Synthesis and in vitro carbonic anhydrases and acetylcholinesterase inhibitory activities of novel imidazolinone-based benzenesulfonamides

Synthesis and Inhibitor Effect Novel Alkoxymethyl Derivatives of Dihetero Cycloalkanes on Carbonic Anhydrase and Acetylcholinesterase

1,3-Diheterocycloalkanes derivatives are important starting materials in fine organic synthesis. These compounds can be widely used in various fields such as industry, medicine, biotechnology and chemical technology. The paper is focused on synthesis and study of alkoxymethyl derivatives of diheterocycloalkanes (M1-M15) and inhibition effect on carbonic anhydrase and acetylcholinesterase. The structures of compounds were confirmed by 1H and 13C NMR spectroscopy. Also, in this study alkoxymethyl derivatives of diheterocycloalkanes were assessed for their influence on various metabolic enzymes, including acetylcholinesterase (AChE) and human carbonic anhydrase isoenzymes (hCA I and hCA II). The results demonstrated that all these compounds exhibited potent inhibitory effects on all the target enzymes, surpassing the standard inhibitors, as evidenced by their IC50 and Ki values. The Ki values for the compounds concerning AChE, hCA I, and hCA II enzymes were in the ranges of 1.02±0.17-8.38±1.02, 15.30±3.15-58.14±5.17 and 24.05±3.70-312.94±27.24 nM, respectively.

Synthesis and biological studies of pyrimidine derivatives targeting metabolic enzymes

Novel synthesized pyrimidine derivatives were investigated against carbonic anhydrase isoenzymes I and II (hCA I and II), acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-glycosidase, and aldose reductase (AR) enzymes associated with some common diseases such as epilepsy, glaucoma, Alzheimer's disease, diabetes, and neuropathy. When the results were examined, novel synthesized pyrimidine derivatives were found to have effective inhibition abilities toward the metabolic enzymes. IC50 values and Ki values were calculated for each pyrimidine derivative and compared to positive controls. The synthesized novel pyrimidine derivatives exhibited Ki values in the range of 39.16 ± 7.70-144.62 ± 26.98 nM against hCA I, 18.21 ± 3.66-136.35 ± 21.48 nM toward hCA II, which is associated with different pathological and physiological processes, 33.15 ± 4.85-52.98 ± 19.86 nM on AChE, and 31.96 ± 8.24-69.57 ± 21.27 nM on BChE. Also, Ki values were determined in the range of 17.37 ± 1.11-253.88 ± 39.91 nM against α-glycosidase and 648.82 ± 53.74-1902.58 ± 98.90 nM toward AR enzymes. Within the scope of the study, the inhibition types of the novel synthesized pyrimidine derivatives were evaluated.

Chemistry of heterocycles as carbonic anhydrase inhibitors: A pathway to novel research in medicinal chemistry review

Nowadays, the scientific community has focused on dealing with different kinds of diseases by exploring the chemistry of various heterocycles as novel drugs. In this connection, medicinal chemists identified carbonic anhydrases (CA) as one of the biologically active targets for curing various diseases. The widespread distribution of these enzymes and the high degree of homology shared by the different isoforms offer substantial challenges to discovering potential drugs. Medicinal and synthetic organic chemists have been continuously involved in developing CA inhibitors. This review explored the chemistry of different heterocycles as CA inhibitors using the last 11 years of published research work. It provides a pathway for young researchers to further explore the chemistry of a variety of synthetic as well as natural heterocycles as CA inhibitors.

