Thiadiazole/Thiadiazine Derivatives as Insecticidal Agent: Design, Synthesis, and Biological Assessment of 1,3,4-(Thiadiazine/Thiadiazole)-Benzenesulfonamide Derivatives as IGRs Analogues against Spodoptera littoralis.

In keeping with our investigation, a simple and practical synthesis of novel heterocyclic compounds with a sulfamoyl moiety that can be employed as insecticidal agents was reported. The compound 2-hydrazinyl-N-(4-sulfamoylphenyl)-2-thioxoacetamide 1 was coupled smoothly with triethylorthoformate or a variety of halo compounds, namely phenacyl chloride, chloroacetyl chloride, chloroacetaldehyde, chloroacetone, 1,3-dichloropropane, 1,2-dichloroethane, ethyl chloroformate, 2,3-dichloro-1,4-naphthoquinone, and chloroanil respectively, which afforded the 1,3,4-thiadiazole and 1,3,4-thiadiazine derivatives. The new products structure was determined using elemental and spectral analysis. Under laboratory conditions, the biological and toxicological effects of the synthetic compounds were also evaluated as insecticides against Spodoptera littoralis (Boisd.). Compounds 3 and 5 had LC50 values of 6.42 and 6.90 mg/L, respectively. The investigated compounds (from 2 to 11) had been undergoing molecular docking investigation for prediction of the optimal arrangement and strength of binding between the ligand (herein, the investigated compounds (from 2 to 11)) and a receptor (herein, the 2CH5) molecule. The binding affinity within docking score (S, kcal/mol) ranged between -8.23 (for compound 5), -8.12 (for compound 3) and -8.03 (for compound 9) to -6.01 (for compound 8). These compounds were shown to have a variety of binding interactions within the 2CH5 active site, as evidenced by protein-ligand docking configurations. This study gives evidence that those compounds have 2CH5-inhibitory capabilities and hence may be used for 2CH5-targeting development. Furthermore, the three top-ranked compounds (5, 3, and 9) and the standard buprofezin were subjected to density functional theory (DFT) analysis. The highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy difference (ΔE) of compounds 5, 3, and 9 was found to be comparable to that of buprofezin. These findings highlighted the potential and relevance of charge transfer at the molecular level.

Probing benzenesulfonamide-thiazolidinone hybrids as multitarget directed ligands for efficient control of type 2 diabetes mellitus through targeting the enzymes: α-glucosidase and carbonic anhydrase II.

Diabetes mellitus is a chronic metabolic disorder characterized by improper expression/function of a number of key enzymes that can be regarded as targets for anti-diabetic drug design. Herein, we report the design, synthesis, and biological assessment of two series of thiazolidinone-based sulfonamides 4a-l and 5a-c as multitarget directed ligands (MTDLs) with potential anti-diabetic activity through targeting the enzymes: α-glucosidase and human carbonic anhydrase (hCA) II. The synthesized sulfonamides were evaluated for their inhibitory activity against α-glucosidase where most of the compounds showed good to potent activities. Compounds 4d and 4e showed potent inhibitory activities (IC50 = 0.440 and 0.3456 µM), comparable with that of the positive control (acarbose; IC50 = 0.420 µM). All the synthesized derivatives were also tested for their inhibitory activities against hCA I, II, IX, and XII. They exhibited different levels of inhibition against these isoforms. Compound 4d outstood as the most potent one against hCA II with Ki equals to 7.0 nM, more potent than the reference standard (acetazolamide; Ki = 12.0 nM). In silico studies for the most active compounds within the active sites of α-glucosidase and hCA II revealed good binding modes that can explain their biological activities. MM-GBSA refinements and molecular dynamic simulations were performed on the top-ranking docking pose of the most potent compound 4d to confirm the formation of stable complex with both targets. Compound 4d was screened for its in vivo antihyperglycemic efficacy by using the oral glucose tolerance test. Compound 4d decreased blood glucose level to 217 mg/dl, better than the standard acarbose (234 mg/dl). Hence, this revealed its synergistic mode of action on post prandial hyperglycemia and hepatic gluconeogenesis. Thus, these benzenesulfonamide thiazolidinone hybrids could be considered as promising multi-target candidates for the treatment of type II diabetes mellitus.

