholine ACh neurotransmitter level is believed to be among the important factors in the progression of Alzheimer’s disease.MethodsIn continuation of synthesizing potential anti-Alzheimer agents and known appreciative pharmacological potential of amide-containing compounds, this study presents the synthesis of two novel amide-based transition metal zinc (II) complexes, AAZ7 and AAZ8, attached with a heterocyclic pyridine ring, which was synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), elemental analysis, 1H_NMR, and 13C_NMR. FT-IR spectroscopic records showed the development of bidentate ligand as Δν value was decreased in both complexes when compared with the free ligand. Both of the synthesized complexes were analyzed for acetylcholinesterase and butyrylcholinesterase inhibitory potential along with the antioxidizing activity.ResultsImportantly, the complex of AAZ8 exhibited more potent activity giving IC50 values of 14 µg/mL and 18µg/mL as AChE and BChE cholinesterase inhibitors, respectively, when compared with standard positive control galantamine. Interestingly, AAZ8 also displayed promising antioxidant potential by showing IC50 values of 35 µg/mL for DPPH and 29 µg/mL for ABTS in comparison with positive control ascorbic acid.ConclusionHerein, we report two new amide carboxylate zinc (II) complexes which were potentially analyzed for various biological applications like acetylcholinesterase (AChE), butyrylcholinesterase (BChE) inhibitory potentials, and antioxidant assays. Computational docking studies also simulated results to understand the interactions. Additionally, thermodynamic parameters utilizing molecular dynamic simulation were performed to determine the ligand protein stability and flexibility that supported the results. Studies have shown that these compounds have the potential to be good anti-Alzheimer candidates for future studies due to inhibition of cholinesterase enzymes and display of free radical scavenging potential against DPPH as well as ABTS free radicals.

Incorporating Substrate Features in Fmoc Amino Acids to Develop Potent and Specific Butyrylcholinesterase Inhibitors for the Potential Treatment of Alzheimer's Disease

Alzheimer's Disease (AD) is a chronic neurodegenerative disease leading to irreversible memory loss and is the most common form of dementia. While a cure for AD is not available, inhibitors of the two major classes of cholinesterases, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), are under investigation to mitigate the effects of this disease. In individuals with AD, studies showed that BChE activity increased while AChE activity was similar. The increased BChE activity is suggested to deplete acetylcholine, a neurotransmitter, and contribute to dementia. We identified Fmoc-amino acids as BChE inhibitors, and a lysine-based compound that shares structural similarities with the substrate was one of the most potent inhibitors. Although the original inhibitor had the same positive charge as acetylcholine, the inhibitor lacked methyl groups found in the actual substrate. We hypothesized that methylation of the lysine side chain better mimics leading to better inhibitors. Due to challenges in synthesizing a trimethylated product, we first synthesized a dimethyl amino analog of lysine using 34% formaldehyde, acetic acid, NaBH4, and 1,4-dioxane. The product was purified by chromatography and characterized by NMR. Enzyme kinetics assays monitored by UV-Vis spectroscopy were then used to determine inhibition constants (KI values). The KI values for the dimethylated product Fmoc-Lys(CH3)2-O- was four-fold lower than Fmoc-Lys-O- (40 μM versus 150 μM, respectively), indicating the dimethylammonium compound is a better inhibitor. Studies comparing BChE and AChE inhibition indicated that the compound selectively targets BChE relative to AChE. Computational docking was then used to visualize possible binding sites of the inhibitor. The results suggested that the cationic amino group was binding in the BChE active site similar to the substrate and supports the hypothesis that adding substrate features lead to a more potent BChE inhibitor. Currently, we are testing different synthesis approaches to obtain the trimethyl ammonium compound to then further test the effect of introducing substrate features. Together, the results are aimed at systematically evaluating the contributions of introducing substrate features in enzyme inhibitors to develop more potent inhibitors.

Phenothiazine-Tacrine Heterodimers: Pursuing Multitarget Directed Approach in Alzheimer's Disease.

