Nickel Ferrite (NiFe2O4) Nanoparticles as Magnetically Recyclable Nanocatalyst for Highly Efficient Synthesis of 4H-Chromene Derivatives.

An adapted one-pot route to nanocatalyst-assisted synthesis of 4H-chromenes via three component condensation reaction between dimedone, malononitrile, and a broad range of aryl aldehydes by the use of magnetic nickel ferrite nanoparticles is described. By this achievement, not only a novel route to highly efficient synthesis of these series of heterocycles was introduced but also the scope of these medicinally important products was developed via preparation of some novel products. Above all, a new application of nickel ferrite nanoparticles (NiFe2O4 NPs) as highly efficient, green and magnetically recyclable catalyst has been introduced. Overall, obtaining good to excellent yields of products, environmentally and economic benign procedure, easy handling, availability of starting materials, use of non-toxic solvents, and high recyclability of nano-catalyst could be countered as most important advantages of this methodology.

Phenoxyethyl Piperidine/Morpholine Derivatives as PAS and CAS Inhibitors of Cholinesterases: Insights for Future Drug Design.

Acetylcholinesterase (AChE) catalyzes the conversion of Aß peptide to its aggregated form and the peripheral anionic site (PAS) of AChE is mainly involved in this phenomenon. Also catalytic active site (CAS) of donepezil stimulates the break-down of acetylcholine (ACh) and depletion of ACh in cholinergic synapses are well established in brains of patients with AD. In this study, a set of compounds bearing phenoxyethyl amines were synthesized and their inhibitory activity toward electric eel AChE (eeAChE) and equine butyrylcholinesterase (eqBuChE) were evaluated. Molecular dynamics (MD) was employed to record the binding interactions of best compounds against human cholinesterases (hAChE and hBuChE) as well as donepezil as reference drug. In vitro results revealed that compound 5c is capable of inhibiting eeAChE activity at IC50 of 0.50 µM while no inhibitory activity was found for eqBuChE for up to 100 µM concentrations. Compound 5c, also due to its facile synthesis, small structure and high selectivity for eeAChE would be very interesting candidate in forthcoming studies. The main interacting parts of compound 5c and compound 7c (most potent eeAChE and eqBuChE inhibitors respectively) with receptors which confer selectivity for AChE and BuChE inhibition were identified, discussed, and compared with donepezil's interactions. Also during MD simulation it was discovered for the first time that binding of substrates like donepezil to dual CAS and PAS or solely CAS region might have a suppressive impact on 4-α-helical bundles near the tryptophan amphiphilic tetramerization (WAT) domain of AChE and residues which are far away from AChE active site. The results proposed that residues involved in donepezil interactions (Trp86 and Phe295) which are located in CAS and mid-gorge are the mediator of conformational changes in whole protein structure.

Synthesis, and molecular modeling of bis(3-(piperazine-1-yl)propyl)tungstate (BPPT) nanoparticles, and its first catalytic application for one-pot synthesis of 4H-chromene derivatives.

A novel, nano-sized, bis(3-(piperazine-1-yl)propyl)tungstate (BPPT) is introduced as an efficient and reusable organometallic catalyst which is considered as a heterogeneous Bronsted-Lowry base and applied successfully for one-pot synthesis of methyl 2-amino-4-aryl substituted-4H-chromene derivatives with good to excellent yields. BPPT has been prepared via a two-step route from natrium tungstate salt. At first, the oxygens of Na2WO4 react with 1-bromo-3-chloropropane via nucleophilic substitution to produce bis(3-choloro propyl)tungstate. Then nucleophilic substitution of piperazine with chlorines produced bis(3-(piperazine-1-yl)propyl) tungstate. Bis(3-(piperazine-1-yl)propyl) tungstate, which was called BPPT, characterized by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM) and scanning electron microscope (SEM). The catalyst is heterogeneous, green and recyclable. It is a thermally stable and its handling is easy. Its catalytic activity is very high and leads to the production of 4H-pyran derivatives with good to excellent yields in short reaction times. Furthermore, molecular modeling studies and ADMETox prediction revealed that not only it can inhibit acetylcholinesterase enzyme and act as an anti-Alzheimer agent but also has no variation from Lipinski's rule of five and can be a good candidate as anti-Alzheimer agents. These above-mentioned facts can be countered as advantages of the current protocol.

