Towards more effective acetylcholinesterase inhibitors: a comprehensive modelling study based on human acetylcholinesterase protein–drug complex

Queuine as a potential multi-target drug for alzheimer's disease: insights from protein dynamics

Alzheimer's disease (AD) is a neurodegenerative disorder with a complex pathogenesis. One promising approach to treating AD is simultaneously targeting multiple aspects of the disease using a multi-target drug (MTD). In this study, multi-target drug (MTD) potential of the nutraceutical molecule Queuine was explored using molecular docking and molecular dynamics (MD) simulations with five different protein targets engaged in AD: AChE, beta-site amyloid precursor protein cleaving enzyme-1 (BACE-1), N-methyl-D-aspartate receptor (NMDAR), monoamine oxidase A (MAO-A), and Synapsin III. Queuine revealed significant binding affinities, the docking scores being -10.1, -5.97, -5.63, -8.40, and -10.56 kcal/mol for AChE, BACE-1, NMDAR, MAO-A, and Synapsin III, respectively. MD simulations showed that Queuine formed stable complexes and preserved its stability throughout the simulation, the backbone fluctuations remaining within 2.5 Å specifically in the case of the BACE-1. Elastic network model simulations and principal component analysis were carried out to illustrate the dynamics of the protein systems. Significant hinge-bending and twisting-type motions that may be relevant to function were observed around the dimerization interfaces or binding sites. Structural clustering based on PCA analysis and cross-correlation maps demonstrated that Queuine binding altered the protein dynamics more drastically in the case of highly mobile proteins NMDAR and MAO-A. We propose that the neuroprotective effect of Queuine may stem from its prominent inhibitory action on enzymes BACE-1 and AChE. Our results suggest that Queuine may serve as a promising MTD candidate for the treatment of AD.Communicated by Ramaswamy H. Sarma.

Synthesis, biological evaluation and molecular docking studies of novel 1,3,4-thiadiazoles as potential anticancer agents and human carbonic anhydrase inhibitors

Thiosemicarbazide and also 1,3,4-thiadiazole derivatives have been garnering substantial attention from researchers worldwide due to their expansive range of biological activities, encompassing antimicrobial, anti-inflammatory, and anticancer properties. Herein, we embarked on a comprehensive investigation in this study, introducing a novel series of thiosemicarbazides (3a-3i) and their corresponding 1,3,4-thiadiazole (4a-4i) derivatives. The compounds were meticulously designed, synthesized, and subjected to meticulous characterization using various spectroscopic methods such as FT-IR, 1H-NMR, 13C-NMR, and elemental analysis. Afterward, their potential anti-proliferative effectiveness was assessed using MTT assay against two cancer cell lines (U87 and HeLa) and normal fibroblast cells (L929). Among the compounds, 4d showed the highest cytotoxic activity against U87 and 4i against HeLa. Compound 3b exhibited selective cytotoxic activity against both cancer cells. Among the molecules with selective activity against the U87 cell line; 3a, 3b, 4d and 4e were further evaluated by caspase-3 activity levels, Bax and Bcl-2 protein expression, and total oxidant status assay. Besides, carbonic anhydrase IX activity studies were also performed in order to understand the underlying mechanism of action. The results indicated that compound 4e showed higher efficacy than standard acetazolamide (IC50 = 0.58 ± 0.02 µM) with an IC50 value of 0.03 ± 0.01 µM. Furthermore, molecular docking studies were carried out using carbonic anhydrase IX crystals to determine the compound's interactions with the enzyme's active sites. This comprehensive investigation sheds light on the intricate interplay between molecular structure and biological activity, providing valuable insights into the therapeutic potential of these compounds.

Identification of selective inhibitors for phosphodiesterase 5A using e-pharmacophore modelling and large-scale virtual screening-based structure guided drug discovery approaches