Identification, crystallization, and first X-ray structure analyses of phenyl boronic acid-based inhibitors of human carbonic anhydrase-II.

Human carbonic anhydrases (hCAs) play a central role in various physiological processes in the human body. HCAs catalyze the reversible hydration of CO2 into HCO3-, and hence maintains the fluid and pH balance. Overexpression of CA II is associated with diseases, such as glaucoma, and epilepsy. Therefore, CAs are important clinical targets and inhibition of different isoforms, especially hCA II is used in treatment of glaucoma, altitude sickness, and epilepsy. Therapeutically used CA inhibitors (CAI) are sulfonamide-based, such as acetazolamide, dichlorphenamide, methazolamide, ethoxzolamide, etc. However, they exhibit several undesirable effects such as numbness, tingling of extremities, malaise, metallic taste, fatigue, renal calculi, and metabolic acidosis. Therefore, there is an urgent need to identify safe and effective inhibitors of the hCAs. In this study, different phenyl boronic acids 1-5 were evaluated against bovine (bCA II) and hCA II. Among all, compound 1 (4-acetylphenyl boronic acid) was found to be active against bCAII and hCA II with IC50 values of 246 ± 0.48 and 281.40 ± 2.8 µM, respectively, while the remaining compounds were found in-active. Compound 1 was identified as competitive inhibitor of hCA II enzyme (Ki = 283.7 ± 0.002 µM). Additionally, compound 1 was found to be non-toxic against BJ Human fibroblast cell line. The X-ray crystal structure for hCA II in-complex with compound 1 was evaluated to a resolution of 2.6 Å. In fact, this the first structural analysis of a phenyl boron-based inhibitor bound to hCA II, allowing an additional structure-activity analysis of the compounds. Compound 1 was found to be directly bound in the active site of hCA II by interacting with His94, His119, and Thr199 residues. In addition, a bond of 3.11 Å between the zinc ion and coordinated boron atom of the boronic acid moiety of compound 1 was also observed, contributing to binding affinity of compound 1 for hCA II. PDB ID: 8IGF.

Explainable artificial intelligence in the design of selective carbonic anhydrase I-II inhibitors via molecular fingerprinting.

Inhibiting the enzymes carbonic anhydrase I (CA I) and carbonic anhydrase II (CA II) presents a potential avenue for addressing nervous system ailments such as glaucoma and Alzheimer's disease. Our study explored harnessing explainable artificial intelligence (XAI) to unveil the molecular traits inherent in CA I and CA II inhibitors. The PubChem molecular fingerprints of these inhibitors, sourced from the ChEMBL database, were subjected to detailed XAI analysis. The study encompassed training 10 regression models using IC50 values, and their efficacy was gauged using metrics including R2, RMSE, and time taken. The Decision Tree Regressor algorithm emerged as the optimal performer (R2: 0.93, RMSE: 0.43, time-taken: 0.07). Furthermore, the PFI method unveiled key molecular features for CA I inhibitors, notably PubChemFP432 (C(O)N) and PubChemFP6978 (C(O)O). The SHAP analysis highlighted the significance of attributes like PubChemFP539 (C(O)NCC), PubChemFP601 (C(O)OCC), and PubChemFP432 (C(O)N) in CA I inhibitiotable n. Likewise, features for CA II inhibitors encompassed PubChemFP528(C(O)OCCN), PubChemFP791 (C(O)OCCC), PubChemFP696 (C(O)OCCCC), PubChemFP335 (C(O)NCCN), PubChemFP580 (C(O)NCCCN), and PubChemFP180 (C(O)NCCC), identified through SHAP analysis. The sulfonamide group (S), aromatic ring (A), and hydrogen bonding group (H) exert a substantial impact on CA I and CA II enzyme activities and IC50 values through the XAI approach. These insights into the CA I and CA II inhibitors are poised to guide future drug discovery efforts, serving as a beacon for innovative therapeutic interventions.