Highly Significant Scaffolds to Design and Synthesis Cholinesterase Inhibitors as Anti-Alzheimer Agents.

Alzheimer, a progressive disease, is a common term for memory loss which interferes with daily life through severe influence on cognitive abilities. Based on the cholinergic hypothesis, and Xray crystallographic determination of the structure of acetylcholinesterase (AChE) enzyme, the level of acetylcholine (ACh, an important neurotransmitter associated with memory) in the hippocampus and cortex area of the brain has a direct effect on Alzheimer. This fact encourages scientists to design and synthesize a wide range of acetylcholinesterase inhibitors (AChEIs) to control the level of ACh in the brain, keeping in view the crystallographic structure of AChE enzyme and drugs approved by the Food and Drug Administration (FDA). AChEIs have slightly diverse pharmacological properties, but all of them work by inhibiting the segregation of ACh by blocking AChE. We reviewed significant scaffolds introduced as AChEIs. In some studies, the activity against butyrylcholinesterase (BuChE) has been evaluated as well because BuChE is a similar enzyme to neuronal acetylcholinesterase and is capable of hydrolyzing ACh. In order to study AChEIs effectively, we divided them structurally into 12 classes and briefly explained effective AChEIs and compared their activities against AChE enzyme.

Magnetically retrievable ferrite nanoparticles in the catalysis application.

In the present review, we summarized the applications of magnetic spinel ferrite nanoparticles as catalysts in organic reactions and transformations. Catalytic applications are comprised of using mostly cobalt, nickel, copper, and zinc ferrites, along with their mixed-metal combinations based on nano ferrites. The spinel ferrites (SFs) are gained principally by wet-chemical, sol-gel or co-precipitation methods, more infrequently by the mechanical high-energy ball milling, spark plasma sintering, sonochemical technique, microwave heating or hydrothermal route. Catalytic processes with the application of ferrite nanoparticles are included decomposition (in particular photocatalytic), reactions of dehydrogenation, oxidation, alkylation, CC coupling, removing organic/inorganic contaminants from aqueous solutions. As significant and remarkable advantages, ferrite nanocatalysts not only are environmentally benign and compatible with green chemistry aspects but also can be simply recovered from reaction systems and recycled up to several times almost without significant loss of their catalytic activity.

Design, synthesis, biological evaluation, and molecular dynamics of novel cholinesterase inhibitors as anti-Alzheimer's agents.

A series of novel chroman-4-one derivatives were designed and synthesized successfully with good to excellent yield (3a-l). In addition, the obtained products were evaluated for their cholinesterase (ChE) inhibitory activities. The results show that among the various synthesized compounds, analogs bearing the piperidinyl ethoxy side chain with 4-hydroxybenzylidene on the 3-positions of chroman-4-one (3l) showed the most potent activity with respect to acetylcholinesterase (anti-AChE activity; IC50 = 1.18 µM). In addition, the structure-activity relationship was studied and the results revealed that the electron-donating groups on the aryl ring of the 3-benzylidene fragment (3k, 3l) resulted in the designed compounds to be more potent ChE inhibitors in comparison with those having electron-withdrawing groups (3h). In this category, the strongest ChE inhibition was found for the compound containing piperidine as cyclic amine, and a hydroxyl group (for AChE, compound 3l) and fluoro group (for butyrylcholinesterase (BuChE, compound 3i) on the para-position of the aryl ring of the benzylidene group. The molecular docking and dynamics studies of the most potent compounds (3i and 3l against BuChE and AChE, respectively) demonstrated remarkable interactions with the binding pockets of the ChE enzymes and confirmed the results obtained through in vitro experiments.

