Design, synthesis, and biological activity studies on benzimidazole derivatives targeting myeloperoxidase.

Myeloperoxidase (MPO) plays a key role in human antimicrobial system by oxidizing vital molecules of microorganisms in phagolysosomes through produced hypochlorous acid (HOCl). However, MPO can be released outside the phagocyte and produces reactive intermediates leading to tissue damage. MPO, as a local mediator of tissue damage, has been associated with inflammatory diseases such as renal injury, multiple sclerosis, cardiovascular and neurodegenerative diseases. Therefore, the enzyme currently draws attention as a potential therapeutic target. In this study, isomeric 1,3-dihydro-2H-benzo[d]imidazole-2-thione derivatives having amide, hydrazide and hydroxamic acid groups either on nitrogen or on sulphur atom were designed and their inhibitory activity was determined on chlorination and peroxidation cycles of MPO. Among the compounds, 2-(2-thioxo-2,3-dihydro-1H-benzo[d]imidazole-1-yl)acetohydrazide(C19) was found as the most active inhibitor on both cycles.

Design, synthesis, spectroscopic characterizations, single crystal X-ray analysis, in vitro xanthine oxidase and acetylcholinesterase inhibitory evaluation as well as in silico evaluation of selenium-based N-heterocyclic carbene compounds.

Herein, eight new NHC-based selenourea derivatives were synthesized and characterized by using spectroscopic method (1H, 19F, and 13C NMR, FT-IR), and elemental analysis techniques. These compounds were synthesized by mixing benzimidazolium salts, potassium carbonate, and selenium powder in ethyl alcohol. Additionally, the molecular and crystal structures of the three compounds (1c, 2b, and 2c) were determined using the single-crystal x-ray diffraction (XRD) method. Diffraction analysis demonstrated the partial carbon-selenium double-bond character of these compounds. All compounds were determined to be highly potent inhibitors for AChE and XO enzymes. The IC50 values for the compounds were found in the range of 0.361-0.754 µM for XO and from 0.995 to 1.746 µM for AChE. The DNA binding properties of the compounds were investigated. These compounds did not have a remarkable DNA binding property. Also, DPPH radical scavenging activities of the compounds were also investigated. Compounds (1c), (2a), (3a), and (3b) exhibited more pronounced DPPH radical scavenging activity when compared to other compounds. Docking studies were applied by using AutoDock 4 to determine interaction mechanism of the selected compounds (1a), (1b), and (3b). The compound (1b) has good binding affinity (-9.78 kcal/mol) against AChE, and (-6.86 kcal/mol) for XO target. Drug similarity properties of these compounds compared to positive controls were estimated and evaluated by ADMET analysis. Furthermore, molecular dynamics simulations have been applied to understand the accuracy of docking studies. These findings and the defined compounds could be potential candidates for the discovery and progress of effective medicine(s) for AChE and XO in the future.Communicated by Ramaswamy H. Sarma.

Phthalimide-tethered imidazolium salts: Synthesis, characterization, enzyme inhibitory properties, and in silico studies.

A series of new imidazolium salts were prepared in good yield by the reaction between 1-alkylimidazole and a variety of alkyl halides. The structures of the compounds were identified by FT-IR, 1 H NMR, and 13 C NMR spectroscopy, elemental analysis, and mass spectrometry. The crystal structure of 1b was determined by the single-crystal X-ray diffraction method. The phthalimide-tethered imidazolium salts exhibited inhibition abilities toward acetylcholinesterase (AChE) and human carbonic anhydrases (hCAs) I and II, with Ki values in the range of 24.63 ± 3.45 to 305.51 ± 35.98 nM for AChE, 33.56 ± 3.71 to 218.01 ± 25.21 nM for hCA I and 17.75 ± 0.96 to 308.67 ± 13.73 nM for hCA II. The results showed that the new imidazolium salts can play a key role in the treatment of Alzheimer's disease, epilepsy, glaucoma, and leukemia, which is related to their inhibition abilities of hCA I, hCA II, and AChE. Molecular docking and in silico absorption, distribution, metabolism, excretion and toxicity studies were used to look into how the imidazolium salts interacted with the specific protein targets. To better visualize and understand the binding positions and the influence of the imidazolium salts on hCA I, hCA II, and AChE conformations, each one was subjected to molecular docking simulations.

New morpholine-liganded palladium(II) N-heterocyclic carbene complexes: Synthesis, characterization, crystal structure, and DNA-binding studies.