2-((1H-Benzo[d]imidazol-2-yl)amino)benzo[d]thiazole-6-sulphonamides: a class of carbonic anhydrase II and VII-selective inhibitors.

A small library of substituted cyclic guanidine incorporated benzothiazole-6-sulphonamides was synthesized. All obtained compounds were investigated for their inhibitory activity against the key brain-associated human carbonic anhydrase isoform hCA VII (a promising target for the treatment of neuropathic pain) and three isoforms expressed in brain and other tissues, hCA I, II, and IV. Sulphaguanidine derivatives 9a-d were inactive on the all investigated isoforms while the primary sulphonamide containing guanidines 6a-c and 7a-c were inactive towards hCA IV but displayed inhibiting properties on hCA I, II, and VII with KIs values in the low nanomolar to micromolar ranges. The results indicated that isoforms hCA II and VII were potently and selectively inhibited by these compounds, whereas the cytosolic hCA I was less sensitive to inhibition. The derivatives reported in this study might be useful for design of more potent and selective inhibitors of hCA II and VII.

In the footsteps of an inhibitor unbinding from the active site of human carbonic anhydrase II.

The crystal structure of human carbonic anhydrase (HCA) II bound to an inhibitor molecule, 6-hydroxy-2-thioxocoumarin (FC5), shows FC5 to be located in a hydrophobic pocket at the active site. The present work employs classical molecular dynamics (MD) simulation to follow the FC5 molecule for 1 µs as it unbinds from its binding location, adopts the path of substrate/product diffusion (path 1) to leave the active site at around 75 ns. It is then found to undergo repeated binding and unbinding at different locations on the surface of the enzyme in water. Several transient excursions through different regions of the enzyme are also observed prior to its exit from the active site. These transient paths are combined with functionally relevant cavities/channels to enlist five additional pathways (path 2-6). Pathways 1-6 are subsequently explored using steered MD and umbrella sampling simulations. A free energy barrier of 0.969 kcal mol-1 is encountered along path 1, while barriers in the range of 0.57-2.84 kcal mol-1 are obtained along paths 2, 4 and 5. We also analyze in detail the interaction between FC5 and the enzyme along each path as the former leaves the active site of HCA II. Our results indicate path 1 to be the major exit pathway for FC5, although competing contributions may also come from the paths 2, 4 and 5.Communicated by Ramaswamy H. Sarma.

A Series of Thiadiazolyl-Benzenesulfonamides Incorporating an Aromatic Tail as Isoform-Selective, Potent Carbonic Anhydrase II/XII Inhibitors.

We describe the synthesis of a series of thiadiazolyl-benzenesulfonamide derivatives carrying an aromatic tail linked by an amide linker (12-34), as human carbonic anhydrase (hCA) inhibitors. These thiadiazol derivatives were evaluated against four physiologically relevant CA isoforms (hCA I, II, IX, and XII), and demonstrated intriguing inhibitory activity against CA II with Ki values in the range of 2.4-31.6 nM. Besides hCA II, also hCA XII activity was potently inhibited by some of the derivatives (Ki =1.5-88.5 nM), producing dual inhibitors of both isoforms. Notably, compound 17 was the most potent dual CA II (Ki =3.1 nM) and XII (Ki =1.5 nM) inhibitor with a significant selectivity ratio over CA I and IX isoforms. In conclusion, although all compounds exhibited preferential activity towards hCA II, the nature of the substituents at the tail part of the main scaffold influenced the activity and selectivity toward other isoforms.