Synthesis, biological evaluation, and computational studies of novel fused six-membered O-containing heterocycles as potential acetylcholinesterase inhibitors.

An efficient, borax-catalyzed protocol for the synthesis of novel 4-aryl-substituted-4H-pyran derivatives fused to α-pyrone ring in a one-pot is described. By this achievement, some novel 4-aryl substituted 4H-pyrans fused to the α-pyrone ring as potential acetylcholinesterase inhibitors (AChEIs) with good to excellent yields are obtained from a one-pot three-component reaction between various aryl aldehydes, 4-hydroxy-6-methyl-2H-pyran-2-one and malononitrile. The method is a facile, inexpensive, practical and highly efficient one to obtain target compounds. The chemical structures of all compounds were characterized by FT-IR, FT-13CNMR and FT-1HNMR, MS spectroscopy and also elemental analyses data. Furthermore, the purity of all novel compounds was checked by HPLC. In addition, both molecular modelling studies and Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMETox) prediction nominated all compounds as good acetylcholinesterase inhibitors to the potential treatment of Alzheimer, Parkinson and Autism diseases that among them compound 4f showed the best activity against acetylcholinesterase enzyme.

Molybdenum Oxide Nanoparticles as Recyclable Heterogeneous Catalyst for Synthesis of Arylidene Ethyl Cyanoacetates.

This work reports an adapted route to the highly efficient synthesis of arylidene ethyl cyanoacetate derivatives in the presence of catalytic amounts of molybdenum oxide nanoparticles (MoO3 NPs) under green conditions at ambient temperature. From the reaction, a wide range of novel arylidene ethyl cyanoacetates was successfully synthesized with high yields from the Knoevenagel condensation reaction between various aryl aldehydes and ethyl cyanoacetate in the presence of MoO3 nanoparticles. The capability of catalyst to separate from the reaction mixture and then reuse is another advantage of this reaction. Furthermore, obtained products belong to analogous of organic compounds that have shown biological activity, and can be used pharmaceutics.

A Green One-Pot Synthesis of 4-Hydroxychromenylarylmethyl- 6-Hydroxypyrimidine-2,4-Diones Using Titanium Dioxide Nanowires as an Effective and Recyclable Catalyst.

AIM AND OBJECTIVE: Since a wide range of biological and pharmaceutical activities of barbituric acid, 4-hydroxycoumarin and their derivatives have been disclosed until now, in the domain of our interest to find newly catalytic routes for highly efficient synthesis of potentially interesting biologically active organic compounds, and extension of their areas, herein we introduce a three component combinatorial reaction based on (N,N-dimethyl)barbituric acid and 4- hydroxycoumarin scaffolds. MATERIAL AND METHOD: All starting materials were purchased from Merck chemical company and were applied without further purifications. Catalytic reaction between barbituric acid (or N,N-dimethyl barbituric acid), 4-hydroxycoumarin, and a wide range of aryl aldehydes by employing titanium dioxide nanowires (TiO2 NWs) is successfully performed under solvent-free conditions at 100 °C, and led efficiently to obtain target products. RESULTS: From loading above mentioned three component reaction, starting materials in the presence of catalytic amounts of TiO2 NWs as a key factor were condensed together via three C-C bond formation to obtain 12 newly prepared compounds. This procedure profits some advantages such as an efficiency, environmental safety and high recyclability of nano-catalyst. CONCLUSION: In this work, by the use of a green adapted method in a condensation three component reaction catalyzed by TiO2 NWs as an efficient nano-catalyst, some newly prepared products were prepared in a one pot, and the scope of potentially interesting biologically active organic compounds which can be duly considered by biologists and pharmacologists was developed.