Design, synthesis and anticholinergic properties of novel α-benzyl dopamine, tyramine, and phenethylamine derivatives.

Due to the important biological properties of dopamine, phenethylamine, and tyramine derivatives in the central nervous system, herein the synthesis of novel α-benzyl dopamine, phenethylamine, and tyramine derivatives is described. The title compounds were synthesized starting from 3-phenylpropanoic acids and methoxybenzenes in six or seven steps. Firstly, 3-(2,3-dimethoxyphenyl)propanoic acid (11) and 3-(3,4-dimethoxyphenyl)propanoic acid (12) were selectively brominated with N-bromosuccinimide (NBS). The Friedel-Crafts acylation of methoxylated benzenes with these brominated acids or commercially available 3-phenylpropanoic acid in polyphosphoric acid gave the desired dihydrochalcones. α-Carboxylation of dihydrochalcones, reduction of benzylic carbonyl groups, hydrolysis of esters to acid derivatives, and the Curtius rearrangement reaction of acids followed by in situ synthesis of carbamates from alkyl isocyanates and hydrogenolysis of the carbamates afforded the title compounds in good total yields. Alzheimer's disease (AD) and Parkinson's disease (PD) are chronic neurodegenerative diseases that become serious over time. However, the exact pathophysiology of both diseases has not been revealed yet. There have been many different approaches to the treatment of patients for many years, especially studies on the cholinergic system cover a wide area. Within the scope of this study, the inhibition effects of dopamine-derived carbamates and amine salts on the cholinergic enzymes AChE and BChE were examined. Dopamine-derived carbamate 24a-i showed inhibition in the micro-nanomolar range; compound 24d showed a Ki value of 26.79 nM against AChE and 3.33 nM against BChE, while another molecule, 24i, showed a Ki range of 27.24 nM and 0.92 nM against AChE and BChE, respectively. AChE and BChE were effectively inhibited by dopamine-derived amine salts 25j-s, with Ki values in the range of 17.70 to 468.57 µM and 0.76-211.23 µM, respectively. Additionally, 24c, 24e and 25m were determined to be 60, 276 and 90 times more selective against BChE than AChE, respectively.

Piperazine-2-carboxylic acid derivatives as MTDLs anti-Alzheimer agents: Anticholinesterase activity, mechanistic aspect, and molecular modeling studies.

Development of Multitarget-Directed Ligands (MTDLs) is a promising approach to combat the complex etiologies of Alzheimer's disease (AD). Herein we report the design, synthesis, and characterization of a new series of 1,4-bisbenzylpiperazine-2-carboxylic acid derivatives 3-5(a-g), 7a-f, 8a-s, and their piperazine-2-yl-1,3,4-oxadiazole analogs 6a-g. In vitro inhibitory effect against Electrophorus electricus acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) from Equine serum was evaluated using modified Ellman's method, considering donepezil and tacrine as reference drugs. Lineweaver-Burk plot analysis of the results proved competitive inhibition of AChE and BChE with Ki values, in low micromolar range. The free carboxylic acid series 4a-g showed enhanced selectivity for AChE. Hence, 4c, 1,4-bis (4-chlorobenzyl)-piperazinyl-2-carboxylic acid), was the most active member of this series (Ki (AChE) = 10.18 ± 1.00 µM) with clear selectivity for AChE (SI âˆ¼ 17.90). However, the hydroxamic acids 7a-f and carboxamides 8a-s congeners were more potent and selective inhibitors of BChE (SI âˆ¼ 5.38 - 21862.5). Extraordinarily, 1,4-bis (2-chlorobenzyl)-piperazinyl-2-hydroxamic acid 7b showed promising inhibitory activity against BChE enzyme (Ki = 1.6 ± 0.08 nM, SI = 21862.5), that was significantly superior to that elicited by donepezil (Ki = 12.5 ± 2.6 µM) and tacrine (Ki = 17.3 ± 2.3 nM). Cytotoxicity assessment of 4c and 7b, on human neuroblastoma (SH-SY5Y) cell lines, revealed lower toxicity than staurosporine and was nearly comparable to that of donepezil. Molecular docking and molecular dynamics simulation afforded unblemished insights into the structure-activity relationships for AChE and BChE inhibition. The results showed stable binding with fair H-bonding, hydrophobic and/or ionic interactions to the catalytic and peripheral anionic sites of the enzymes. In silico predicted ADME and physicochemical properties of conjugates showed good CNS bioavailability and safety parameters. In this regard, compound (7b) might be considered as a promising inhibitor of BChE with an innovative donepezil-based anti-Alzheimer activity. Further assessments of the most potent AChE and BChE inhibitors as potential MTDLs anti-Alzheimer's agents are under investigation with our research group and will be published later.