The inhibition of Phosphodiesterase 5A (PDEA5) has the potential to modulate pulmonary arterial hypertension and cardiovascular diseases. Exploring the cross-reactivity of clinically available PDE5A therapeutics with PDE6A is intriguing in order to develop highly selective PDE5A compounds in cardiovascular arena. In the current study, we leveraged e-pharmacophore based screening and molecular dynamics (MD) simulation to discover more selective PDE5A inhibitors as compared to the PDE6A catalytic domain. e-Pharmacophore based mapping of the CoCoCo database (7 million compounds: ∼ 150,000,000 conformers), followed by Glide docking, MM-GBSA, and protein-inhibitor interaction analysis, revealed 1536427, 4832637 and 6788240 as stable, tight binders of PDE5A instead of PDE6A. These compounds adhere to Lipinski Rule of Five (RO5) and ADME/Tox criteria. MD simulations analysis showed that 1536427 stays stable and tightly binds to catalytic (Q-region) core of PDE5A catalytic domain as compared to sildenafil. Pronounced inward motions of the hydrophobic (H-region) and Lid region indicate the closure of PDE5A-1536427 complex, whereas this region in PDE6A-1536427 is more open. Significant differences in the interactions, stability, and dynamics of 1536427 were observed in the catalytic domain of PDE6A, demonstrating less specificity for PDE6A in comparison to PDE5A. After lead optimization and therapeutic interventions, this proposed lead may emerge as a promising PDE5A selective inhibitor.Communicated by Ramaswamy H. Sarma.

Novel beta-lactam substituted benzenesulfonamides: in vitro enzyme inhibition, cytotoxic activity and in silico interactions

In this study, a library of twelve beta-lactam-substituted benzenesulfonamides (5a-l) was synthesized using the tail-approach method. The compounds were characterized using IR, 1H NMR, 13C NMR and elemental analysis techniques. These newly synthesized compounds were tested for their ability to inhibit the activity of two carbonic anhydrases (hCA) isoforms, I and II, and acetylcholinesterase (AChE) in vitro. The results showed that the synthesized compounds were potent inhibitors of hCA I, with KIs in the low nanomolar range (66.60-278.40 nM) than the reference drug acetazolamide (AAZ), which had a KI of 439.17 nM. The hCA II was potently inhibited by compounds 5a, 5d-g and 5l, with KIs of 69.56, 39.64, 79.63, 74.76, 78.93 and 74.94 nM, respectively (AAZ, KI of 98.28 nM). Notably, compound 5a selectively inhibited hCA II with a selectivity of > 4-fold over hCA I. In terms of inhibition of AChE, the synthesized compounds had KIs ranging from 30.95 to 154.50 nM, compared to the reference drug tacrine, which had a KI of 159.61 nM. Compounds 5f, 5h and 5l were also evaluated for their ability to inhibit the MCF-7 cancer cell line proliferation and were found to have promising anticancer activity, more potent than 5-fluorouracil and cisplatin. Molecular docking studies suggested that the sulfonamide moiety of these compounds fits snugly into the active sites of hCAs and interacts with the Zn2+ ion. Furthermore, molecular dynamics simulations were performed for 200 ns to assess the stability and dynamics of each enzyme-ligand complex. The acceptability of the compounds based on Lipinski's and Jorgensen's rules was also estimated from the ADME/T results. These results indicate that the synthesized molecules have the potential to be developed into effective and safe inhibitors of hCAs and AChE and could be lead agents.Communicated by Ramaswamy H. Sarma.

Design, Synthesis, Antifungal Activity, and Molecular Docking Studies of Novel Chiral Isoxazoline-Benzofuran-Sulfonamide Derivatives

Succinate dehydrogenase (SDH) is one of the most important molecular targets for the development of novel fungicides. With the emerging problem of resistance in plant fungal pathogens, novel compounds with high fungicidal activity need to be developed, but the study of chiral pesticides for the inhibition of highly destructive plant pathogens has been rarely reported in recent years. Therefore, a series of novel chiral isoxazoline-benzofuran-sulfonamide derivatives were designed to investigate potential novel antifungal molecules. The chiral target compound 3a was cultured as a single crystal and confirmed using X-ray diffraction. All the target compounds were tested for antifungal activity, and compounds 3c, 3i, 3s, and 3r were found to have significant antifungal effects against S. sclerotiorum with EC50 values of 0.42 mg/L, 0.33 mg/L, 0.37 mg/L, and 0.40 mg/L, respectively, which were superior to the commercial fungicide fluopyram (EC50 = 0.47 mg/L). The IC50 value of compound 3i against the SDH of S. sclerotiorum was 0.63 mg/mL, which was further demonstrated by enzyme activity assays. Scanning electron microscopy showed that 3i had a significant inhibitory effect on S. sclerotiorum. In addition, the fluorescence quenching analysis assay indicated that compound 3i had a similar effect with the positive control fluopyram. Molecular docking exhibited that target compounds with chiral configuration had better affinity than racemic configuration, and 3i possessed stronger action than fluopyram, which was in keeping with the in vitro test results. These results would provide a basis and reference for the development of novel chiral fungicides.