Acyl pyrazole sulfonamides as new antidiabetic agents: synthesis, glucosidase inhibition studies, and molecular docking analysis

Diabetes mellitus is a multi-systematic chronic metabolic disorder and life-threatening disease resulting from impaired glucose homeostasis. The inhibition of glucosidase, particularly α-glucosidase, could serve as an effective methodology in treating diabetes. Attributed to the catalytic function of glucosidase, the present research focuses on the synthesis of sulfonamide-based acyl pyrazoles (5a-k) followed by their in vitro and in silico screening against α-glucosidase. The envisaged structures of prepared compounds were confirmed through NMR and FTIR spectroscopy and mass spectrometry. All compounds were found to be more potent against α-glucosidase than the standard drug, acarbose (IC50 = 35.1 ± 0.14 µM), with IC50 values ranging from 1.13 to 28.27 µM. However, compound 5a displayed the highest anti-diabetic activity (IC50 = 1.13 ± 0.06 µM). Furthermore, in silico studies revealed the intermolecular interactions of most potent compounds (5a and 5b), with active site residues reflecting the importance of pyrazole and sulfonamide moieties. This interaction pattern clearly manifests various structure-activity relationships, while the docking results correspond to the IC50 values of tested compounds. Hence, recent investigation reveals the medicinal significance of sulfonamide-clubbed pyrazole derivatives as prospective therapeutic candidates for treating type 2 diabetes mellitus (T2DM).

Design, synthesis, biological evaluation and docking analysis of pyrrolidine-benzenesulfonamides as carbonic anhydrase or acetylcholinesterase inhibitors and antimicrobial agents

The synthesis and biological assessment of novel multi-functionalized pyrrolidine-containing benzenesulfonamides were reported along with their antimicrobial, antifungal, CAs inhibition, and AChE inhibition as well as DNA-binding effects. The chemical structure of the compounds was elucidated by using FTIR, NMR, and HRMS. Compound 3b, which had Ki values of 17.61 ± 3.58 nM (hCA I) and 5.14 ± 0.61 nM (hCA II), was found the be the most potent CAs inhibitor. Compounds 6a and 6b showed remarkable AChE inhibition effects with Ki values 22.34 ± 4.53 nM and 27.21 ± 3.96 nM in comparison to tacrine. Compounds 6a-6c had moderate antituberculosis effect on M. tuberculosis with a MIC value of 15.62 μg/ml. Compounds had weaker antifungal and antibacterial activity in the range of MIC 500-62.5 μg/ml against standard bacterial and fungal strains. Besides these above, molecular docking studies were performed to examine and evaluate the interaction of the remarkable compounds (3b, 6a and 6b) against the current enzymes (CAs and AChE). Novel compounds gained interest in terms of enzyme inhibitory potencies. Therefore, the most potent enzyme inhibitors may be considered lead compounds to be modified for further research.Communicated by Ramaswamy H. Sarma.

Investigation of Potential Effects of Some Indole Compounds on the Glutathione S-Transferase Enzyme

Glutathione S-transferases (GSTs) belong to the superfamily of multifunctional detoxification isoenzymes with an important role in cellular signaling. They can prevent reactive electrophilic compounds from harming the body by covalently binding identical type of moleculs to each other. GSTs can be used alone or in combination for cancer detection or diagnosis, in addition to therapeutic interventions. In recent years, indoles have become important due to their structural properties and biological activities such as antitubercular, antiulcer, anti-oxidant, and antidiabetic, as well as for the development of new anticancer agents. The current research investigated effects of some indoles with 3-carboxaldehyde structure on the GST enzyme activity. Impacts of various concentrations of indoles on the in vitro GST activity were examined. While IC50 values for the compounds ranged from 0.042 to 1.570 mM, Ki values changed between 0.018 ± 0.01 and 1.110 ± 0.15 mM. 6-Methylindole-3-carboxaldehyde (1b) exhibited the highest inhibitory effect among the indoles examined. Indole derivatives used in the study can be evaluated in further pharmacological studies due to their effects on GST activity.

Organohalogen chalcones: design, synthesis, ADMET prediction, molecular dynamics study and inhibition effect on acetylcholinesterase and carbonic anhydrase

In an effort to discover potential acetylcholinesterase (AChE) and carbonic anhydrase (CA) inhibitors, a novel series of organohalogen chalcone derivatives (12-20, 23-30) was synthesized, and their chemical structures were characterized by spectral analysis. They showed a highly potent inhibition effect on AChE and hCAs (Ki values range from 5.07 ± 0.062 to 65.53 ± 4.36 nM for AChE, 13.54 ± 2.55 to 94.11 ± 10.39 nM for hCA I, and 5.21 ± 0.54 to 57.44 ± 3.12 nM for hCA II). In addition, the chalcone derivatives with the highest inhibitor score docked into the active site of the indicated metabolic enzyme receptors, and their absorption, metabolism, and toxic properties were evaluated according to ADMET's estimation.Compounds 16 and 19 exhibited the highest inhibition score, emerged as lead compounds, and inspired the development of more potent compounds.