Assessment of Anticholinergic and Antidiabetic Properties of Some Natural and Synthetic Molecules: an In Vitro and In Silico Approach.

INTRODUCTION: In this study, it was aimed to determine the in vitro and in silico effects of some natural and synthetic molecules on acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and α-glucosidase enzymes. BACKGROUND: Alzheimer's disease (AD) and Type II diabetes mellitus (T2DM), which are considered amongst the most important diseases of today's world. However, the side effects of therapeutic agents used in both diseases limit their use. Therefore, it is important to develop drugs with high therapeutic efficacy and better pharmacological profile. OBJECTIVE: This study sets out to determine the related enzyme inhibitors used in the treatment of AD and T2DM, which are considered amongst the most important diseases of today's world. METHODS: In the current study, the in vitro and in silico effects of dienestrol, hesperetin, L-thyroxine, 3,3',5-Triiodo-L-thyronine (T3) and dobutamine molecules on AChE, BChE and α-glycosidase enzyme activities were investigated. RESULTS: All the molecules showed an inhibitory effect on the enzymes. The IC50 and Ki values of the L-Thyroxine molecule, which showed the strongest inhibition effect for the AChE enzyme, were determined as 1.71 µM and 0.83±0.195 µM, respectively. In addition, dienestrol, T3 and dobutamine molecules showed a more substantial inhibition effect than tacrine. Dobutamine molecule showed the most substantial inhibition effect for BChE enzyme, and IC50 and Ki values were determined as 1.83 µM and 0.845±0.143 µM, respectively. The IC50 and Ki values for the hesperetin molecule, which showed the strongest inhibition for the α-glycosidase enzyme, were determined as 13.57 µM and 12.33±2.57 µM, respectively. CONCLUSION: According to the results obtained, it may be said that the molecules used in the study are potential inhibitor candidates for AChE, BChE and α-glycosidase.

Cholinesterases, carbonic anhydrase inhibitory properties and in silico studies of novel substituted benzylamines derived from dihydrochalcones.

A series of novel urea, sulfamide and N,N-dipropargyl substituted benzylamines were synthesized from dihydrochalcones. The synthesized compounds were evaluated for their cholinesterases and carbonic anhydrase inhibitory actions. The known dihydrochalcones were converted into four new benzylamines via reductive amination. N,N-Dipropargylamines, ureas and sulfamides were synthesized following the reactions of benzylamines with propargyl bromide, N,N-dimethyl sulfamoyl chloride and N,N-dimethyl carbamoyl chloride. The novel substituted benzylamines derived from dihydrochalcones were evaluated against some enzymes such as human erythrocyte carbonic anhydrase I and II isoenzymes (hCA I and hCA II), acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The novel substituted benzylamines derived from dihydrochalcones exhibited Ki values in the range of 0.121-1.007 nM on hCA I, and 0.077-0.487 nM on hCA II closely related to several pathological processes. On the other hand, Ki values were found in the range of 0.112-0.558 nM on AChE, 0.061-0.388 nM on BChE. As a result, novel substituted benzylamines derived from dihydrochalcones showed potent inhibitory profiles against indicated metabolic enzymes. In addition, Induced-Fit Docking (IFD) simulations and ADME prediction studies have also been carried out to elucidate the inhibition mechanisms and drug-likeness of the synthesized compounds. Therefore, these results can make significant contributions to the treatment of some global diseases, especially Alzheimer's diseases and glaucoma, and the development of new drugs.

Synthesis of novel sulfonamides with anti-Alzheimer and antioxidant capacities.