Computational medicinal chemistry applications to target Asian-prevalent strain of hepatitis C virus

Hepatitis C Virus (HCV), affecting millions of people worldwide, is the leading cause of liver disorder, cirrhosis, and hepatocellular carcinoma. HCV is genetically diverse having eight genotypes and several subtypes predominant in different regions of the globe. The HCV NS3/4A protease is a primary therapeutic target for HCV with various FDA-approved antivirals and several clinical developments. However, available protease inhibitors (PIs) have lower potency against HCV genotype 3 (GT3), prevalent in South Asia. In this study, the incumbent computational tools were utilized to understand and explore interactions of the HCV GT3 receptor with the potential inhibitors after the virtual screening of one million compounds retrieved from the ZINC database. The molecular dynamics, pharmacological studies, and experimental studies uncovered the potential PIs as ZINC000224449889, ZINC000224374291, and ZINC000224374456 and the derivative of ZINC000224374456 from the ZINC library. The study revealed that these top-hit compounds exhibited good binding and better pharmacokinetics properties that might be considered the most promising compound against HCV GT3 protease. Viability test, on primary healthy Human Gingival Fibroblasts (HGFs) and cancerous AGS cell line, was also carried out to assess their safety profile after administration. In addition, Surface Plasmon Resonance (SPR) was also performed for the determination of affinity and kinetics of synthesized compounds with target proteins.

Novel coumarin-chalcone derivatives: Synthesis, characterization, antioxidant, cyclic voltammetry, molecular modelling and biological evaluation studies as acetylcholinesterase, α-glycosidase, and carbonic anhydrase inhibitors

In this study, a total of 12 coumarin-chalcone derivatives, 6 of which are original were synthesized. The structures of the newly synthesized compounds were elucidated by 1H NMR, 13C NMR, IR, and elemental analysis methods (7g-7l). The antioxidant potencies measured by using CUPRAC method (Trolox equivalent total antioxidant capacity) were as follows: 7j > 7i > 7c > 7d > 7k > 7l > 7f > 7h > 7e > 7g > 7a > 7b. Furthermore, the compounds were evaluated against human carbonic anhydrases I, II, acetylcholinesterase and α-glycosidase enzymes. Compounds 7c, 7e, 7g, 7i, 7j and 7l showed promising human carbonic anhydrase I inhibition compared to the standard Acetazolamide (Ki: 16.64 ± 4.72-49.82 ± 5.82 nM vs Ki: 57.64 ± 5.41 nM). In addition, all compounds exhibited strong inhibition against acetylcholinesterase and α-glycosidase. Ki values were between 2.39 ± 0.97-9.35 ± 3.95 nM (Tacrine Ki: 13.78 ± 4.36 nM) for acetylcholinesterase, and 14.49 ± 8.51-75.67 ± 26.38 nM (Acarbose Ki: 12600 ± 78.00 nM) for α-glycosidase. Binding of 7g was predicted using molecular docking and stability of the complex was confirmed with molecular dynamics simulations which shed a light on the observed activity against acetylcholinesterase. Finally, cyclic voltammetry was also used for the electrochemical characterization of the synthesized compounds.

Novel acetic acid derivatives containing quinazolin-4(3H)-one ring: Synthesis, in vitro, and in silico evaluation of potent aldose reductase inhibitors

Aldose reductase (AR) is a crucial enzyme of the polyol pathway through which glucose is metabolized under conditions of hyperglycemia related to diabetes. A series of novel acetic acid derivatives containing quinazolin-4(3H)-one ring (1-22) was synthesized and tested for in vitro AR inhibitory effect. All the target compounds exhibited nanomolar activity against the target enzyme, and all compounds displayed higher activity as compared to the reference drug epalrestat. Among them, Compound 19, named 2-(4-[(2-[(4-methylpiperazin-1-yl)methyl]-4-oxoquinazolin-3(4H)-ylimino)methyl]phenoxy)acetic acid, displayed the strongest inhibitory effect with a KI value of 61.20 ± 10.18 nM. Additionally, these compounds were investigated for activity against L929, nontumoral fibroblast cells, and MCF-7, breast cancer cells using the MTT assay. Compounds 16 and 19 showed lower toxicity against the normal L929 cells. The synthesized compounds' (1-22) absorption, distribution, metabolism, and excretion properties were also evaluated. Molecular docking simulations were used to look into the possible binding mechanisms of these inhibitors against AR.

Computer-aided drug design

Computer-Aided Drug Design tools are now an indispensable part of drug discovery that have made key contributions to the development of drugs. In this editorial, I briefly provide an overview of CADD emphasizing its potential and invite authors from academia and the pharmaceutical and biotechnology sector to present their research in this collection.