Melatonin and Related Compounds as Antioxidants

Oxidative stress has been reported to be involved in the onset and development of several diseases, including neurodegenerative and cardiovascular disorders, some types of cancer, and diabetes. Therefore, finding strategies to detoxify free radicals is an active area of research. One of these strategies is the use of natural or synthetic antioxidants. In this context, melatonin (MLT) has been proven to possess most of the required characteristics of an efficient antioxidant. In addition, its protection against oxidative stress continues after being metabolized, since its metabolites also exhibit antioxidant capacity. Based on the appealing properties of MLT and its metabolites, various synthetic analogues have been developed to obtain compounds with higher activity and lower side effects. This review addresses recent studies with MLT and related compounds as potential antioxidants.

The synthesis, carbonic anhydrase and acetylcholinesterase inhibition effects of sulfonyl chloride moiety containing oxazolidinones using an intramolecular aza-Michael addition

Oxazolidinones are used as various potent antibiotics, in organisms it acts as a protein synthesis inhibitor, focusing on an initial stage that encompasses the tRNA binding process. Novel intramolecular aza-Michael reactions devoid of metal catalysts have been introduced in an oxazolidone synthesis pathway, different from α,β-unsaturated ketones. Oxazolidinone derivatives were tested against acetylcholinesterase (AChE), carbonic anhydrase I and II (hCA I and hCA II) enzymes. All the synthesized compounds had potent inhibition effects with Ki values in the range of 13.57 ± 0.98 - 53.60 ± 6.81 µM against hCA I and 9.96 ± 1.02 - 46.35 ± 3.83 µM against hCA II in comparison to the acetazolamide (AZA) (Ki = 50.46 ± 6.17 µM for hCA I) and for hCA II (Ki = 41.31 ± 5.05 µM). Also, most of the compounds demonstrated potent inhibition ability towards AChE enzyme with Ki values 78.67-231.75 nM and compared to tacrine (TAC) as standard clinical inhibitor (Ki = 142.48 nM). Furthermore, ADMET analysis and molecular docking were calculated using the AChE, hCA I and hCA II enzyme proteins to correlate the data with the experimental data. In this work, recent applications of a stereoselective aza-Michael reaction as an efficient tool for of nitrogen-containing heterocyclic scaffolds and their useful to pharmacology analogs are reviewed and summarized.Communicated by Ramaswamy H. Sarma.

Acetylphenyl-substituted imidazolium salts: synthesis, characterization, in silico studies and inhibitory properties against some metabolic enzymes

Herein, we present how to synthesize thirteen new 1-(4-acetylphenyl)-3-alkylimidazolium salts by reacting 4-(1-H-imidazol-1-yl)acetophenone with a variety of benzyl halides that contain either electron-donating or electron-withdrawing groups. The structures of the new imidazolium salts were conformed using different spectroscopic methods (1H NMR, 13C NMR, 19F NMR, and FTIR) and elemental analysis techniques. Furthermore, these compounds' the carbonic anhydrase (hCAs) and acetylcholinesterase (AChE) enzyme inhibition activities were investigated. They showed a highly potent inhibition effect toward AChE and hCAs with Ki values in the range of 8.30 ± 1.71 to 120.77 ± 8.61 nM for AChE, 16.97 ± 2.04 to 84.45 ± 13.78 nM for hCA I, and 14.09 ± 2.99 to 69.33 ± 17.35 nM for hCA II, respectively. Most of the synthesized imidazolium salts appeared to be more potent than the standard inhibitor of tacrine (TAC) against AChE and Acetazolamide (AZA) against CA. In the meantime, to prospect for potential synthesized imidazolium salt inhibitor(s) against AChE and hCAs, molecular docking and an ADMET-based approach were exerted.