A series of novel dopamine analogs incorporating urea and sulfonamide functional groups was synthesized from 3,4-dimethoxyphenethylamine. The reaction of 3,4-dimethoxyphenethylamine with N,N-dimethylcarbamoyl chloride, followed by the sulfonyl chlorination of the urea derivative, gave benzene-1-sulfonyl chloride 9, which was reacted with NH3 (aq) or N-alkyl amines to give related sulfonamides. The O-demethylation reaction of the subsequent compounds with BBr3 afforded four novel phenolic dopamine analogs including sulfonamide and urea in the same structure. The anticholinergic and antioxidant effects of the synthesized compounds were examined. Compound 13 exhibited inhibition at the micromolar level for both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The IC50 value of 13 was calculated as 298 ± 43 µM for AChE and 321 ± 29 µM for BChE. The antioxidant and antiradical effects of the molecules were investigated by five different methods. Among the synthesized compounds 10-18, the best antioxidant and antiradical activities belong to the phenolic compounds 15-18. Compounds 16 and 18 have a higher reducing power than the standards used, that is, butylated hydroxytoluene, butylated hydroxyanisole, Trolox, and α-tocopherol, for Fe3+ -Fe2+ and Cu2+ -Cu+ reducing activities. For the DPPH• radical scavenging method, compounds 16-18 have a much better scavenging power than the standard molecules. In addition, it has been determined by the induced-fit docking method that compound 13 is well-fitted in the active site of the enzymes. ADME studies reveal that the pharmacokinetic and physicochemical properties of all synthesized compounds are within an acceptable range.

Concise syntheses and some biological activities of dl-2,5-di-O-methyl-chiro-inositol, dl-1,4-di-O-methyl-scyllo-inositol, and dl-1,6-dibromo-1,6-dideoxy-2,5-di-O-methyl-chiro-inositol.

The regio- and stereospecific synthesis of O-methyl-chiro-inositols and O-methyl-scyllo-inositol was achieved, starting from p-benzoquinone. After preparing dimethoxy conduritol-B as a key compound, regiospecific bromination of the alkene moiety of dimethoxy conduritol-B and acid-catalyzed ring opening of dimethoxydiacetate conduritol-B epoxide with Ac2 O afforded the desired new chiro-inositol derivatives and scyllo-inositol derivative, respectively. Spectroscopic methods were employed for the characterization of all synthesized compounds. The novel inositols (11-17) had effective inhibition profiles against human carbonic anhydrase isoenzymes I and II (hCA I and II) and acetylcholinesterase (AChE). The novel inositols 11-17 were found to be effective inhibitors against AChE, hCA I, and hCA II enzymes. Ki values were calculated in the range of 87.59 ± 7.011 to 237.95 ± 17.75 µM for hCA I, 65.08 ± 12.39 to 538.98 ± 61.26 µM for hCA II, and 193.28 ± 43.13 to 765.08 ± 209.77 µM for AChE, respectively. Also, due to the inhibitory effects of the novel inositols 11-17 against the tested enzymes, these novel inositols are potential drug candidates to treat some diseases such as glaucoma, epilepsy, leukemia, and Alzheimer's disease.

human monoamine oxidase (hMAO) A and hMAO B inhibitors from Artemisia dracunculus L. herniarin and skimmin: human mononamine oxidase A and B inhibitors from A. dracunculus L.

The aim of this study was to investigate the effects of extracts and pure Artemisia dracunculus L. (tarragon) metabolites on the antimonoamine oxidase and anticholinesterase activities. The compounds were characterized as stigmasterol (1), herniarin (2), (2E,4E)-1-(piperidin-1-yl)undeca-2,4-diene-8,10-diyn-1-one (3), (2E,4E)-N-isobutylundeca-2,4-dien-8,10-diynamide (4), 3,4-dehydroherniarin (5) and skimmin (6) by 1H-NMR, 13C-NMR, 1D and 2D NMR methods. The compounds 5 and 6 were isolated from tarragon for the first time. The extracts and pure compounds have inhibitory effects on the human monoamine oxidase (hMAO) A and B enzymes, whereas they did not exhibit any anticholinesterase activities. Among the tarragon compounds, only 2 and 6 compounds showed the inhibitory effects against hMAO A (IC50 = 51.76 and 73.47 µM, respectively) and hMAO B (IC50 = 0.84 and 1.63 mM, respectively). In the study, herniarin content in the extracts was also analysed by high-performance liquid chromatography and it was found that there was a relationship between the inhibition effects of the extracts and their herniarin content.

Potent Acetylcholinesterase Inhibitors: Potential Drugs for Alzheimer's Disease.