A new series of thiazole‐hydrazone hybrids for Akt‐targeted therapy of non‐small cell lung cancer

In an attempt to identify potent antitumor agents for the fight against non-small cell lung cancer, new thiazolyl hydrazones (2a-n) were synthesized and examined for their in vitro cytotoxic effects on A549 human lung adenocarcinoma and L929 mouse embryonic fibroblast cells by means of the MTT assay. Furthermore, the effects of the most potent anticancer agents on apoptosis and Akt inhibition were investigated. 2-[2-((Isoquinolin-5-yl)methylene)hydrazinyl]-4-(4-methylsulfonylphenyl)thiazole (2k) (IC₅₀  = 1.43 ± 0.12 µM) and 2-[2-((isoquinolin-5-yl)methylene)hydrazinyl]-4-(1,3-benzodioxol-5-yl)thiazole (2l) (IC₅₀  = 1.75 ± 0.07 µM) displayed more pronounced anticancer activity than cisplatin (IC₅₀  = 3.90 ± 0.10 µM) on A549 cell lines; 2-[2-((isoquinolin-5-yl)methylene)hydrazinyl]-4-(4-methoxyphenyl)thiazole (2j) (IC₅₀  = 3.93 ± 0.06 µM) showed anticancer activity close to cisplatin. These compounds were found to induce apoptosis in A549 cells. Compound 2j (IC₅₀  = 3.55 ± 0.64 µM) showed stronger Akt inhibitory activity than GSK690693 (IC₅₀  = 4.93 ± 0.06 µM), while compounds 2k and 2l did not cause Akt inhibition at IC₅₀ concentrations (1.43 and 1.75 µM, respectively). To comprehensively elucidate the binding pose of compound 2j and to provide a detailed understanding on the ligand' binding mechanism, induced-fit docking calculations were also conducted. Both in vitro and in silico studies suggest that compound 2j shows its cytotoxic and apoptotic effects on A549 cell lines via Akt inhibition. However, it is understood that compounds 2k and 2l exert their strong anticancer effects on A549 cells through different pathways.

Synthesis, Biological Evaluation and Docking Study of Mono- and Di-sulfonamide Derivatives as Antioxidant Agents and Acetylcholinesterase Inhibitors

Mono(M1-M5)- and di(DM1-DM5)-sulfonamide derivatives were synthesized by the reaction of 4-iodobenzenesulfonyl chloride compound and aniline derivatives in basic medium. The structures of the synthesized sulfonamide derivatives were characterized by spectroscopic and X-ray diffraction methods. All compounds were screened for their acetylcholinesterase (AChE) inhibitory studies and 2,2-diphenyl-1-picrylhydrazil (DPPH) radical scavenging activities. Among the compounds tested, compound M1 showed the best activity against both AChE (IC 50 = 42.09 µg/mL for AChE) and DPPH (IC 50 = 9.94 µg/mL for DPPH). Binding energies and modes were determined by placing all compounds in the active site of AChE. Molecular docking studies were performed in order to investigate binding interaction between the synthesized compounds and AChE. The most active M1 compound showed its low CDOCKER energy (-65,834 kcal/mol).

Cytotoxic effect, enzyme inhibition, and in silico studies of some novel N-substituted sulfonyl amides incorporating 1,3,4-oxadiazol structural motif

Abstract

The acetylcholinesterase and carbonic anhydrase inhibitors (AChEIs and hCAIs) remain key therapeutic agents for many bioactivities such as anti-Alzheimer and antiobesity antiepileptic, anticancer, antiinfective, antiglaucoma, and diuretic effects. Here, it has been attempted to discover novel multi-target AChEIs and hCAIs that are highly potent, orally bioavailable, may be brain penetrant, and have higher effectiveness at lower doses than tacrine and acetazolamide. After detailed investigations both in vitro and in silico, novel N-substituted sulfonyl amide derivatives (6a–j) were determined to be highly potent inhibitors for AChE and hCAs (K_Is are in the range of 23.11–52.49 nM, 18.66–59.62 nM, and 9.33–120.80 nM for AChE, hCA I, and hCA II, respectively). Moreover, according to the cytotoxic effect studies, such as the ADME-Tox, cortex neuron cells, and neuroblastoma SH-SY5Y cell line, compounds 6a, 6d, and 6h, which are the most potent representative versus the target enzymes, were identified as orally bioavailable, highly selective, and brain preferentially distributed AChEIs and hCAIs. The docking studies revealed precise binding modes between 6a, 6d, and 6h and hCA II, hCA I, and AChE, respectively. The results presented here might provide a solid basis for further investigation into more potent AChEIs and hCAIs.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11030-022-10422-8.

