Spectroscopic characterization of hydroxyquinoline derivatives with bromine and iodine atoms and theoretical investigation by DFT calculations, MD simulations and molecular docking studies

Synthesis, characterization, molecular docking and molecular dynamics simulations of novel 2,5-disubstituted-1,3,4-thiadiazole derivatives as potential cholinesterase/monoamine oxidase dual inhibitors for Alzheimer's disease

Designing multi-targeted drugs (MTD) for Alzheimer's disease (AD) is now one of the priorities for medicinal chemists, as the disease has a complicated not fully understood pathological nature and the approved mono-targeted drugs only alleviate the symptoms. In this study, the synthesis, spectral analyses and in vitro inhibition activity against cholinesterase (ChE) and monoamine oxidase (MAO) enzymes of a novel series of N-[5-(adamantan-1-yl)-1,3,4-thiadiazol-2-yl]-2-(4-un/substituted) cyclic secondary amino-acetamide/propanamide derivatives were done. Generally, derivatives were more selective against acetylcholinesterase (AChE) and h-MAO-B than butyrylcholinesterase (BChE) and h-MAO-A, respectively. Derivatives 4a, 4b, 3a, 3d and 3b ordered from the most potent to the least displayed significant inhibition against AChE. Also, derivatives 4a, 4b and 3a still maintained their significant inhibition against h-MAO-B in the same potency order, making them dual inhibitors and MTD candidates for AD. Binding interactions with several crucial amino acid residues for activity and selectivity as well as the stability of the most active derivatives-enzyme complex were confirmed utilizing molecular docking and molecular dynamic simulation studies.Communicated by Ramaswamy H. Sarma.

Synthesis and Anticancer Activities of Pyrazole-Thiadiazole-Based EGFR Inhibitors

Lung cancer is one of the most common cancer types of cancer with the highest mortality rates. However, while epidermal growth factor receptor (EGFR) is an important parameter for lung cancer, EGFR inhibitors also show great promise in the treatment of the disease. Therefore, a series of new EGFR inhibitor candidates containing thiadiazole and pyrazole rings have been developed. The activities of the synthesized compounds were elucidated by in vitro MTT, (which is chemically 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), cytotoxicity assay, analysis of mitochondrial membrane potential (MMP) by flow cytometry, and EGFR inhibition experiments. Molecular docking and molecular dynamics simulations were performed as in silico studies. Compounds 6d, 6g, and 6j showed inhibitor activity against the A549 cell line with IC50 = 5.176 ± 0.164; 1.537 ± 0.097; and 8.493 ± 0.667 μM values, respectively. As a result of MMP by flow cytometry, compound 6g showed 80.93% mitochondrial membrane potential. According to the results of the obtained EGFR inhibitory assay, compound 6g shows inhibitory activity on the EGFR enzyme with a value of IC50 = 0.024 ± 0.002 μM.

Synthesis, Antifungal Activities, Molecular Docking and Molecular Dynamic Studies of Novel Quinoxaline-Triazole Compounds

Uncontrolled use of antifungal drugs affects the development of resistance to existing drugs. Azole antifungals constitute a large part of antifungal therapy. Therefore, there is a need for new azole antifungals. Within the scope of this study, 17 new triazole derivative compounds were synthesized. Structure determinations were clarified by spectroscopic analysis methods (¹H-NMR, ¹³C-NMR, HRMS). In addition, structure matching was completed using two-dimensional NMR techniques, HSQC, HMBC and NOESY. The antifungal effects of the compounds were evaluated on Candida strains by means of in vitro method. Compound 5d showed activity against Candida glabrata with a MIC₉₀ = 2 μg/mL. Compound 5d showed activity against Candida krusei with a MIC₉₀ = 2 μg/mL. This activity value, which is higher than fluconazole, is promising. In addition, the biofilm inhibition percentages of the compounds were calculated. Molecular docking and molecular dynamics simulations performed with compound 5d are in harmony with activity studies.

Antidepressant-like effect of tofisopam in mice: A behavioural, molecular docking and MD simulation study

BACKGROUND

Depression is a disease that affects millions of people worldwide, and the discovery and development of effective and safe antidepressant drugs is one of the important topics of psychopharmacology.

OBJECTIVES

In this study, it was aimed to investigate the antidepressant-like activity potential of tofisopam, an anxiolytic drug with 2,3-benzodiazepine structure, and to elucidate the pharmacological mechanisms mediating this effect.