Since 2002, no clinical candidate against Alzheimer's disease has reached the market; hence, an effective therapy is urgently needed. We followed the so-called "multitarget directed ligand" approach and designed 36 novel tacrine-phenothiazine heterodimers which were in vitro evaluated for their anticholinesterase properties. The assessment of the structure-activity relationships of such derivatives highlighted compound 1dC as a potent and selective acetylcholinesterase inhibitor with IC50 = 8 nM and 1aA as a potent butyrylcholinesterase inhibitor with IC50 = 15 nM. Selected hybrids, namely, 1aC, 1bC, 1cC, 1dC, and 2dC, showed a significant inhibitory activity toward τ(306-336) peptide aggregation with percent inhibition ranging from 50.5 to 62.1%. Likewise, 1dC and 2dC exerted a remarkable ability to inhibit self-induced Aβ1-42 aggregation. Notwithstanding, in vitro studies displayed cytotoxicity toward HepG2 cells and cerebellar granule neurons; no pathophysiological abnormality was observed when 1dC was administered to mice at 14 mg/kg (i.p.). 1dC was also able to permeate to the CNS as shown by in vitro and in vivo models. The maximum brain concentration was close to the IC50 value for acetylcholinesterase inhibition with a relatively slow elimination half-time. 1dC showed an acceptable safety and good pharmacokinetic properties and a multifunctional biological profile.

Modulatory effect of pigeon pea-wheat biscuits on lipid profile, lipid peroxidation level, α-glucosidase, and butyrylcholinesterase activities in type-2 diabetic patients.

This study examined the modulatory effect of pigeon pea-wheat biscuits on lipid profile, lipid peroxidation level, α-glucosidase, and butyrylcholinesterase activities in type-2 diabetic patients. Composite flours were formulated using pigeon pea (PP) and wheat flour (WF) in ratio 100:0, 75:25, 50:50, 25:75, and 0:100. Sixty diabetic patients (DP) were treated with biscuit samples and the effect of the biscuits on the serum lipid profile, α-glucosidase, and butyrylcholinesterase (BChE) activities were evaluated. The result revealed that total cholesterol ranged from [100-PP (13.94±1.05mg/dl)-REF (40.46±3.09mg/dl)]; triglyceride [100-PP (28.00±1.14)-REF (115.00±7.05)], low-density lipoprotein (LDL-C) [100-PP (0.75±0.30)-REF (13.30±2.04)], high-density lipoprotein level(HDL-C) [REF (4.16±0.49)-100-PP (7.59±1.62)], LDL-C/HDL-C [100-PP (0.098±0.01)-REF (8.72±1.20)]. Alanine aminotransferase [CAB (3.10±0.51U/L)-REF (6.90±0.84U/L)]; aspartate aminotransferase [100-PP (9.50±0.61U/L)-REF (19.75±1.50U/L)]; alkaline phosphate (ALP) [CAB (26.99±2.13U/L)-BASELINE (UT) (92.40±5.41U/L]. α-glucosidase [100-PP (1.20±0.07)-REF (0.37±0.02)] and BChE [100-PP (1.12±0.09)-REF (1.30±0.01)] and Malondialdehyde [100-PP (0.33±0.08)-REF (0.37±0.04)]. 100-PP had an outstanding antihyperlipidemic potentials, not injurious to liver and might serve as good functional food that could help in preventing the risk of developing heart coronary disease, atherosclerosis, and stroke. PRACTICAL APPLICATIONS: This study provides vital information on the possible effect of pigeon pea-wheat biscuits on the serum lipid profile and peroxidation levels, α-glucosidase and butyrylcholinesterase of diabetic patients. The biscuits produced had lowering effect on cholesterol and low-density lipoprotein but improved high-density lipoprotein. All the biscuits have good lipid profile which may lower the risk of developing coronary heart diseases and vascular heart diseases in diabetes. However, 100-PP biscuit had an outstanding antihyperlipidemia action on the serum lipid levels of the patients. Also, it had the highest α-glucosidase, MDA, and BChE inhibitory potential. ALT, AST, and ALP serum activities of the patient's serum were greatly improved after treatment with the biscuits. 100-PP could lower the risk of developing heart coronary disease, atherosclerosis, and stroke.

Hydrazones of 4-(Trifluoromethyl)benzohydrazide as New Inhibitors of Acetyl- and Butyrylcholinesterase.