Virtual Screening Inhibitors of Ubiquitin-specific Protease 7 combining Pharmacophore Modeling and Molecular Docking

Ubiquitin-specific protease 7 (USP7) is one of the most extensively studied deubiquitinases. USP7 exhibits a high expression signature in various malignant tumors, suggesting that it is a marker of tumor prognosis and a potential drug target for anti-tumor therapy. In this study, virtual screening based on pharmacophore model and biological evaluation have been applied for the discovery of novel USP7 inhibitors targeting the catalytic active site. The TS-4 was screened from 215,480 small molecules and was found to have USP7 inhibitory activity. Preliminary in vitro studies disclosed its antiproliferative activity on human colon cancer cell lines (HCT-116 and RKO), compared with normal colon cell line (CCD841CoN). Molecular dynamics (MD) simulation revealed the combine mechanism between USP7 with the TS-4. The TS-4 formed stable interactions with Asp295, Phe409 and Tyr514, which were critical to enhance its biological activity. This compound will serve as a promising hit compound for facilitating the further design of novel USP7 inhibitors.

Biological effects of bis-hydrazone compounds bearing isovanillin moiety on the aldose reductase

Aldose reductase (ALR2), one of the metabolically important enzymes, catalyzes the formation of sorbitol from glucose in the polyol pathway. ALR2 inhibition is required to prevent diabetic complications. In the present study, the novel bis-hydrazone compounds bearing isovanillin moiety (GY1-12) were synthesized, and various chromatographic methods were applied to purify the ALR2 enzyme. Afterward, the inhibitory effect of the synthesized compounds on the ALR2 was screened in vitro. All the novel bis-hydrazones demonstrated activity in nanomolar levels as AR inhibitors with IC₅₀ and K_I values in the range of 12.55-35.04 nM, and 13.38-88.21 nM, respectively. Compounds GY-11, GY-7, and GY-5 against ALR2 were identified as the highly potent inhibitors, respectively, and were superior to the standard drug, epalrestat. Moreover, a comprehensive ligand-receptor interactions prediction was performed using ADME-Tox, Glide XP, and MM-GBSA modules of Schrödinger Small-Molecule Drug Discovery Suite to elucidate the novel bis-hydrazone derivatives, potential binding modes versus the ALR2. As a result, these compounds with ALR2 inhibitory effects may be potential alternative agents that can be used to treat or prevent diabetic complications.

Melanin: Production from Cheese Bacteria, Chemical Characterization, and Biological Activities

Pigments are compounds of importance to several industries, for instance, the food industry, where they can be used as additives, color intensifiers, and antioxidants. As the current trend around the world is shifting to the use of eco-friendly commodities, demand for natural dyes is increasing. Melanins are pigments that are produced by several microorganisms. Pseudomonas putida ESACB 191, isolated from goat cheese rind, was described as a brown pigment producer. This strain produces a brown pigment via the synthetic Müeller-Hinton Broth. This brown compound was extracted, purified, analyzed by FTIR and mass spectrometry, and identified as eumelanin. The maximum productivity was 1.57 mg/L/h. The bioactivity of eumelanin was evaluated as the capacity for scavenging free radicals (antioxidant activity), EC₅₀ 74.0 ± 0.2 μg/mL, and as an acetylcholinesterase inhibitor, with IC₅₀ 575 ± 4 μg/mL. This bacterial eumelanin did not show cytotoxicity towards A375, HeLa Kyoto, HepG2, or Caco2 cell lines. The effect of melanin on cholesterol absorption and drug interaction was evaluated in order to understand the interaction of melanin present in the cheese rind when ingested by consumers. However, it had no effect either on cholesterol absorption through an intestinal simulated barrier formed by the Caco2 cell line or with the drug ezetimibe.

Benzenesulfonamide derivatives as potent acetylcholinesterase, α-glycosidase, and glutathione S-transferase inhibitors: biological evaluation and molecular docking studies

Sulfonamide derivatives exhibit a wide biological activity and can function as potential medical molecules in the development of a drug. Studies have reported that the compounds have an effect on many enzymes. In this study, the derivatives of amine sulfonamide (1i-11i) were prepared with reduced imine compounds (1-11) with NaBH4 in methanol. The synthesized compounds were fully characterized by spectral data and analytical. The effect of the synthesized derivatives on acetylcholinesterase (AChE), glutathione S-transferase (GST) and α-glycosidase (α-GLY) enzymes were determined. For the AChE and α-GLY, the most powerful inhibition was observed on 10 and 10i series with KI value in the range 2.26 ± 0.45-3.57 ± 0.97 and 95.73 ± 13.67-102.45 ± 11.72 µM, respectively. KI values of the series for GST were found in the range of 22.76 ± 1.23-49.29 ± 4.49. Finally, the compounds have a stronger inhibitor in lower concentrations by the attachment of functional electronegative groups such as two halogens (-Br and -CI), -OH to the benzene ring and -SO2NH2. The crystal structures of AChE, α-GLY, and GST in complex with selected derivatives 4 and 10 show the importance of the functional moieties in the binding modes within the receptors.Communicated by Ramaswamy H. Sarma.

