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.

An asiatic acid derived trisulfamate acts as a nanomolar inhibitor of human carbonic anhydrase VA

This investigation delves into the inhibitory capabilities of a specific set of triterpenoic acids on diverse isoforms of human carbonic anhydrase (hCA). Oleanolic acid (1), maslinic acid (2), betulinic acid (3), platanic acid (4), and asiatic acid (5) were chosen as representative triterpenoids for evaluation. The synthesis involved acetylation of parent triterpenoic acids 1-5, followed by sequential reactions with oxalyl chloride and benzylamine, de-acetylation of the amides, and subsequent treatment with sodium hydride and sulfamoyl chloride, leading to the formation of final compounds 21-25. Inhibition assays against hCAs I, II, VA, and IX demonstrated noteworthy outcomes. A derivative of betulinic acid, compound 23, exhibited a Ki value of 88.1 nM for hCA VA, and a derivative of asiatic acid, compound 25, displayed an even lower Ki value of 36.2 nM for the same isoform. Notably, the latter compound displayed enhanced inhibitory activity against hCA VA when compared to the benchmark compound acetazolamide (AAZ), which had a Ki value of 63.0 nM. Thus, this compound surpasses the inhibitory potency and isoform selectivity of the standard compound acetazolamide (AAZ). In conclusion, the research offers insights into the inhibitory potential of selected triterpenoic acids across diverse hCA isoforms, emphasizing the pivotal role of structural attributes in determining isoform-specific inhibitory activity. The identification of compound 25 as a robust and selective hCA VA inhibitor prompts further exploration of its therapeutic applications.

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.

Sulfonyl thiourea derivatives from 2-aminodiarylpyrimidines: In vitro and in silico evaluation as potential carbonic anhydrase I, II, IX, and XII inhibitors

A series of synthesized sulfonyl thiourea derivatives (7a-o) of substituted 2-amino-4,6-diarylpyrimidines (4a-o) exhibited the remarkable inhibitory activity against some the human carbonic anhydrases (hCAs), including hCA I, II, IX, and XII isoforms. The inhibitory efficacy of synthesized sulfonyl thiourea derivatives were experimentally validated by in vitro enzymatic assays. 7a (KI  = 46.14 nM), 7j (KI  = 48.92 nM), and 7m (KI  = 62.59 nM) (for isoform hCA I); 7f (KI  = 42.72 nM), 7i (KI  = 40.98 nM), and 7j (KI  = 33.40 nM) (for isoform hCA II); 7j (KI  = 228.5 nM), 7m (KI  = 195.4 nM), and 7n (KI  = 210.1 nM) (for isoform hCA IX); 7l (KI  = 116.9 nM), 7m (KI  = 118.8 nM), and 7n (KI  = 147.2 nM) (for isoform hCA XII) in comparison with KI values of 452.1, 327.3, 437.2, and 338.9 nM, respectively, of the standard drug AAZ. These compounds also had significantly more potent inhibitory action against cytosolic isoform hCA I and tumor-associated isoforms hCA IX and hCA XII. Furthermore, the potential inhibitory compounds were subjected to in silico screening for molecular docking and molecular dynamics simulations. The results of in vitro and in silico studies revealed that compounds 7a, 7j, and 7m were the most promising derivatives in this series due to their significant effects on studied hCA I, II, IX, and XII isoforms, respectively. The results showed that the sulfonyl thiourea moiety was accommodated deeply in the active site and interacted with the zinc ion in the receptors.

Sulfonamide derivatives with benzothiazole scaffold: Synthesis and carbonic anhydrase I-II inhibition properties

The secondary sulfonamide derivatives containing benzothiazole scaffold (1-10) were synthesized to determine their inhibition properties on two physiologically essential human carbonic anhydrases isoforms (hCAs, EC, 4.2.1.1), hCA I, and hCA II. The inhibitory effects of the compounds on hCA I and hCA II isoenzymes were investigated by comparing their IC50 and Ki values. The Ki values of compounds (1-10) against hCA I and hCA II are in the range of 0.052 ± 0.022-0.971 ± 0.280 and 0.025 ± 0.010-0.682 ± 0.335, respectively. Some of these inhibited the enzyme more effectively than the standard drug, acetazolamide. In particular, compounds 5 and 4 were found to be most effective on hCA I and hCA II.