Benzimidazolium Salts Bearing Nitrile Moieties: Synthesis, Enzyme Inhibition Profiling, and Molecular Docking Analysis for Carbonic Anhydrase and Acetylcholinesterase

This report presents the synthesis and characterization of a range of benzimidazolium salts featuring 3-cyanopropyl groups on the 1st nitrogen atom and varied alkyl groups on the 3rd nitrogen atom within the benzimidazole structure. Benzimidazolium salts were synthesized by N-alkylation of 1-alkyl benzimidazole with 3-cyanopropyl-bromide. The new salts were characterized by 1 H and 13 C-NMR, FT-IR spectroscopic and elemental analysis techniques. In this study, the enzyme inhibition abilities of seven nitrile substituted benzimidazolium salts were investigated against acetylcholinesterase (AChE) and carbonic anhydrase isoenzymes I and II (hCA I and hCA II). They showed a highly potent inhibition effect on AChE, hCA I and hCA II (Ki values are in the range of 26.71-119.09 nM for AChE, 19.77 to 133.68 nM for hCA I and 13.09 to 266.38 nM for hCA II). Reflecting the binding mode of the synthesized cyanopropyl series, the importance of the 2,3,5,6-tetramethylbenzyl, 3-methylbenzyl and 3-benzyl groups for optimal interactions with target proteins, evaluated by molecular docking studies. At the same time, the docking findings support the inhibition constants (Ki ) values of the related compounds in this study. Potential compounds were also evaluated by their pharmacokinetic properties were predicted.

Novel bis-ureido-substituted sulfaguanidines and sulfisoxazoles as carbonic anhydrase and acetylcholinesterase inhibitors

To discover alternative substances to compounds used to treat many diseases, especially treating Alzheimer's disease (AD) and Parkinson's disease targeting carbonic anhydrase (hCA) and acetylcholinesterase (AChE) enzymes, is important. For this purpose, a series of novel bis-ureido-substituted sulfaguanidine (SG1-4) and sulfisoxazole (SO1-4) derivatives were synthesized, and their inhibitory capacities were screened against hCA isoenzymes (hCA I and II) and AChE. Possible binding mechanisms of inhibitors to the active site were elucidated by in silico studies, and the results were supported by in vitro results. Moreover, the percent radical scavenging capacities of the derivatives were also evaluated. The derivatives (SG1-4 and SO1-4) were more effective against hCAs compared to standard drug acetazolamide (KI values of 98.28-439.17 nM for hCA I and II, respectively) and exhibited the highest inhibition with the KIs in the ranges of 2.54 ± 0.50-41.02 ± 7.52 nM for hCA I, 11.20 ± 2.97-67.14 ± 13.58 nM for hCA II, and 257.60 ± 27.84-442.60 ± 52.13 nM for AChE. Also, compounds SG1 and SO1 also showed ABTS radical scavenging activity at the rate of 70% and 78%, respectively. These results will contribute to the literature for the rational design and synthesis of new potent and selective inhibitors targeting hCAs and AChE with multifunctional effects such as radical scavenging as well as inhibition. This study focused on the synthesis and inhibitory effects of bis-ureido-substituted sulfaguanidine (SG1-4) and sulfisoxazole (SO1-4) derivatives against human hCA I and II isoforms and AChE. In order to test synthesized derivatives' free radical scavenging potentials were the DPPH and ABTS assays. In silico studies elucidated possible binding mechanisms of inhibitors to the active site.