A series of the morpholine-liganded palladium(II) complexes (1a-e) bearing N-heterocyclic carbene (NHC) functionalized by benzonitrile were synthesized. These complexes were synthesized from (NHC)Pd(II)(pyridine) complexes (PEPPSI) and morpholine. The new complexes were fully characterized by using 1 H NMR, 13 C NMR, Fourier-transform infrared spectroscopy, and elemental analysis techniques. Single-crystal X-ray diffraction was used to determine the structure of a derivative. The DNA-binding studies of the new (NHC)Pd(II)morpholine complexes were examined using the pBR322 plasmid. The 2,4,6-trimethylbenzyl derivative compound has the most DNA binding activity. In addition, for the 3-methylbenzyl derivative compound, oxidation effects were observed at concentrations higher than 100 µg/ml. Also, the molecular and crystal structures of the complex 3-methylbenzyl derivative compound were recorded by using a single-crystal X-ray diffraction method.

meta-Cyanobenzyl substituted benzimidazolium salts: Synthesis, characterization, crystal structure and carbonic anhydrase, α-glycosidase, butyrylcholinesterase, and acetylcholinesterase inhibitory properties.

meta-Cyanobenzyl-substituted N-heterocyclic carbene (NHC) precursors were synthesized by the reaction of a series of N-(alkyl)benzimidazolium with 3-bromomethyl-benzonitrile. These benzimidazolium salts were characterized by using 1 H NMR, 13 C NMR, FTIR spectroscopy, and elemental analysis techniques. The molecular and crystal structures of 2f and 2g complexes were obtained by using the single-crystal X-ray diffraction method. The derivatives of these novel NHC precursors were effective inhibitors of α-glycosidase (AG), the cytosolic carbonic anhydrase I and II isoforms (hCA I and II), butyrylcholinesterase (BChE), and acetylcholinesterase (AChE) with Ki values in the range of 1.01-2.12 nM for AG, 189.56-402.44 nM for hCA I, 112.50-277.37 nM for hCA II, 95.45-352.58 nM for AChE, and 132.91-571.18 nM for BChE. In the last years, inhibition of the CA enzyme has been considered as a promising factor for pharmacologic intervention in a diversity of disturbances such as obesity, glaucoma, cancer, and epilepsy.

Spectroscopic, Structural and Density Functional Theory (DFT) Studies of Two Oxazol-5-one Derivatives.

In this study, two oxazol-5-one derivatives, C20H20N2O2 (1) and C21H22N2O2 (2), were synthesized by getting condensed p-N,N-diethylaminobenzaldehyde with two presented hippuric acid derivatives and in further studies they were analysed spectrochemically. Molecular and crystal structures of the compounds were determined by single-crystal X-ray diffraction and the results revealed that the molecular packing of the crystal structures were stabilized by weak intraand intermolecular interactions also with C-O∙∙∙π, C-H∙∙∙π and π∙∙∙π stacking interactions. Computational studies were also performed using DFT method at B3LYP/6-311G(d,p) level of theory. Vibrational modes and chemical shifts were calculated and compared with the experimental data. In addition, frontier molecular orbitals and molecular electrostatic potential surfaces were simulated. The calculated results show that the optimized geometries can well reproduce the crystal structure. Purpose of this study was to survey the effects of the reactants, which were condensed with each other to produce oxazol-5-one, upon the characteristic properties and crystal forms of the final oxazol-5-one.

Substituent position effect on the crystal structures of N-phenyl-2-phthalimidoethanesulfonamide derivatives.

In order to determine the impact of different substituents and their positions on intermolecular interactions and ultimately on the crystal packing, unsubstituted N-phenyl-2-phthalimidoethanesulfonamide, C16H14N2O4S, (I), and the N-(4-nitrophenyl)-, C16H13N3O6S, (II), N-(4-methoxyphenyl)-, C16H16N3O6S, (III), and N-(2-ethylphenyl)-, as the monohydrate, C18H18N2O4S·H2O, (IV), derivatives have been characterized by single-crystal X-ray crystallography. Sulfonamides (I) and (II) have triclinic crystal systems, while (III) and (IV) are monoclinic. Although the molecules differ from each other only with respect to small substituents and their positions, they crystallized in different space groups as a result of differing intra- and intermolecular hydrogen-bond interactions. The structures of (I), (II) and (III) are stabilized by intermolecular N-H...O and C-H...O hydrogen bonds, while that of (IV) is stabilized by intermolecular O-H...O and C-H...O hydrogen bonds. All four structures are of interest with respect to their biological activities and have been studied as part of a program to develop anticonvulsant drugs for the treatment of epilepsy.