Pharmacoinformatics and molecular dynamics simulation studies reveal potential covalent and FDA-approved inhibitors of SARS-CoV-2 main protease 3CLpro

The SARS-CoV-2 was confirmed to cause the global pandemic of coronavirus disease 2019 (COVID-19). The 3-chymotrypsin-like protease (3CLpro), an essential enzyme for viral replication, is a valid target to combat SARS-CoV and MERS-CoV. In this work, we present a structure-based study to identify potential covalent inhibitors containing a variety of chemical warheads. The targeted Asinex Focused Covalent (AFCL) library was screened based on different reaction types and potential covalent inhibitors were identified. In addition, we screened FDA-approved protease inhibitors to find candidates to be repurposed against SARS-CoV-2 3CLpro. A number of compounds with significant covalent docking scores were identified. These compounds were able to establish a covalent bond (C-S) with the reactive thiol group of Cys145 and to form favorable interactions with residues lining the substrate-binding site. Moreover, paritaprevir and simeprevir from FDA-approved protease inhibitors were identified as potential inhibitors of SARS-CoV-2 3CLpro. The mechanism and dynamic stability of binding between the identified compounds and SARS-CoV-2 3CLpro were characterized by molecular dynamics (MD) simulations. The identified compounds are potential inhibitors worthy of further development as COVID-19 drugs. Importantly, the identified FDA-approved anti-hepatitis-C virus (HCV) drugs paritaprevir and simeprevir could be ready for clinical trials to treat infected patients and help curb COVID-19. Communicated by Ramaswamy H. Sarma.

Novel imidazo[2,1-b]thiazole-based anticancer agents as potential focal adhesion kinase inhibitors: Synthesis, in silico and in vitro evaluation

The purpose of this study was to synthesize imidazo[2,1-b]thiazole derivatives, characterize them with spectroscopical techniques and investigate for cytotoxic and apoptotic effects on glioma C6 cancer cell line. The in vitro anticancer activities were also investigated against focal adhesion kinase. Most of the compounds, particularly the derivatives carrying 3-oxo-1-tiya-4-azaspiro[4.5]decane moiety, exhibited higher or comparable activities in comparison with the reference drug, cisplatin. Compounds with methyl, propyl, phenyl moieties at the eighth and second position of the spirothiazolidinone ring showed high FAK inhibitory activities. In addition, molecular docking studies shed light on the binding modes of the synthesized compounds. The critical interactions with amino acid residues located in the active site were revealed. The results obtained from both biological assay data and computational results might provide insight into developing new inhibitors against focal adhesion kinase.

Design, synthesis, characterization, in vitro and in silico evaluation of novel imidazo[2,1-b][1,3,4]thiadiazoles as highly potent acetylcholinesterase and non-classical carbonic anhydrase inhibitors

Imidazole and thiadiazole derivatives display an extensive application in pharmaceutical chemistry, and they have been investigated as bioactive molecules for medicinal chemistry purposes. Classical carbonic anhydrase (CA) inhibitors are based on sulfonamide groups, but inhibiting all CA isoforms nonspecifically, thereby causing undesired side effects, is the main drawback of these types of inhibitors. Here we reported an investigation of novel 2,6-disubstituted imidazo[2,1-b][1,3,4]thiadiazole derivatives (9a-k, 10a, and 11a) and 2,5,6-trisubstituted imidazo[2,1-b][1,3,4]thiadiazole derivatives (12a-20a) that do not possess the zinc-binding sulfonamide group for the inhibition of human carbonic anhydrase (hCA, EC 4.2.1.1) I and II isoforms and also of acetylcholinesterase (AChE, EC 3.1.1.7). Imidazo[2,1-b][1,3,4]thiadiazoles demonstrated low nanomolar inhibitory activity against hCA I, hCA II, and AChE (K_Is are in the range of 23.44-105.50 nM, 10.32-104.70 nM, and 20.52-54.06 nM, respectively). Besides, compound 9b inhibit hCA I up to 18-fold compared to acetazolamide, while compound 10a has a 5-fold selectivity towards hCA II. The synthesized compounds were also evaluated for their cytotoxic effects on the L929 mouse fibroblast cell line. Molecular docking simulations were performed to elucidate these inhibitors' potential binding modes against hCA I and II isoforms and AChE. The novel compounds reported here can represent interesting lead compounds, and the results presented here might provide further structural guidance to discover and design more potent hCA and AChE inhibitors.