Design, Synthesis and Molecular Docking Study of Novel 3-Phenyl-ß-Alanine-Based Oxadiazole Analogues as Potent Carbonic Anhydrase II Inhibitors.

Carbonic anhydrase-II (CA-II) is strongly related with gastric, glaucoma, tumors, malignant brain, renal and pancreatic carcinomas and is mainly involved in the regulation of the bicarbonate concentration in the eyes. With an aim to develop novel heterocyclic hybrids as potent enzyme inhibitors, we synthesized a series of twelve novel 3-phenyl-ß-alanine 1,3,4-oxadiazole hybrids (4a-l), characterized by 1H- and 13C-NMR with the support of HRESIMS, and evaluated for their inhibitory activity against CA-II. The CA-II inhibition results clearly indicated that the 3-phenyl-ß-alanine 1,3,4-oxadiazole derivatives 4a-l exhibited selective inhibition against CA-II. All the compounds (except 4d) exhibited good to moderate CA-II inhibitory activities with IC50 value in range of 12.1 to 53.6 µM. Among all the compounds, 4a (12.1 ± 0.86 µM), 4c (13.8 ± 0.64 µM), 4b (19.1 ± 0.88 µM) and 4h (20.7 ± 1.13 µM) are the most active hybrids against carbonic CA-II. Moreover, molecular docking was performed to understand the putative binding mode of the active compounds. The docking results indicates that these compounds block the biological activity of CA-II by nicely fitting at the entrance of the active site of CA-II. These compounds specifically mediating hydrogen bonding with Thr199, Thr200, Gln92 of CA-II.

Metal Ion Binding Induces Local Protein Unfolding and Destabilizes Human Carbonic Anhydrase II.

Human carbonic anhydrase II (HCA) is a robust metalloprotein and an excellent biological model system to study the thermodynamics of metal ion coordination. Apo-HCA binds one zinc ion or two copper ions. We studied these binding processes at five temperatures (15-35 °C) using isothermal titration calorimetry, yielding thermodynamic parameters corrected for pH and buffer effects. We then sought to identify binding-induced structural changes. Our data suggest that binding at the active site organizes 6-8 residues; however, copper binding near the N-terminus results in a net unfolding of 6-7 residues. This surprising destabilization was confirmed using circular dichroism and protein stability measurements. Metal binding induced unfolding may represent an important regulatory mechanism, but it may be easily missed by NMR and X-ray crystallography. Thus, in addition to highlighting a highly novel binding-induced unfolding event, we demonstrate the value of calorimetry for studying the structural implications of metal binding.

Commikuanoids A-C: New cycloartane triterpenoids with exploration of carbonic anhydrase-II inhibition from the resins of Commiphora kua by in vitro and in silico molecular docking.

Three new cycloartane triterpenoids, commikuanoids A-C (1-3), together with four known compounds 4-7, were isolated from the resin of Commiphora kua. Their structures were confirmed by advanced NMR techniques such as 1D (1H and 13C) and 2D (HMBC, HSQC, COSY, NOESY and NOE) and high-resolution mass spectrometry (HRMS). Five compounds (1-5) were screened for in vitro carbonic anhydrase II (CA II) inhibitory activity. All the tested compounds demonstrated significant activity against CA II with IC50 values ranging from 4.9-19.6 µM. Moreover, the binding pattern of each compound in the binding site of CA-II was predicted through in silico molecular docking approach. It was observed that compounds 2, 4, and 5 binds with the Zn ion present in the active site of CA II, while compounds 1 and 3 mediated hydrogen bonding with Thr199 of CA-II, and all the compounds showed good binding score (> - 5 kcal/mol).

One-Pot Procedure for the Synthesis of Asymmetric Substituted Ureido Benzene Sulfonamides as Effective Inhibitors of Carbonic Anhydrase Enzymes.