Alzheimer's disease (AD) is one of the cognitive or memory-related impairments occurring with advancing age. Since its exact mechanism is not known, the full therapy has still not been found. Acetylcholinesterase (AChE) has been reported to be a viable therapeutic target for the treatment of AD and other dementias. To this end, acetylcholinesterase inhibitors (AChEIs) are commonly used. AChE is a member of the hydrolase enzyme family. A hydrolase is an enzyme that catalyzes the hydrolysis of a chemical bond. AChE is useful for the development of novel and mechanism-based inhibitors. It has a role in the breakdown of acetylcholine (ACh) neurotransmitters, such as acetylcholinemediated neurotransmission. AChEIs are the most effective approaches to treat AD. AChE hydrolyzes ACh to acetate and choline, as an important neurotransmitter substance. Recently, Gülçin and his group explored new AChEIs. The most suggested mechanism for AD is the deficiency of ACh, which is an important neurotransmitter. In this regard, AChEIs are commonly used for the symptomatic treatment of AD. They act in different ways, such as by inhibiting AChE, protecting cells from free radical toxicity and ß-amyloid-induced injury or inhibiting the release of cytokines from microglia and monocytes. This review focuses on the role of AChEIs in AD using commonly available drugs. Also, the aim of this review is to research and discuss the role of AChEIs in AD using commonly available drugs. Therefore, in our review, related topics like AD and AChEIs are highlighted. Also, the latest work related to AChEIs is compiled. In recent research studies, novel natural and synthetic AChEIs, used for AD, are quite noteworthy. These studies can be very promising in detecting potent drugs against AD.

Design, synthesis, in vitro and in vivo evaluation of novel pyrrolizine-based compounds with potential activity as cholinesterase inhibitors and anti-Alzheimer's agents.

Novel series of pyrrolizine based compounds (4-6 and 9-11) were designed, synthesized and evaluated as potential anti-Alzheimer agents. Most of the tested compounds showed selectivity to hAChE over hBChE and effectively inhibited self-induced amyloid beta aggregation in vitro. Among these derivatives, compound 10 displayed high selectivity towards hAChE (Ki = 1.47 ±â€¯0.63 µM for hAChE and Ki = 40.15 ±â€¯3.31 µM for hBChE). However, compound 11 displayed dual inhibitory effect against hAChE and hBChE at submicromolar range (Ki = 0.40 ±â€¯0.03 and 0.129 ±â€¯0.009 µM, respectively). Kinetic studies of the new ligands showed competitive type inhibition for both hAChE and hBChE. Moreover, compounds 10 and 11 showed lower or comparable cytotoxicity to donepezil against human neuroblastoma (SH-SY5Y) and normal human hepatic (THLE2) cell lines. In vivo studies confirmed that both compounds were able to improve cognitive dysfunction of scopolamine-induced AD mice. Finally, molecular docking simulation of compounds 10 and 11 in hAChE active site showed good agreement with the obtained pharmaco-biological results.

Synthesis of novel sulfamides incorporating phenethylamines and determination of their inhibition profiles against some metabolic enzymes.

A series of sulfamides were synthesized and evaluated for their acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and carbonic anhydrase inhibition properties. The synthesis of sulfamides was achieved by the reactions of phenethylamines with N,N-dimethylsulfamoyl chloride in the presence of Et3 N. The methoxylated sulfamides were converted into their phenolic derivatives with BBr3 for structure-activity relationships. The synthesized sulfamide/phenolic sulfamide derivatives were investigated as cholinesterase inhibitors and their relative role in AChE versus BChE inhibition was defined. Sulfamide/phenolic sulfamide derivatives are known as important carbonic anhydrase inhibitors; therefore, the synthesized compounds were investigated for inhibitory effects on both carbonic anhydrase isoenzymes. Additionally, we evaluated four different enzymes, which were inhibited in the low nanomolar range by these compounds. According to the present studies, for AChE, BChE, and carbonic anhydrase I and II, the ranges of results are recorded as 0.027-0.076 nM, 0.075-0.327 nM, 0.123-0.678 nM, and 0.024-0.688 nM, respectively.

The synthesis of novel sulfamides derived from ß-benzylphenethylamines as acetylcholinesterase, butyrylcholinesterase and carbonic anhydrase enzymes inhibitors.