Comprehensive study on potent and selective carbonic anhydrase inhibitors: Synthesis, bioactivities and molecular modelling studies of 4-(3-(2-arylidenehydrazine-1-carbonyl)-5-(thiophen-2-yl)-1H-pyrazole-1-yl) benzenesulfonamides

In this research, rational design, synthesis, carbonic anhydrases (CAs) inhibitory effects, and cytotoxicities of the 4-(3-(2-arylidenehydrazine-1-carbonyl)-5-(thiophen-2-yl)-1H-pyrazole-1-yl)benzenesulfonamides 1-20 were reported. Compound 18 (Ki = 7.0 nM) was approximately 127 times more selective cancer-associated hCA IX inhibitor over hCA I, while compound 17 (Ki = 10.6 nM) was 47 times more selective inhibitor of hCA XI over hCA II compared to the acetazolamide. Compounds 11 (CC50 = 5.2 μM) and 20 (CC50 = 1.6 μM) showed comparative tumor-specificity (TS= > 38.5; >128.2) with doxorubicin (TS > 43.0) towards HSC-2 cancer cell line. Western blot analysis demonstrated that 11 induced slightly apoptosis whereas 20 did not induce detectable apoptosis. A preliminary analysis showed that some correlation of tumor-specificity of 1-20 with the chemical descriptors that reflect hydrophobic volume, dipole moment, lowest hydrophilic energy, and topological structure. Molecular docking simulations were applied to the synthesized ligands to elucidate the predicted binding mode and selectivity profiles towards hCA I, hCA II, and hCA IX.

Structure-Based Scaffold Repurposing toward the Discovery of Novel Cholinesterase Inhibitors

Cholinesterases (ChE) are well-known drug targets for the treatment of Alzheimer's disease (AD). In continuation of work to develop novel cholinesterase inhibitors, we utilized a structure-based scaffold repurposing approach and discovered six novel ChE inhibitors from our recently developed DNA gyrase inhibitor library. Among the identified hits, two compounds (denoted 3 and 18) were found to be the most potent inhibitor of acetylcholinesterase (AChE, IC₅₀ = 6.10 ± 1.01 μM) and butyrylcholinesterase (BuChE, IC₅₀ = 5.50 ± 0.007 μM), respectively. Compound 3 was responsible for the formation of H-bond and π-π stacking interactions within the active site of AChE. In contrast, compound 18 was well fitted in the choline-binding pocket and catalytic site of BuChE. Results obtained from in vitro cytotoxicity assays and in silico derived physicochemical and absorption, distribution, metabolism, and excretion (ADME) properties indicate that repurposed scaffold 3 and 18 could be potential drug candidates for further development as novel ChE inhibitors.

Biochemical Constituent of Ginkgo biloba (Seed) 80% Methanol Extract Inhibits Cholinesterase Enzymes in Javanese Medaka (Oryzias javanicus) Model

Background

Pathophysiological changes leading to the death of nerve cells present in the brain and spinal cord are referred to as neurodegenerative diseases. Presently, treatment of these diseases is not effective and encounters many challenges due to the cost of drug and side effects. Thus, the search for the alternative agents to replace synthetic drugs is in high demand. Therefore, the aim of this study is to evaluate the anticholinesterase properties of Ginkgo biloba seed.

Methods

The seed was extracted with 80% methanol. Toxicity studies and evaluation of anticholinesterase activities were carried out in adult Javanese medaka (Oryzias javanicus). Phytochemical study to identify the bioactive lead constituents of the crude extract was also carried out using high performance liquid chromatography (HPLC).

Results

The result shows activities with high significant differences at P < 0.001 between the treated and nontreated groups. A bioactive compound (vitaxin) was identified with the aid of HPLC method.

Conclusion

The presence of bioactive compound vitaxin is among the major secondary metabolites that contribute to increasing activities of this plant extract. High anticholinesterase activities and low toxicity effect of this plant show its benefit to be used as natural medicine or supplements.