We report a one-pot procedure for the synthesis of asymmetrical ureido-containing benzenesulfonamides based on in situ generation of the corresponding isocyanatobenezenesulfonamide species, which were trapped with the appropriate amines. A library of new compounds was generated and evaluated in vitro for their inhibition properties against a representative panel of the human (h) metalloenzymes carbonic anhydrases (EC 4.2.1.1), and the best performing compounds on the isozyme II (i.e., 7c, 9c, 11g, and 12c) were screened for their ability to reduce the intraocular pressure in glaucomatous rabbits. In addition, the binding modes of 7c, 11f, and 11g were assessed by means of X-ray crystallography.

Discovery of sulfadrug-pyrrole conjugates as carbonic anhydrase and acetylcholinesterase inhibitors.

Human carbonic anhydrase (hCA) isoenzymes are zinc ion-containing, widespread metalloenzymes and they classically play a role in pH homeostasis maintenance. CA inhibitors suppress the CA activity and their usage has been clinically established as antiglaucoma agents, antiepileptics, diuretics, and in some other disorders. Alzheimer's disease (AD) is a slowly progressive neurodegenerative disorder and a fatal disease of the brain. An advanced method to cure AD includes the strategy to design acetylcholinesterase (AChE) inhibitors. A novel series of pyrrole-3-one derivatives containing sulfa drugs (5a-i) were determined to be highly potent inhibitors for AChE and hCA I and hCA II (inhibitory constant [Ki ] values are in the range of 6.50 ± 1.02-37.46 ± 4.12 nM, 1.20 ± 0.19-44.21 ± 1.09 nM, and 8.93 ± 1.58-46.86 ± 8.41 nM for AChE, hCA I, and hCA II, respectively). The designed compounds often show a more effective inhibition than the chemicals used as the standard. Among these compounds, 5f was the most effective compound against hCA I, and compound 5e was the most effective compound against hCA II. It was determined that compound 5c was the most effective inhibitor for AChE.

Synthesis and some enzyme inhibition effects of isoxazoline and pyrazoline derivatives including benzonorbornene unit.

Four new and four known isoxazoline derivatives were synthesized from the reactions of benzonorbornadiene with nitrile oxides formed from the corresponding benzaldehydes. Three new and one known pyrazoline derivatives were also synthesized from the reactions of the benzonorbornadiene with nitrile imines formed from the corresponding compounds. The synthesized nitrogen-based novel heterocyclic compounds were evaluated against the human carbonic anhydrase isoenzymes I and II (hCA I and hCA II), acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) enzymes. The synthesized nitrogen-based novel heterocyclic compounds showed IC50 values in the range of 2.69-7.01 against hCA I, 2.40-4.59 against hCA II, 0.81-1.32 µM against AChE, and 20.83-1.70 µM against BChE enzymes. On the contrary, nitrogen-based novel heterocyclic compounds demonstrated Ki values between 2.93 ± 0.59-8.61 ± 1.39 against hCA I, 2.05 ± 0.62-4.97 ± 0.95 against hCA II, 0.34 ± 0.02-0.92 ± 0.17 nM against AChE, and 0.50 ± 0.04-1.20 ± 0.16 µM against BChE enzymes. The synthesized nitrogen-based novel heterocyclic compounds exhibited effective inhibition profiles against both indicated metabolic enzymes. These results may contribute to the development of new drugs particularly to treat some disorders, which are widespread in the world including glaucoma and Alzheimer's diseases.

New Carbonic Anhydrase-II Inhibitors from Marine Macro Brown Alga Dictyopteris hoytii Supported by In Silico Studies.