Design, synthesis, and molecular docking studies of benzimidazole-1,3,4-triazole hybrids as carbonic anhydrase I and II inhibitors

In this study, with an aim to develop novel heterocyclic hybrids as potent enzyme inhibitors, we synthesized a series of 10 novel 2-(4-(4-ethyl-5-(2-(substitutedphenyl)-2-oxo-ethylthio)-4H-1,2,4-triazol-3-yl)-phenyl)-5,6-dimethyl-1H-benzimidazole (5a-5j) derivatives and characterized by 1 H-NMR, 13 C-NMR, and HRMS. These compounds were evaluated for their inhibitory activity against hCA I and hCA II. All the compounds exhibited good hCA I and hCA II inhibitory activities with IC50 values in range of 1.288 μM-3.122 μM. Among all these compounds, compound 5e, with an IC50 value of 1.288 μM is the most active against carbonic hCA I. Compound 5h with an IC50 value of 1.532 μM is the most active against carbonic hCA-II. Compounds 5a-5j were also evaluated for their cytotoxic effects on the L929 mouse fibroblast (normal) cell line. The compounds were also analyzed for their antioxidant capacity by TAS, FRAP, and DPPH activity. Enzyme inhibition kinetics showed all compounds 5a-5j to inhibit the enzyme by non-competitive. The most active compound 5e for hCA I and compound 5h for hCA-II were subjected to molecular docking, which revealed their binding interactions with the enzyme's active site, confirming the experimental findings.

Synthesis, characterization and docking studies of benzenesulfonamide derivatives containing 1,2,3-triazole as potential ınhibitor of carbonic anhydrase I-II enzymes

Carbonic Anhydrases (CAs) are an important family of metalloenzymes that contain zinc (Zn2+) ions in their active site and catalyze the conversion of carbon dioxide to bicarbonate and proton and found in all living organisms. Sulfonamides are well-known inhibitors of CAs isoenzymes. In this study, a series of benzenesulfonamide derivatives (9a-h) containing 1,2,3-triazole-moiety were designed, synthesized and their structures were characterized by spectroscopic methods. In addition, molecular structures of compounds 5a, 5 b, 9e and 9f were elucidated by X-ray diffraction technique. To investigate drug similarity of 9a-h compounds, Lipinski's five rules (ADMET: absorption, distribution, metabolism, excretion and toxicity) were carried out by in silico studies. According to results, the compounds showed drug-like properties. Docking studies were applied to determine the scores, interactions and binding modes of compounds 9a-h against hCA I and hCA II enzymes. Compound 9c (-5.13 kcal/mol docking score) against hCA I enzyme and 9 h (-5.32 kcal/mol docking score) against hCA II enzyme showed potent inhibitory properties. The binding interactions of the compounds with the carbonic anhydrases were examined by docking studies.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.

Design, synthesis, and biological investigation of selective human carbonic anhydrase II, IX, and XII inhibitors using 7-aryl/heteroaryl triazolopyrimidines bearing a sulfanilamide scaffold

A novel library of human carbonic anhydrase (hCA) inhibitors based on the 2-sulfanilamido[1,2,4]triazolo[1,5-a]pyrimidine skeleton modified at its 7-position was prepared by an efficient convergent procedure. These derivatives were evaluated in vitro for their inhibition properties against a representative panel of hCA isoforms (hCA I, II, IV, IX, and XII). The target tumour-associated isoforms hCA IX and XII were potently inhibited with KIs in the low nanomolar range of 5-96 nM and 4-72 nM, respectively. Compounds 1d, 1j, 1v, and 1x were the most potent hCA IX inhibitors with KIs of 5.1, 8.6, 4.7, and 5.1 nM, respectively. Along with derivatives 1d and 1j, compounds 1r and 1ab potently inhibited hCA XII isoform with KIs in a single-digit nanomolar range of 8.8, 5.4, 4.3, and 9.0 nM, respectively. Compounds 1e, 1m, and 1p exhibited the best selectivity against hCA IX and hCA XII isoforms over off-target hCA II, with selectivity indexes ranging from 5 to 14.

Screening Campaign and Docking Investigations in Identifying New Hit Compounds as Inhibitors of Human Carbonic Anhydrases Expressed In Tumour Cells

The tumor-expressed human carbonic anhydrase (hCA) isoforms hCA IX and hCA XII have been extensively studied to develop anticancer agents targeting solid tumors in combined therapy. These CA  isoforms are considered key factors in controlling tumor microenvironment (TME) of cancer lines that develop high metastatic activity. Herein, we report the discovery of potent hCA IX/hCA XII inhibitors that were disclosed through a screening campaign on an in-house collection of arylsulfonamides preliminary tested toward other hCAs. Among them, the N-(4-sulfamoylphenyl)naphthalene-2-carboxamide (12) and N-(4-sulfamoylphenyl)-3,4-dihydroisoquinoline-2(1H)-carbothioamide (15) proved to be the most intriguing hCA IX/hCA XII inhibitors displaying favourable selectivity ratios over widespread hCA I and hCA II isoforms. To explore their binding mode, we conducted docking studies that described the poses of the best inhibitors in the catalytic site of hCA IX and hCA XII, thus suggesting the privileged pattern of interactions. These structural findings might further improve the knowledge for a successful identification of new sulfonamides as adjuvant agents in cancer management.