In this study, a series of novel ß-benzylphenethylamines and their sulfamide derivatives were synthesized starting from (Z)-2,3-diphenylacrylonitriles. Pd-C catalysed hydrogenation of diphenylacrylonitriles, reduction of propanenitriles with LiAlH4 in the presence of AlCl3 followed by addition of conc. HCl afforded ß-benzylphenethylamine hydrochloride salts. The reactions of these amine hydrochloride salts with chlorosulfonyl isocyanate (CSI) in the presence of tert-BuOH and excess Et3N gave sulfamoylcarbamates. Removing of Boc group from the synthesized sulfamoylcarbamates with trifluoroacetic acid (TFA) yielded novel sulfamides in good yields. These novel sulfamides derived from ß-benzylphenethylamines were effective inhibitors of the cytosolic carbonic anhydrase I and II isoenzymes (hCA I and II), acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with Ki values in the range of 0.278-2.260nM for hCA I, 0.187-1.478nM for hCA II, 0.127-2.452nM for AChE and 0.494-1.790nM for BChE. The inhibitory effects of the synthesized novel sulfamides derived from ß-benzylphenethylamines were compared to those of acetazolamide and dorzolamide as clinical hCA I and II isoenzymes inhibitors and tacrine as a clinical AChE and BChE enzymes inhibitors. In addition to in vitro tests, molecular modeling approaches are implemented not only for prediction of the binding affinities of the compounds but also to study their inhibition mechanisms in atomic level at the catalytic domains.

Synephrine and phenylephrine act as α-amylase, α-glycosidase, acetylcholinesterase, butyrylcholinesterase, and carbonic anhydrase enzymes inhibitors.

In this paper, synephrine and phenylephrine compounds showed excellent inhibitory effects against human carbonic anhydrase (hCA) isoforms I and II, α-amylase, α-glycosidase, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE). Synephrine and phenylephrine had Ki values of 199.02 ± 16.01 and 65.01 ± 5.00 µM against hCA I and 336.02 ± 74.01 and 92.04  ±  18.03 µM against hCA II, respectively. On the other hand, their Ki values were found to be 169.10  ±  80.03 and 88.03  ±  5.01 nM against AChE and 177.06  ±  6.01 and 78.03  ±  3.05 nM against BChE, respectively. α-Amylase and α-glycosidase enzymes were easily inhibited by these compounds. α-Glycosidase inhibitors, generally defined to as starch blockers, are anti-diabetic drugs that help to decrease post comestible blood glucose levels.

The effect of caffeic acid phenethyl ester (CAPE) on metabolic enzymes including acetylcholinesterase, butyrylcholinesterase, glutathione S-transferase, lactoperoxidase, and carbonic anhydrase isoenzymes I, II, IX, and XII.

Caffeic acid phenethyl ester (CAPE) is an active component of honeybee propolis extracts. Carbonic anhydrases (CAs, EC 4.2.1.1) are widespread and intensively studied metalloenzymes present in higher vertebrates including humans as many diverse isoforms. Acetylcholinesterase (AChE) is responsible for acetyl choline (ACh) hydrolysis and plays a fundamental role in nerve impulse transmission by terminating the action of the ACh neurotransmitter at cholinergic synapses and neuromuscular junctions. Butyrylcholinesterase (BChE) is another enzyme abundantly present in the liver and released into blood in a soluble form. Lactoperoxidase (LPO) is an enzyme involved in fighting pathogenic microorganisms whereas glutathione S-transferases (GSTs) are dimeric proteins present both in prokaryotic and eukaryotic organisms and involved in cellular detoxification mechanisms. In the present study, the inhibition effect of CAPE on human carbonic anhydrase (hCA) isoforms I, II, IX, and XII, AChE, BChE, LPO, and GST was evaluated. CAPE inhibited these enzymes with Kis in the range between micromolar to picomolar. The best inhibitory effect was observed against AChE and BChE.

Discovery of potent carbonic anhydrase and acetylcholine esterase inhibitors: novel sulfamoylcarbamates and sulfamides derived from acetophenones.

In this study, several novel sulfamides were synthesized and evaluated for their acetylcholine esterase (AChE) and human carbonic anhydrase I, and II isoenzymes (hCA I and II) inhibition profiles. Reductive amination of methoxyacetophenones was used for the synthesis of amines. Amines were converted to sulfamoylcarbamates with chlorosulfonyl isocyanate (CSI) in the presence of BnOH. Pd-C catalyzed hydrogenolysis of sulfamoylcarbamates afforded sulfamides. These novel compounds were good inhibitors of the cytosolic hCA I, and hCA II with Ki values in the range of 45.9±8.9-687.5±84.3 pM for hCA I, and 48.80±8.2-672.2±71.9pM for hCA II. The inhibitory effects of the synthesized novel compounds on AChE were also investigated. The Ki values of these compounds were in the range of 4.52±0.61-38.28±6.84pM for AChE. These results show that hCA I, II, and AChE were effectively inhibited by the novel sulfamoylcarbamates 17-21 and sulfamide derivatives 22-26. All investigated compounds were docked within the active sites of the corresponding enzymes revealing the reasons of the effective inhibitory activity.