In continuation of phytochemical investigations of the methanolic extract of Dictyopteris hoytii, we have obtained twelve compounds (1-12) through column chromatography. Herein, three compounds, namely, dimethyl 2-bromoterepthalate (3), dimethyl 2,6-dibromoterepthalate (4), and (E)-3-(4-(dimethoxymethyl)phenyl) acrylic acid (5) are isolated for the first time as a natural product, while the rest of the compounds (1, 2, 6-12) are known and isolated for the first time from this source. The structures of the isolated compounds were elucidated by advanced spectroscopic 1D and 2D NMR techniques including 1H, 13C, DEPT, HSQC, HMBC, COSY, NEOSY, and HR-MS and comparison with the reported literature. Furthermore, eight compounds (13-20) previously isolated by our group from the same source along with the currently isolated compounds (1-12) were screened against the CA-II enzyme. All compounds, except 6, 8, 14, and 17, were evaluated for in vitro bovine carbonic anhydrase-II (CA-II) inhibitory activity. Eventually, eleven compounds (1, 4, 5, 7, 9, 10, 12, 13, 15, 18, and 19) exhibited significant inhibitory activity against CA-II with IC50 values ranging from 13.4 to 71.6 µM. Additionally, the active molecules were subjected to molecular docking studies to predict the binding behavior of those compounds. It was observed that the compounds exhibit the inhibitory potential by specifically interacting with the ZN ion present in the active site of CA-II. In addition to ZN ion, two residues (His94 and Thr199) play an important role in binding with the compounds that possess a carboxylate group in their structure.

Discovery of novel aminosaccharide-based sulfonamide derivatives as potential carbonic anhydrase II inhibitors.

In this paper, a new class of novel sulfonamides incorporating aminosaccharide tails were designed and synthesized based on the sugar-tail approach. Then, all the novel compounds were evaluated for their inhibitory activities against three carbonic anhydrase (CA, EC 4.2.1.1) isoenzymes (hCA I, hCA II and hCA IX). Interestingly, effective inhibition of these three CA isoforms were observed, especially the glaucoma associated isoform hCA II. It is worth noting that these glycoconjugated sulfonamide derivatives also showed better CA inhibitory effects compared to the initial segment carzenide. Among them, compound 8d was the most effective inhibitor with IC50 of 60 nM against hCA II. Subsequent physicochemical properties studies showed that all compounds have good water solubility and neutral pH values in solutions. And these important physicochemical properties make target compounds acquire obvious advantages in the preparation of topical and nonirritating antiglaucoma drugs. Moreover, the target compounds showed lower corneal cytotoxicity than acetazolamide (AAZ) and good metabolic stability in vitro. In addition, molecular docking studies confirmed the interactions between aminosaccharide fragment and hydrophilic subpocket of hCA II active site were crucial for the enhanced CA inhibitory activity. Taken together, these results suggested 8d would be a promising lead compound for the development of topical antiglaucoma CAIs.

Synthesis and Inhibition Activity Study of Triazinyl-Substituted Amino(alkyl)-benzenesulfonamide Conjugates with Polar and Hydrophobic Amino Acids as Inhibitors of Human Carbonic Anhydrases I, II, IV, IX, and XII.

Primary sulfonamide derivatives with various heterocycles represent the most widespread group of potential human carbonic anhydrase (hCA) inhibitors with high affinity and selectivity towards specific isozymes from the hCA family. In this work, new 4-aminomethyl- and aminoethyl-benzenesulfonamide derivatives with 1,3,5-triazine disubstituted with a pair of identical amino acids, possessing a polar (Ser, Thr, Asn, Gln) and non-polar (Ala, Tyr, Trp) side chain, have been synthesized. The optimized synthetic, purification, and isolation procedures provided several pronounced benefits such as a short reaction time (in sodium bicarbonate aqueous medium), satisfactory yields for the majority of new products (20.6-91.8%, average 60.4%), an effective, well defined semi-preparative RP-C18 liquid chromatography (LC) isolation of desired products with a high purity (>97%), as well as preservation of green chemistry principles. These newly synthesized conjugates, plus their 4-aminobenzenesulfonamide analogues prepared previously, have been investigated in in vitro inhibition studies towards hCA I, II, IV and tumor-associated isozymes IX and XII. The experimental results revealed the strongest inhibition of hCA XII with low nanomolar inhibitory constants (Kis) for the derivatives with amino acids possessing non-polar side chains (7.5-9.6 nM). Various derivatives were also promising for some other isozymes.

