Synthesis and anticholinesterase activity of fumaramide derivatives

Methanol as a Potential Hydrogen Source for Reduction Reactions Enabled by a Commercial Pt/C Catalyst

Catalytic reduction reactions using methanol as a transfer hydrogenating agent is gaining significant attention because this simple alcohol is inexpensive and produced on a bulk scale. Herein, we report the catalytic utilization of methanol as a hydrogen source for the reduction of different functional organic compounds such as nitroarenes, olefins, and carbonyl compounds. The key to the success of this transformation is the use of a commercially available Pt/C catalyst, which enabled the transfer hydrogenation of a series of simple and functionalized nitroarenes-to-anilines, alkenes-to-alkanes, and aldehydes-to-alcohols using methanol as both the solvent and hydrogen donor. The practicability of this Pt-based protocol is showcased by demonstrating catalyst recycling and reusability as well as reaction upscaling. In addition, the Pt/C catalytic system was also adaptable for the N-methylation and N-alkylation of anilines via the borrowing hydrogen process. This work provides a simple and flexible approach to prepare a variety of value-added products from readily available methanol, Pt/C, and other starting materials.

Design and Synthesis of Novel Dual Cholinesterase Inhibitors: In Vitro Inhibition Studies Supported with Molecular Docking

The major cholinesterase enzymes, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), are important in the therapy of Alzheimer's disease (AD) based on the cholinergic hypothesis. As a result, in recent years, the investigation of dual cholinesterase inhibition methods has become important among scientists. In this study, novel N-(4-chlorobenzyl)-3,4-dimethoxy-N-(m-substituted)benzamide derivatives were synthesized. Then, inhibitory properties of these derivatives were examined in human AChE and BuChE in vitro and possible interactions were determined by molecular docking studies. All benzamide derivatives were exhibited dual inhibitory character and high BBB permeability. The most effective inhibitor was found as N7 for both AChE and BuChE with IC₅₀ values of 1.57 and 2.85 μM, respectively. Besides the most potent inhibitor was predicted as N7 in terms of binding energies with -12.18 kcal/mol and -9.92 kcal/mol, respectively. The reason for these results is that bromine (N7) is the bulkiest molecule among the other substituted groups. These derivatives could be exploited to develop new medications for the treatment of central nervous system-related diseases as AD by acting as dual inhibitors of AChE and BChE.

Synthesis and in silico studies of triazene-substituted sulfamerazine derivatives as acetylcholinesterase and carbonic anhydrases inhibitors

A novel series of sulfonamides, 4-(3-phenyltriaz-1-en-1-yl)-N-(4-methyl-2-pyrimidinyl)benzenesulfonamides (1-9), was designed and synthesized by the diazo reaction between sulfamerazine and substituted aromatic amines for the first time. Their chemical structures were characterized by ¹ H nuclear magnetic resonance (NMR), ¹³ C NMR, and high-resolution mass spectra. The newly synthesized compounds were evaluated in terms of acetylcholineasterase (AChE) and human carbonic anhydrases (hCA) I and II isoenzymes inhibitory activities. According to the AChE inhibition results, the K_i values of the compounds 1-9 were in the range of 19.9 ± 1.5 to 96.5 ± 20.7 nM against AChE. Tacrine was used as the reference drug and its K_i value was 49.2 ± 2.7 nM against AChE. The K_i values of the compounds 1-9 were in the range of 10.2 ± 2.6 to 101.4 ± 27.8 nM against hCA I, whereas they were 18.3 ± 4.4 to 48.1 ± 4.5 nM against hCA II. Acetazolamide was used as a reference drug and its K_i values were 72.2 ± 5.4 and 52.2 ± 5.7 nM against hCA I and hCA II, respectively. The most active compounds, 1 (nonsubstituted) against AChE, 5 (4-ethoxy-substituted) against hCA I, and 8 (4-bromo-substituted) against hCA II, were chosen and docked at the binding sites of these enzymes to explain the inhibitory activities of the series. The newly synthesized compounds presented satisfactory pharmacokinetic properties via the estimation of ADME properties.