Synthesis, evaluation, molecular docking, and molecular dynamics studies of novel N-(4-[pyridin-2-yloxy]benzyl)arylamine derivatives as potential antitubercular agents

A new series of novel triclosan (2,4,4'-trichloro-2'-hydroxydiphenylether) analogues were designed, synthesized, and screened for their in vitro antimycobacterial and antibacterial activities. Most of the compounds showed significant activity against Mycobacterium tuberculosis H37Rv strain with minimum inhibitory concentration (MIC) values in 20-40 μM range in GAST/Fe medium when compared with triclosan (43 μM) in the first week of assay, and after additional incubation, seven compounds, that is, 2a, 2c, 2g, 2h, 2i, 2j, and 2m, exhibited MIC values at the concentration of 20-40 μM. The compounds also showed more significant activity against Bacillus subtilis and Staphylococcus aureus. The synthesized compounds showed druggable properties, and the predicted ADME (absorption, distribution, metabolism, and excretion) properties were within the acceptable limits. The in silico studies predicted better interactions of compounds with target protein residues and a higher dock score in comparison with triclosan. Molecular dynamics simulation study of the most active compound 2i was performed in order to further explore the stability of the protein-ligand complex and the protein-ligand interaction in detail.

Synthesis, biological activity, molecular docking studies of a novel series of 3-Aryl-7H-thiazolo[3,2-b]-1,2,4-triazin-7-one derivatives as the acetylcholinesterase inhibitors

The acetylcholinesterase inhibitors play a critical role in the drug therapy for Alzheimer's disease. In this study, twenty-nine novel 3-aryl-7H-thiazolo[3,2-b]-1,2,4-triazin-7-one derivatives were synthesized and assayed for their human acetylcholinesterase (hAChE) inhibitory activities. Inhibitory ratio values of seventeen compounds were above 55% with 4c having the highest value as 77.19%. The compounds with the halogen atoms in the aromatic ring, and N,N-diethylamino or N,N-dimethylamino groups in the side chains at C-3 positions exhibited good inhibitory activity. SAR study was carried out by means of molecular docking technique. According to molecular docking results, the common interacting site for all compounds were found to be peripheral anionic site whereas highly active compounds were interacting with the catalytic active site too. HIGHLIGHTSA novel series of 3-aryl-7H-thiazolo[3,2-b]-1,2,4-triazin-7-one derivatives were synthesized and assayed for their human acetylcholinesterase (hAChE) inhibitory activities.The SAR study of the target 3-aryl-7H-thiazolo[3,2-b]-1,2,4-triazin-7-one derivatives was summarized.The active sites in the acetylcholinesterase were analyzed by molecular docking technique.Communicated by Ramaswamy H. Sarma.

Identification of highly active natural thyroid hormone receptor agonists by pharmacophore-based virtual screening

Thyroid hormone receptor (TR) is an important target for the treatment of metabolic diseases. The X-ray crystallographic data for the TR complexed with different ligands were employed to generate feature-based pharmacophore models of the active site of TR receptor. The derived hypothesis was then used to find novel hit compounds through an in silico virtual screening on the Universal Natural Products Database (UNPD). The binding mode and action mechanism of the hit compounds were further investigated by molecular docking and molecular dynamics studies, then compounds possessing similar binding site with the crystal ligand were subjected to binding activity assay. Finally, UNPD19665 and UNPD184785 were proved to be more active than crystal TR ligands, with a binding activity value of 9.82 nM and 12.62 nM, respectively. Communicated by Ramaswamy H. Sarma.

Molecular docking, synthesis and biological significance of pyrimidine analogues as prospective antimicrobial and antiproliferative agents

Pyrimidine nucleus is a significant pharmacophore that exhibited excellent pharmacological activities. A series of pyrimidine scaffolds was synthesized and its chemical structures were confirmed by physicochemical and spectral analysis. The synthesized compounds were evaluated for their antimicrobial potential towards Gram positive and negative bacteria as well as fungal species. They were also assessed for their anticancer activity toward a human colorectal carcinoma cell line (HCT116). Whilst results of antimicrobial potential revealed that compounds Ax2, Ax3, Ax8 and Ax14 exhibited better activity against tested microorganisms, the results of antiproliferative activity indicated that compounds Ax7 and Ax10 showed excellent activity against HCT116. Further, the molecular docking of pyrimidine derivatives Ax1, Ax9 and Ax10 with CDK8 (PDB id: 5FGK) protein indicated that moderate to better docking results within the binding pocket. Compounds Ax8 and Ax10 having significant antimicrobial and anticancer activities may be selected as lead compounds for the development of novel antimicrobial and anticancer agent, respectively.