Synthesis and in vitro anticancer activity of some 2-oxindoline derivatives as potential CDK2 inhibitors

Novel series of 2-oxindoline hydrazones 6a-h, 3-hydroxy-2-oxoindolines 9a-d and 2-oxoindolin-3-ylidenes 10a-d were prepared and assessed for their anticancer activity towards breast cancer cell line (MCF7). Compounds 6c, 6d, 6g, 9d, 10a and 10b (IC50 = 14.0 ± 0.7, 15.6 ± 0.7, 13.8 ± 0.7, 4.9 ± 0.2, 6.0 ± 0.3 and 10.8 ± 0.5 µM, respectively) showed the highest growth inhibition activity against MCF7 when compared to staurosporine (IC50 = 14.5 ± 0.7 µM). Cell cycle analysis exposed arrest at G1 phase for compounds 6c, 10 and 10b, at S phase for compounds 6d and 9d, and at G1/S phase for compound 6g. Apoptotic effect of compounds 6c, 6d, 6g, 9d, 10a and 10b was confirmed via their early and late apoptotic effects. A safety profile was revealed for compounds 6c, 6d, 6g, 9d, 10a and 10b on MCF10A treated normal cell. Also, compounds 6c and 10b displayed a promising CDK2 inhibition activity (IC50 = 0.22 ± 0.01, 0.25 ± 0.01 µM, respectively). Also, docking study revealed comparable interactions with the native ligand (5-bromoindirubin). ADMET computational studies forecast the promising pharmacokinetic profile of the targeted compounds.Communicated by Ramaswamy H. Sarma.

Pyrimidines: Molecular docking and inhibition studies on carbonic anhydrase and cholinesterases

Alzheimer's disease (AD) is a neurodegenerative disorder. The disease is characterized by dementia, memory impairment, cognitive impairment, and speech impairment. Cholinesterases (ChEs; AChE, acetylcholinesterase and BChE, butyrylcholinesterase) inhibitors and their benefits of cholinergic replacement in the treatment of AD have been researched and documented by scientists in various ways to date. Recent studies prove that human carbonic anhydrases (hCAs) are also one of the important targets in the treatment of AD. Therefore, the development of new agents that can simultaneously modulate the various mechanisms or targets involved in the AD pathway may be a powerful strategy to treat AD, the current disease. Considering these data, the effects of the pyrimidines (1-7) were investigated in this study for the discovery and development of multitargeted ChEs and hCAs inhibitors associated with AD. In addition, the molecular docking analysis of the 4-amino-2-choloropyrimidine (2) was performed to understand the binding interactions on the active site of the enzyme. All compounds (1-7) showed satisfactory enzyme inhibitory potency in micromolar concentrations against AChE, BChE, hCAI, and hCAII with K_I values ranging from 0.099 to 0.241 μM, from 1.324 to 3.418 μM, from 0.201 to 0.884 μM, from 1.867 to 3.913 μM, respectively. Due to their ChEs and hCAs inhibition, these compounds (1-7) may be considered as leads for investigations in neurodegenerative diseases. All these results revealed that the 4-amino-5,6-dichloropyrimidine (7) (K_I value of 0.201 ± 0.041 μM for hCA I), the 4-amino-6-hydroxypyrimidine (4) (K_I value of 1.867 ± 0.296 μM for hCA II), the 4-amino-5,6-dichloropyrimidine (7) (K_I value of 0.099 ± 0.008 μM for AChE), and the 4-amino-2-chloropyrimidine (2) (K_I value of 1.324 ± 0.273 μM for BChE) from the pyrimidines in this series were the most promising derivatives, as they exhibited a good multifunctional inhibition at all experimental levels and in the in silico validation against these enzymes, for the treatment of AD.

Benzimidazolium Salts Containing Trifluoromethoxybenzyl: Synthesis, Characterization, Crystal Structure, Molecular Docking Studies and Enzymes Inhibitory Properties