New multitarget directed benzimidazole-2-thiol-based heterocycles as prospective anti-radical and anti-Alzheimer's agents

A series of new heterocycles (4-18) was synthesized by the structural modification of benzimidazole-2-thiol (BT, 2-MBI). The structures of the synthesized compounds were confirmed with the help of high-resolution mass spectrometry (HRMS) and ¹ HNMR spectroscopy. High inhibitions of the oxidants such as ABTS and DPPH were observed for compounds 9 [IC₅₀ (s) = 167.4 μM (ABTS), 139.5 μM (DPPH)], 10 [IC₅₀ (s) = 186.5 μM (ABTS), 155.4 μM (DPPH)], 11 [IC₅₀ (s) = 286.1 μM (ABTS), 189.1 μM (DPPH)], 12 [IC₅₀ (s) = 310.8 μM (ABTS), 162.2 μM (DPPH)], 14 [IC₅₀ (s) = 281.3 μM (ABTS), 205.7 μM (DPPH)], 15 [IC₅₀ (s) = 284.1 μM (ABTS), 177.3 μM (DPPH)], and 16 [IC₅₀ (s) = 344.7 μM (ABTS), 270.2 μM (DPPH)] as compared with Ascorbic acid [IC₅₀ (s) = 340.9 μM (ABTS), 164.3 μM (DPPH)]. The anti-Alzheimer's activity was performed in vitro against cholinesterase enzymes (AChE, BChE). Compound 11 was able to show significant inhibitions [IC₅₀ (s) = 121.2 μM (AChE), 38.3 μM (BChE)] as against that of galantamine [IC₅₀ (s) = 139.4 μM (AChE), 40.3 μM (BChE)]. Compound 14 was found as a very good inhibitor of butyrylcholinesterase (IC₅₀ = 35.4 μM) as compared with standard galantamine. Molecular docking was further performed to investigate the mechanism of anticholinesterase activity.

Synthesis, cytotoxicities, and carbonic anhydrase inhibition potential of 6-(3-aryl-2-propenoyl)-2(3H)-benzoxazolones

In this study, new chalcone compounds having the chemical structure of 6-(3-aryl-2-propenoyl)-2(3H)-benzoxazolones (1-8) were synthesised and were characterised by 1H-NMR, 13 C-NMR, and HRMS spectra. Cytotoxic and carbonic anhydrase (CA) inhibitory effects of the compounds were investigated. Cytotoxicity results pointed out that compound 4, 6-[3-(4-trifluoromethylphenyl)-2-propenoyl]-3H-benzoxazol-2-one, showed the highest cytotoxicity (CC50) and potency-selectivity expression (PSE) value, and thus can be considered as a lead compound of this study. According to the CA inhibitory results, IC50 values of the compounds 1-8 towards hCA I were in the range of 29.74-69.57 µM, while they were in the range of 18.14 - 48.46 µM towards hCA II isoenzyme. Ki values of the compounds 1-8 towards hCA I were in the range of 28.37 ± 6.63-70.58 ± 6.67 µM towards hCA I isoenzyme and they were in the range of 10.85 ± 2.14 - 37.96 ± 2.36 µM towards hCA II isoenzyme.

Copper-catalyzed intermolecular C(sp3)-H bond functionalization towards the synthesis of tertiary carbamates

We describe the development of an intermolecular unactivated C(sp3)-H bond functionalization towards the direct synthesis of tertiary carbamates. The transformation proceeded using a readily available, abundant first-row transition metal catalyst (copper), and isocyanates as the source of the amide moiety. This is a novel strategy for direct transformation of a variety of unactivated hydrocarbon feedstocks to N-alkyl-N-aryl and N,N-dialkyl carbamates without pre-functionalization or installation of a directing group. The reaction had a broad substrate scope with 3° > 2° > 1° site selectivity. The reaction proceeded even on a gram scale, and a corresponding free amine was directly obtained when the reaction was performed at high temperature. Kinetic studies suggested that radical-mediated C(sp3)-H bond cleavage was the rate-determining step.

Preparation, anticholinesterase activity, and docking study of new 2-butenediamide and oxalamide derivatives

Several new oxalamide and 2-butenediamide derivatives have been designed, synthesized and evaluated as the acetyl- and butyryl-cholinesterase inhibitors for Alzheimer's disease. The enzyme inhibitory activity of the synthesized compounds was measured using Ellman's colorimetric method. It was revealed that compound 1a (N,N'-bis-(4-chloro-benzyl)-N,N'-diphenyl-oxalamide) showed maximum activity against BuChE with a half maximal inhibitory concentration (IC50) = 1.86 µM and compound 2a (but-2-enedioic acid bis-[(4-chloro-benzyl)-phenyl-amide]) exhibited optimum AChE (IC50 = 1.51 µM) inhibition with a high-selectivity index. To better understand the enzyme-inhibitor interaction of the most active compounds towards cholinesterase, molecular modelling studies were carried out. Docking simulations revealed that inhibitors 1a and 2a targeted both the catalytic active site and the peripheral anionic site of 1ACJ and 1P0I.