Based on the broad spectrum of biological activity of hydrazide–hydrazones, trifluoromethyl compounds, and clinical usage of cholinesterase inhibitors, we investigated hydrazones obtained from 4-(trifluoromethyl)benzohydrazide and various benzaldehydes or aliphatic ketones as potential inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). They were evaluated using Ellman’s spectrophotometric method. The hydrazide–hydrazones produced a dual inhibition of both cholinesterase enzymes with IC50 values of 46.8–137.7 µM and 19.1–881.1 µM for AChE and BuChE, respectively. The majority of the compounds were stronger inhibitors of AChE; four of them (2-bromobenzaldehyde, 3-(trifluoromethyl)benzaldehyde, cyclohexanone, and camphor-based 2o, 2p, 3c, and 3d, respectively) produced a balanced inhibition of the enzymes and only 2-chloro/trifluoromethyl benzylidene derivatives 2d and 2q were found to be more potent inhibitors of BuChE. 4-(Trifluoromethyl)-N’-[4-(trifluoromethyl)benzylidene]benzohydrazide 2l produced the strongest inhibition of AChE via mixed-type inhibition determined experimentally. Structure–activity relationships were identified. The compounds fit physicochemical space for targeting central nervous systems with no apparent cytotoxicity for eukaryotic cell line together. The study provides new insights into this CF3-hydrazide–hydrazone scaffold.

Novel arylcarbamate-N-acylhydrazones derivatives as promising BuChE inhibitors: Design, synthesis, molecular modeling and biological evaluation

A novel series of arylcarbamate-N-acylhydrazones derivatives have been designed and synthesized as potential anti-cholinesterase agents. In vitro studies revealed that these compounds demonstrated selective for butyrylcholinesterase (BuChE) with potent inhibitory activity. The compounds 10a-d, 12b and 12d were the most potent BuChE inhibitors with IC50 values of 0.07–2.07 µM, highlighting the compound 10c (IC50 = 0.07 µM) which showed inhibitory activity 50 times greater than the reference drug donepezil (IC50 = 3.54 µM). The activity data indicates that the position of the carbamate group in the aromatic ring has a greater influence on the inhibitory activity of the derivatives. The enzyme kinetics studies indicate that the compound 10c has a non-competitive inhibition against BuChE with Ki value of 0.097 mM. Molecular modeling studies corroborated the in vitro inhibitory mode of interaction and show that compound 10c is stabilized into hBuChE by strong hydrogen bond interaction with Tyr128, π-π stacking interaction with Trp82 and CH⋯O interactions with His438, Gly121 and Glu197. Based on these data, compound10cwas identified as low-cost promising candidate for a drug prototype for AD treatment.

Benzobicyclo[3.2.1]octene Derivatives as a New Class of Cholinesterase Inhibitors.

A library of amine, oxime, ether, epoxy and acyl derivatives of the benzobicyclo[3.2.1]octene were synthesized and evaluated as inhibitors of both human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The majority of the tested compounds exhibited higher selectivity for BChE. Structural adjustment for AChE seems to have been achieved by acylation, and the furan ring opening of furo-benzobicyclo[3.2.1]octadiene results for compound 51 with the highest AChE affinity (IC50 = 8.3 µM). Interestingly, its analogue, an oxime ether with a benzobicyclo[3.2.1]-skeleton, compound 32 was one of the most potent BChE inhibitors in this study (IC50 = 31 µM), but not as potent as endo-43, an ether derivative of the benzobicyclo[3.2.1]octene with an additional phenyl substituent (IC50 = 17 µM). Therefore, we identified several cholinesterase inhibitors with a potential for further development as potential drugs for the treatment of neurodegenerative diseases.

Synthesis of Benzimidazole-Based Analogs as Anti Alzheimer's Disease Compounds and Their Molecular Docking Studies.

We synthesized 10 analogs of benzimidazole-based thiosemicarbazide 1 (a–j) and 13 benzimidazole-based Schiff bases 2 (a–m), and characterized by various spectroscopic techniques and evaluated in vitro for acetylcholinesterase (AchE) and butyrylcholinesterase (BchE) inhibition activities. All the synthesized analogs showed varying degrees of acetylcholinesterase and butyrylcholinesterase inhibitory potentials in comparison to the standard drug (IC50 = 0.016 and 4.5 µM. Amongst these analogs 1 (a–j), compounds 1b, 1c, and 1g having IC50 values 1.30, 0.60, and 2.40 µM, respectively, showed good acetylcholinesterase inhibition when compared with the standard. These compounds also showed moderate butyrylcholinesterase inhibition having IC50 values of 2.40, 1.50, and 2.40 µM, respectively. The rest of the compounds of this series also showed moderate to weak inhibition. While amongst the second series of analogs 2 (a–m), compounds 2c, 2e, and 2h having IC50 values of 1.50, 0.60, and 0.90 µM, respectively, showed moderate acetylcholinesterase inhibition when compared to donepezil. Structure Aactivity Relation of both synthesized series has been carried out. The binding interactions between the synthesized analogs and the enzymes were identified through molecular docking simulations.