METHODS

The antidepressant-like activity of tofisopam was investigated using tail suspension and modified forced swimming tests. Possible interactions of tofisopam with µ- and δ-opioid receptor subtypes were clarified by pharmacological antagonism, molecular docking and molecular dynamics simulation studies.

RESULTS

Tofisopam (50 and 100 mg/kg) significantly shortened the immobility time of mice in both the tail suspension and the modified forced swimming tests. The drug, at the same doses, prolonged the duration of swimming and climbing behaviours measured in modified forced swimming tests. A dosage of 25 mg/kg was ineffective. Mechanistic studies showed that the pretreatment with p-chlorophenylalanine methyl ester (serotonin synthesis inhibitor; 4 consecutive days, 100 mg/kg), α-methyl-para-tyrosine methyl ester (catecholamine synthesis inhibitor; 100 mg/kg), naloxonazine (selective µ-opioid receptor blocker, 7 mg/kg) and naltrindole (a selective δ-opioid receptor blocker, 0.99 mg/kg) abolished the anti-immobility effect induced by the 50 mg/kg dose of tofisopam in the tail suspension tests. Our in silico studies supported the behavioural findings that the antidepressant-like effect of tofisopam is mediated by μ- and δ-opioid receptors.

CONCLUSION

This study is the first to show that tofisopam has antidepressant-like activity mediated by the serotonergic, catecholaminergic and opioidergic systems.

A foundational theoreticalAl12E12(E = N, P) adsorption and quinolone docking study: cage–quinolone pairs, optics and possible therapeutic and diagnostic applications

This combined Al₁₂E₁₂ (E = N, P) surface adsorption and docking study describes the new possibility of prospective potential probing(photophysical/optical) and therapy(medicinal/biochemical) with these adsorbent conjugates. DFT investigations were undertaken herein to help generate geometrical models and better understand the possible favorable adsorption energetics. We attempt to explain their adsorption behaviors and docking involving SARS-CoV-2 viruses (PDB)to assess their possible pharmaceutical potential against the pandemic virus (COVID-19). The adsorption behavior of 8-hydroxy-2-methylquinoline (MQ) and its halogenated derivatives, 5,7-diiodo-8-hydroxy-2-methylquinoline (MQI), 5,7-dichloro-8-hydroxy-2-methylquinoline (MQCl), and 5,7-dibromo-8-hydroxy-2-methylquinoline (MQBr), with aluminum-nitrogen (AlN), and aluminum-phosphorous (AlP) fullerene-like nanocages is reported. A decrease in the hardness of the nanoclusters when adsorbed with drug molecules resulted in an incrementally improved chemical softness (see e.g., Hard-Soft Acid Base theory) indicating that reactivity of the drug molecule in the resulting complex increases upon cluster chemical adsorption. The energy gap is found to be maximized for AlN-MQ and minimized for AlP-MQI; the reduced density gradient (RDG) iso-surfaces and AIM studies also corroborated this. Therefore, these two were found, respectively, to be the least and most electrically conductive of the species under study. We selected a simple medicinal building block (chelator)in addition to selecting the cluster based on previous literature reports. Important parameters such as gap energies and global indices were determined. We assessed NLO properties. The SARS-CoV-2 virus PDB docking data for 6VW1, 6VYO, 6WKQ, 7AD1, 7AOL, 7B3C, were enlisted as ligand targets for studies of docking (PatchDock Server) using the requisite PDB geometries (For the structure of 6VW1, kindly see reference, 2020; For the structure of 6VYO kindly see reference, 2020; For the structure of 6WKQ kindly see reference, 2020; For the structure of 7AD1 kindly see reference, 2021; For the structure of 7AOL kindly see reference, 2021; For the structure of 7B3C kindly see reference, 2021). Such findings indicate that the AlN-drug conjugation have inhibitory effect against these selected receptors.Communicated by Ramaswamy H. Sarma.