The method for producing 4-trifluoromethoxybenzyl substituted benzimidazolium salts is described in this article. The method is based on the reaction of 4-trifluoromethoxybenzyl substituent alkylating agent with 1-alkylbenzimidazole. This method yielded 1-(4-trifluoromethoxybenzyl)-3-alkylbenzimidazolium bromide salts. These benzimidazolium salts were characterized by using ¹ H-NMR, ¹³ C-NMR, FT-IR spectroscopy, and elemental analysis techniques. The crystal structure of 1f was enlightened by single crystal X-ray diffraction studies. Also, the enzyme inhibition effects of the synthesised compounds were investigated. They demonstrated highly potent inhibition effect on acetylcholinesterase (AChE) and carbonic anhydrases (hCAs) (K_i values are in the range of 7.24±0.99 to 39.12±5.66 nM, 5.57±0.96 to 43.07±11.76 nM, and 4.38±0.43 to 18.68±3.60 nM for AChE, hCA I, and hCA II, respectively). In molecular docking study, the interactions of active compounds showing activity against AChE and hCAs enzymes were examined. The most active compound 1f has -10.90 kcal/mol binding energy value against AChE enzyme, and the potential structure compound 1e, which has activity against hCA I and hCA II enzymes, was -7.51 and -8.93 kcal/mol, respectively.

Synthesis of Novel Bromophenol with Diaryl Methanes—Determination of Their Inhibition Effects on Carbonic Anhydrase and Acetylcholinesterase

In this work, nine new bromophenol derivatives were designed and synthesized. The alkylation reactions of (2-bromo-4,5-dimethoxyphenyl)methanol (7) with substituted benzenes 8–12 produced new diaryl methanes 13–17. Targeted bromophenol derivatives 18–21 were synthesized via the O-Me demethylation of diaryl methanes with BBr3. Moreover, the synthesized bromophenol compounds were tested with some metabolic enzymes such as acetylcholinesterase (AChE), carbonic anhydrase I (CA I), and II (CA II) isoenzymes. The novel synthesized bromophenol compounds showed Ki values that ranged from 2.53 ± 0.25 to 25.67 ± 4.58 nM against hCA I, from 1.63 ± 0.11 to 15.05 ± 1.07 nM against hCA II, and from 6.54 ± 1.03 to 24.86 ± 5.30 nM against AChE. The studied compounds in this work exhibited effective hCA isoenzyme and AChE enzyme inhibition effects. The results show that they can be used for the treatment of glaucoma, epilepsy, Parkinson’s as well as Alzheimer’s disease (AD) after some imperative pharmacological studies that would reveal their drug potential.

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 K_i 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.

Isolation of Some Phenolic Compounds from Plantago subulata L. and Determination of Their Antidiabetic, Anticholinesterase, Antiepileptic and Antioxidant Activity

In the current study, some phenolic compounds, including acteoside, isoacteoside, echinacoside, and arenarioside purified and characterized from Plantago subulata. These compounds were tested for its antioxidant potential, including Fe³⁺ and Cu²⁺ reductive ability and Fe²⁺ chelating effects. The inhibitory effects of isolated phenolic compounds were tested towards human carbonic anhydrase I and II isoenzymes (hCA I and hCA II), butyrylcholinesterase (BChE) acetylcholinesterase (AChE), aldose reductase (AR) and α-glycosidase (α-gly). K_i values were found these compounds in range of 0.24±0.05-1.38±0.34 μM against hCA I, 0.194±0.018-1.03±0.06 μM against hCA II, 0.043±0.01-0.154±0.02 μM against AChE, 3.92±1.08-11.93±4.45 μM against BChE, 0.082±0.0008-1.68±0.42 μM against AR, and 6.93±2.74-17.17±6.70 μM against α-glycosidase. As a result, isolated compounds displayed inhibition effects against studied all metabolic enzymes. They are promising candidates for treating disorders like Alzheimer's disease, diabetes mellitus, glaucoma, leukemia, and epilepsy.

New Pd(II) complexes of the bisthiocarbohydrazones derived from isatin and disubstituted salicylaldehydes: Synthesis, characterization, crystal structures and inhibitory properties against some metabolic enzymes