Dual‐Target‐Directed Ligand Displaying Selective Butyrylcholinesterase Inhibitory and Neurite Promoting Activities as a Potential Therapeutic for Alzheimer's Disease

AbstractNovel small molecules were synthesized in the quest to search for multi‐target directed ligand for Alzheimer's disease. From the preliminary synthesis, ethyl 4‐((cyclohexylmethyl)amino)‐3‐nitrobenzoate (2 h) showed good butyrylcholinesterase (BChE) inhibitory activity. Modifications carried out on compound 2 h by removing the nitro group resulted in the identification of ethyl 4‐((cyclohexylmethyl)amino)benzoate (3 h) as a selective and potent BChE inhibitor (IC50=0.735 μM; BChE selectivity>100‐fold over acetylcholinesterase (AChE)). Furthermore, compound 3 h was shown to be able to promote neurite outgrowth in SH‐SY5Y cells. No significant cytotoxicity was exhibited by compound 3 h, up till the highest concentration tested (25 μM). The compound was also predicted to have good permeability across the lipid infused bilayer, indicating its potential to cross the blood‐brain barrier. These results warrant further investigations on compound 3 h as a potential treatment for Alzheimer's disease.

Highly potent cholinesterase inhibition of geranylated xanthones from Garcinia fusca and molecular docking studies

Three new oxygenated xanthones, fuscaxanthones L-N (1–3), and 14 known xanthones 4–17, together with the other known metabolites 18–20 were isolated from the stem barks of Garcinia fusca Pierre. Their chemical structures were determined based on NMR and MS spectroscopic data analysis, as well as single X-ray crystallography. The geranylated compounds, cowanin (13), cowagarcinone E (15), norcowanin (16) and cowanol (17) exhibited potent inhibitions against acetylcholinesterase (AChE) (IC50 0.33–1.09 μM) and butyrylcholinesterase (BChE) (IC50 0.048–1.84 μM), which were more active than the reference drug, galanthamine. Compound 15 was highly potent BChE inhibitor (IC50 0.048 μM) and was 76-fold more potent than the drug. Structure-activity relationship studies indicated that the C-2 prenyl and C-8 geranyl substituents in the tetraoxygenated scaffold are important for high activity. Molecular docking studies revealed that the leads 13 and 15–17 showed similar binding orientations on both enzymes and very well-fitted at the double binding active sites of PAS and CAS with strong hydrophobic interactions from both isoprenyl side chains.

SAR based in-vitro anticholinesterase and molecular docking studies of nitrogenous progesterone derivatives

Progesterone is a steroidal hormone that has been described with pathogenic features of brain dysfunction, realized with advanced age-related neurodegenerative diseases such as Alzheimer’s disease. In this study, sixteen nitrogenous derivatives of progesterone which we previously synthesized have been used for Alzheimer targets. The progesterone derivatives (1–16) were screened for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory potentials in a dose-dependent manner. All the compounds exhibited overwhelming AChE inhibitions, with IC50 values ranging from 14.40 to 40.37 μM. Similarly, the BChE inhibitory potentials of our compounds were also dominant with IC50values between 20.08 and 46.84 μM. In comparison to our compounds, the standard drug galantamine attain IC50 values of 12.03 and 18.20 μM against AChE and BChE respectively. Molecular docking studies suggested that the compounds exerted their inhibitory activity by binding to the active site of the enzyme. The cholinergic system plays an important role in the regulation of learning and memory processes and has been a major target for the design of anti-Alzheimer’s drugs. Therefore, these nitrogen-containing progesterone derivatives will be of potential interest to researchers working in AD for developing new drugs or chemical tools to study the disease.