Design, synthesis, biological activity, molecular docking, and molecular dynamics of novel benzimidazole derivatives as potential AChE/MAO-B dual inhibitors

To develop new acetylcholinesterase (AChE)-monoamine oxidase-B (MAO-B) dual inhibitors against Alzheimer's disease, the benzimidazole ring, which has a propargyl side chain with previously proven selective MAO-B inhibitory activity, was used as the main structure. Moreover, like donepezil, it was thought that the enzyme AChE would provide π-π interactions with the peripheral anionic side in this structure. Piperazine derivatives were chosen for the cationic active site. The synthesis of the compounds was carried out in five steps. The structures of the compounds were determined using ¹ H-NMR (nuclear magnetic resonance), ¹³ C-NMR, and high-resolution mass spectrometry spectroscopic methods. First, the in vitro AChE, butyrylcholinesterase (BChE), MAO-A, and MAO-B inhibitory potentials of the obtained compounds were investigated. As a result of activity tests, compounds 5b, 5e, 5g, and 5h showed inhibitory activity against AChE; compounds 5e and 5g showed inhibitory activity against MAO-B. None of the compounds showed inhibitory activity against BChE or MAO-A. Compounds 5e and 5g showed dual inhibition. Among these compounds, compound 5g had inhibition potential similar to that of donepezil and selegiline. For compound 5g, further kinetic studies and Aβ-plaque inhibitory potentials were investigated using in vitro methods. Molecular docking studies were performed using both AChE and hMAO-B crystals to elucidate the compound's interactions with the enzyme active site. The binding modes of the compound on AChE were fully elucidated by molecular dynamics studies.

Structural, Electronic and NLO Properties of 6-aminoquinoline: A DFT/TD-DFT Study

A computational study based on the DFT/TD-DFT approach was performed to explore various properties of 6-aminoquinoline (6AQ). The geometrical parameters, molecular orbitals (MOs), electronic spectra, electrostatic potential, molecular surface, reactivity parameters and thermodynamic properties of 6AQ were explored. The absorption and emission spectra of 6AQ in solvents have been estimated by TD-DFT coupled with the PCM model and correlated with the available experimental results. Depending on the solvents, the computed absorption maxima of 6AQ were noticed between 327 nm - 340 nm and ascribed to [Formula: see text] transition. The simulated emission maxima were obtained between 389 to 407 nm and ascribed to [Formula: see text] transition. On increasing the solvent polarity, both the emission and absorption maxima showed a bathochromic shift. The LUMO and HOMO were localized on the entire molecule. It was observed that the lowest excited state is possibly the [Formula: see text] charge-transfer (CT) state. The natural bonding orbital (NBO) study points out that ICT plays a significant role in stabilizing the molecular system. Moreover, the NLO (nonlinear optical) properties (polarizability, first-order hyperpolarizability and dipole moment) were computed using different hybrid functionals. The estimated values indicate that 6AQ can be considered a desirable molecule for further studies of the NLO applications.

Vibrational spectroscopy, quantum computational and molecular docking studies on 2-chloroquinoline-3-carboxaldehyde

The quantum mechanical density functional theory (DFT) approach was used to analyze vibrational spectroscopy for the title compound 2-chloroquinoline-3-carboxaldehyde, and the observations were compared to experimental results. B3LYP with the 6-311++ G (d, p) basis set produces the optimized molecular structure and vibrational assignments. The charge delocalization and hyper conjugative interactions were studied using NBO analysis. Fukui functions were used to determine the chemical reactivity of the examined molecule. The linear polarizability, first order polarizability, NLO and Thermodynamic properties are calculated. Additionally, Molecular electrostatic potential (MEP) and HOMO-LUMO are reported. Multi wavefunction analysis like ELF (Electron Localization Function) and LOL (Localized Orbital Locator) are analyzed. For the headline compound, drug-likeness properties were examined. Molecular docking analysis on the examined molecule are done to understand the biological functions of the headline molecule and the minimum binding energy, hydrogen bond interactions, are analyzed.

Spectroscopic investigations, concentration dependent SERS, and molecular docking studies of a benzoic acid derivative

Spectroscopic analysis, density functional theory (DFT) studies and surface enhanced Raman scattering of 4-((3-bromo-5-chloro-2-hydroxybenzylidene)amino)benzoic acid (BCHB) have been studied on different silver colloids concentrations in order to know the particular chemical species responsible for the spectra. For Raman and surface enhanced Raman scattering (SERS) wavenumbers, changes are observed. Observed variations in the modes of ring may be due to interaction of the π-electrons and presence of this indicated that RingII is more inclined than RingI and the BCHB assumes inclined orientation for concentration 10^-3 M. Changes in orientation are seen in SERS spectra depending on concentration. In order to determine the electron-rich and poor sites of BCHB, the molecular electrostatic potential was also constructed. The molecular docking studies show that the bindings and interactions with the receptors may be supporting evidence for further studies in design further BCHB pharmaceutical applications.