Determination of intracellular protein-ligand binding affinity by competition binding in-cell NMR.

Structure-based drug development suffers from high attrition rates due to the poor activity of lead compounds in cellular and animal models caused by low cell penetrance, off-target binding or changes in the conformation of the target protein in the cellular environment. The latter two effects cause a change in the apparent binding affinity of the compound, which is indirectly assessed by cellular activity assays. To date, direct measurement of the intracellular binding affinity remains a challenging task. In this work, in-cell NMR spectroscopy was applied to measure intracellular dissociation constants in the nanomolar range by means of protein-observed competition binding experiments. Competition binding curves relative to a reference compound could be retrieved either from a series of independent cell samples or from a single real-time NMR bioreactor run. The method was validated using a set of sulfonamide-based inhibitors of human carbonic anhydrase II with known activity in the subnanomolar to submicromolar range. The intracellular affinities were similar to those obtained in vitro, indicating that these compounds selectively bind to the intracellular target. In principle, the approach can be applied to any soluble intracellular target that gives rise to measurable chemical shift changes upon ligand binding.

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 KI 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.

Inhibition Profiles of Some Symmetric Sulfamides Derived from Phenethylamines on Human Carbonic Anhydrase I, and II Isoenzymes.

In this work, the inhibitory effect of some symmetric sulfamides derived from phenethylamines were determined against human carbonic anhydrase (hCA) I, and II isoenzymes, and compared with standard compound acetazolamide. IC50 values were obtained from the Enzyme activity (%)-[Symmetric sulfamides] graphs. Also, Ki values were calculated from the Lineweaver-Burk graphs. Some symmetric sulfamides compounds (11-18) demonstrated excellent inhibition effects against hCA I, and II isoenzymes. These compounds demonstrated effective inhibitory profiles with IC50 values in ranging from 21.66-28.88 nM against hCA I, 14.44-30.13 nM against hCA II. Among these compounds, the best Ki value for hCA I (Ki : 8.34±1.60 nM) and hCA II (Ki : 16.40±1.00 nM) is compound number 11. Besides, the IC50 value of acetazolamide used as a standard was determined as hCA I, hCA II 57.75 nM, 49.50 nM, respectively. Moreover, in silico ADME-Tox study showed that all synthesized compounds (11-18) had good oral bioavailability in light of Jorgensen's rule of three, and of Lipinski's rule of five.

Spectrally Resolved Estimation of Water Entropy in the Active Site of Human Carbonic Anhydrase II.

A major challenge in understanding ligand binding to biomacromolecules lies in dissecting the underlying thermodynamic driving forces at the atomic level. Quantifying the contributions of water molecules is often especially demanding, although they can play important roles in biomolecular recognition and binding processes. One example is human carbonic anhydrase II, whose active site harbors a conserved network of structural water molecules that are essential for enzymatic catalysis. Inhibitor binding disrupts this water network and changes the hydrogen-bonding patterns in the active site. Here, we use atomistic molecular dynamics simulations to compute the absolute entropy of the individual water molecules confined in the active site of hCAII using a spectrally resolved estimation (SRE) approach. The entropy decrease of water molecules that remain in the active site upon binding of a dorzolamide inhibitor is caused by changes in hydrogen bonding and stiffening of the hydrogen-bonding network. Overall, this entropy decrease is overcompensated by the gain due to the release of three water molecules from the active site upon inhibitor binding. The spectral density calculations enable the assignment of the changes to certain vibrational modes. In addition, the range of applicability of the SRE approximation is systematically explored by exploiting the gradually changing degree of immobilization of water molecules as a function of the distance to a phospholipid bilayer surface, which defines an "entropy ruler". These results demonstrate the applicability of SRE to biomolecular solvation, and we expect it to become a useful method for entropy calculations in biomolecular systems.