Chiral Separation, X-ray Structure, and Biological Evaluation of a Potent and Reversible Dual Binding Site AChE Inhibitor

Acetylcholinesterase (AChE) inhibitors (AChEIs) still remain the leading therapeutic options for the symptomatic treatment of cognitive deficits associated with mild-to-moderate Alzheimer's disease. The search for new AChEIs benefits from well-established knowledge of the molecular interactions of selective AChEIs, such as donepezil and related dual binding site inhibitors. Starting from a previously disclosed coumarin-based inhibitor (±)-cis-1, active as racemate in the nanomolar range toward AChE, we proceeded on a double track by (i) achieving chiral resolution of the enantiomers of 1 by HPLC and (ii) preparing two close achiral analogues of 1, i.e., compounds 4 and 6. An eudismic ratio as high as 20 was observed for the (-) enantiomer of cis-1. The X-ray crystal structure of the complex between the (-)-cis-1 eutomer (coded as MC1420) and T. californica AChE was determined at 2.8 Å, and docking calculation results suggested that the eutomer in (1R,3S) absolute configuration should be energetically more favored in binding the enzyme than the eutomer in (1S,3R) configuration. The achiral analogues 4 and 6 were less effective in inhibiting AChE compared to (±)-cis-1, but interestingly butylamide 4 emerged as a potent inhibitor of butyrylcholinesterase (BChE).

Discovery of potent and selective butyrylcholinesterase inhibitors through the use of pharmacophore-based screening

Cholinesterase inhibitors have long been used in the treatment of Alzheimer’s Disease (AD) via the protection of acetylcholine levels. However, recent research has shown that the specific inhibition of butyrylcholinesterase (BChE) could better ameliorate symptoms within patients. In addition, it has recently been shown that selective inhibition of BChE can also significantly attenuate the toxicity and physiological effects of heroin. Currently, there are no specific and potent inhibitors of BChE approved for use in AD or heroin abuse. Through a combined use of in silico and in vitro screening, we have found three compounds with sub-50 nM IC50 values that specifically target BChE. These newly discovered BChE inhibitors can act as the lead scaffolds for future development of the desirably potent and selective BChE inhibitors.

Synthesis, molecular docking studies, and biological evaluation of novel alkyl bis(4-amino-5-cyanopyrimidine) derivatives.

A series of bis(4-amino-5-cyano-pyrimidines) was synthesized and evaluated as dual inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). To further explore the multifunctional properties of the new derivatives, their antioxidant and antibacterial activities were also tested. The results showed that most of these compounds could effectively inhibit AChE and BChE. Particularly, compound 7c exhibited the best AChE inhibitory activity (IC50 = 5.72 ± 1.53 μM), whereas compound 7h was identified as the most potent BChE inhibitor (IC50 = 12.19 ± 0.57 μM). Molecular modeling study revealed that compounds 7c, 7f, and 7b showed a higher inhibitory activity than that of galantamine against both AChE and BChE. Anticholinesterase activity of compounds 7h, 7b, and 7c was significant in vitro and in silico for both enzymes, since these compounds have hydrophobic rings (Br-phenyl, dimethyl, and methoxyphenyl), which bind very well in both sites. In addition to cholinesterase inhibitory activities, these compounds showed different levels of antioxidant activities. Indeed, in the superoxide-dimethyl sulfoxide alkaline assay, compound 7j showed very high inhibition (IC50 = 0.37 ± 0.28 μM). Also, compound 7l exhibited strong and good antibacterial activity against Staphylococcus epidermidis and Staphylococcus aureus, respectively. Taking into account the results of biological evaluation, further modifications will be designed to increase potency on different targets. In this study, the obtained results can be a new starting point for further development of multifunctional agents for the treatment of Alzheimer's disease.

Structural aspects of 4-aminoquinolines as reversible inhibitors of human acetylcholinesterase and butyrylcholinesterase

Eight derivatives of 4-aminoquinolines differing in the substituents attached to the C(4)-amino group and C(7) were synthesised and tested as inhibitors of human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Both enzymes were inhibited by all of the compounds with inhibition constants (Ki) ranging from 0.50 to 50 μM exhibiting slight selectivity toward AChE over BChE. The most potent inhibitors of AChE were compounds with an n-octylamino chain or adamantyl group. The shortening of the chain length resulted in a decrease in AChE inhibition by 5–20 times. Docking studies revealed that the quinoline group within the AChE active site was positioned in the choline binding site, while the C(4)-amino group substituents, depending on their lipophilicity, could establish hydrogen bonds or π-interactions with residues of the peripheral anionic site. The most potent inhibitors of BChE were compounds with the most voluminous substituent on C(4)-amino group (adamantyl) or those with a stronger electron withdrawing substituent on C(7) (trifluormethyl group). Based on AChE inhibition, compounds with an n-octylamino chain or adamantyl substituent were shown to possess the capacity for further development as potential drugs for treatment of neurodegenerative diseases.