Pd(II) complexes (Pd1, Pd2, and Pd3) were synthesized for the first time using asymmetric isatin bisthiocarbohydrazone ligands and PdCl₂(PPh₃)₂. All complexes were characterized by a range of spectroscopic and analytical techniques. The molecular structures of Pd1 and Pd3 have been determined by single-crystal X-ray diffraction analysis. The complexes are diamagnetic and exhibit square planar geometry. The asymmetric isatin bisthiocarbohydrazone ligands coordinate to Pd(II) ion in a tridentate manner, through the phenolic oxygen, imine nitrogen and thiol sulfur, forming five- and six-membered chelate rings within their structures. The fourth coordination site in these complexes is occupied by PPh₃ (triphenylphosphine). The free ligands and their Pd(II) complexes were evaluated for their carbonic anhydrase I, II (hCAs) and acetylcholinesterase (AChE) inhibitor activities. They showed a highly potent inhibition effect on AChE and hCAs. K_i values are in the range of 9 ± 0.6 - 30 ± 5.4 nM for AChE, 7 ± 0.5 - 16 ± 2.2 nM for hCA I and 3 ± 0.3-24 ± 1.9 nM for hCA II isoenzyme. The results clearly demonstrated that the ligands and their Pd(II) complexes effectively inhibited the used enzymes.

Novel metabolic enzyme inhibitors designed through the molecular hybridization of thiazole and pyrazoline scaffolds

New hybrid thiazolyl-pyrazoline derivatives (4a-k) were obtained through a facile and versatile synthetic procedure, and their inhibitory effects on the human carbonic anhydrase (hCA) isoforms I and II as well as on acetylcholinesterase (AChE) were determined. All new thiazolyl-pyrazolines showed activity at nanomolar levels as hCA I, hCA II, and AChE inhibitors, with K_I values in the range of 13.35-63.79, 7.01-115.80, and 17.89-48.05 nM, respectively. 1-[4-(4-Cyanophenyl)thiazol-2-yl]-3-(4-piperidinophenyl)-5-(4-fluorophenyl)-2-pyrazoline (4f) and 1-(4-phenylthiazol-2-yl)-3-(4-piperidinophenyl)-5-(4-fluorophenyl)-2-pyrazoline (4a) against hCAs and 1-[4-(4-chlorophenyl)thiazol-2-yl]-3-(4-piperidinophenyl)-5-(4-fluorophenyl)-2-pyrazoline (4d) and 1-[4-(4-nitrophenyl)thiazol-2-yl]-3-(4-piperidinophenyl)-5-(4-fluorophenyl)-2-pyrazoline (4b) against AChE were identified as highly potent inhibitors, superior to the standard drugs, acetazolamide and tacrine, respectively. Compounds 4a-k were also evaluated for their cytotoxic effects on the L929 mouse fibroblast (normal) cell line. Moreover, a comprehensive ligand-receptor interaction prediction was performed using the ADME-Tox, Glide XP, and MM-GBSA modules of the Schrödinger Small-Molecule Drug Discovery Suite to elucidate the potential binding modes of the new hybrid inhibitors against these metabolic enzymes.

Oleuropein and Verbascoside - Their Inhibition Effects on Carbonic Anhydrase and Molecular Docking Studies

Recently, carbonic anhydrase (CA, E.C.4.2.1.1) inhibitors from natural product have paved the way for novel drug design in the treatment and prevention of some global diseases such as glaucoma, diabetes, and cancer. For this purpose, the inhibition effects of oleuropein and verbascoside from olive (Olea europaea L.) oil on human carbonic anhydrase I, and II (hCA I, and II) isoenzymes were evaluated in the current study. The inhibition effects of both natural compounds were determined by the esterase activity (in vitro). IC₅₀ value of oleuropein and verbascoside was calculated as 1.57 and 1.73 µM for hCA I isoenzyme, respectively. At the same manner, K _i values were determined as 1.25 ± 0.42 and 2.00 ± 0.42 µM, respectively. Then, IC₅₀ value of each compound for hCA II isoenzyme was calculated as 2.23 and 1.90 µM, respectively. Similarly, K _i values were determined as 2.37 ± 0.87 µM and 1.49 ± 0.33 µM, respectively. Also, the inhibitory effects and potent binding mechanisms of oleuropein and verbascoside on hCA I, and II isoenzymes were realized by molecular docking studies. Consequently, both natural phenolic compounds demonstrated the potent inhibition profiles against the both isoenzymes. Therefore, we believe that these results may break new ground in the drug development for the treatment of some global disorders.

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.