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.

Investigation of the effects of some pesticides on carbonic anhydrase isoenzymes

The aim of this study was to investigate the inhibitory effects of some pesticides known to have harmful effects on human health on carbonic anhydrase isoenzymes. Therefore, carbonic anhydrase isoenzymes (hCA I and II) were purified from human erythrocytes. The isoenzymes were purified from human erythrocytes by using an affinity column that has the chemical structure of Sepharose-4B-4-(6-amino-hexyloxy)-benzenesulfonamide. The purity of the isoenzymes was checked by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDSPAGE). It was determined that the pesticides used in this study inhibit hCA I and hCA II isoenzymes at different levels in vitro. It was determined that the strongest inhibitor for the hCA I enzyme was Carbofuran (IC50 :6.52 μM; Ki : 3.58 μM) and the weakest one was 1-Naphtol (IC50 :16.55 μM; Ki : 14.4 μM) among these pesticides. It was also found that the strongest inhibitor for the hCA II enzyme was coumatetralil (IC50 :5.06 μM; Ki : 1.62 μM) and the weakest one was Dimethachlor (IC50 14.6 μM; Ki : 8.44 μM).

Synthesis and Characterization of Novel 1,3-Diaryltriazene-Substituted Sulfaguanidine Derivatives as Selective Carbonic Anhydrase Inhibitors: Biological Evaluation, in Silico ADME/T and Molecular Docking Study

Sulfonamide compounds known as human carbonic anhydrase (hCA) inhibitors are used in the treatment of many diseases such as epilepsy, antibacterial, glaucoma, various diseases. 1,3-diaryl-substituted triazenes and sulfaguanidine are used for therapeutic purposes in many drug structures. Based on these two groups, the synthesis of new compounds is important. In the present study, the novel 1,3-diaryltriazene-substituted sulfaguanidine derivatives (SG1-13) were synthesized and fully characterized by spectroscopic and analytic methods. Inhibitory effect of these compounds on the hCA I and hCA II was screened as in vitro. All the series of synthesized compounds have been identified as potential hCA isoenzymes inhibitory with KI values in the range of 6.44±0.74-86.85±7.01 nM for hCA I and with KI values in the range of 8.16±0.40-77.29±9.56 nM for hCA II. Moreover, the new series of compounds showed a more effective inhibition effect than the acetazolamide used as a reference. The possible binding positions of the compounds with a binding affinity to the hCA I and hCA II was demonstrated by in silico studies. In conclusion, compounds with varying degrees of affinity for hCA isoenzymes have been designed and as selective hCA inhibitors. These compounds may be potential alternative agents that can be used to treat or prevent diseases associated with glaucoma and hCA inhibition.

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.

Inhibition Studies on Carbonic Anhydrase Isoforms I, II, IX, and XII with a Series of Sulfaguanidines

Two novel sulfaguanidine series, six N-(N,N'-dialkyl/dibenzyl-carbamimidoyl) benzenesulfonamide derivatives and nine N-(N-alkyl/benzyl-carbamimidoyl) benzenesulfonamide derivatives, were obtained by desulfidative amination of easily accessible dimethyl arylsulfonylcarbonimidodithioates under catalyst- and base-free conditions. The newly synthesized compounds were tested for the inhibition of four different isozymes of human carbonic anhydrase (hCA I, II, IX and XII, EC 4.2.1.1). Both series reported here were inactive against the off-target isozymes hCA I and II (K_i >100 μM). Interestingly, all investigated compounds inhibited both target isozymes hCA IX and XII in the submicromolar to micromolar ranges in which K_i values spanned from 0.168 to 0.921 μM against hCA IX and from 0.335 to 1.451 μM against hCA XII. The results indicated that N-(N-alkyl/benzyl-carbamimidoyl) benzenesulfonamides were slightly more potent inhibitors than N-(N,N'-dialkyl/dibenzyl-carbamimidoyl) benzenesulfonamides. Among the evaluated compounds, N-n-octyl-substituted N-carbamimidoylbenzenesulfonamide showed the most significant activity with a K_i value of 0.168 μM against hCA IX, which was four-fold more selective toward this isozyme versus hCA XII. Again, another derivative from N-(N-alkyl/benzyl-carbamimidoyl) benzenesulfonamide series, N-p-methylbenzyl-substituted N-carbamimidoylbenzenesulfonamide, demonstrated superior inhibitory activity against hCA XII with a K_i value of 0.335 μM.

IN SILICO STUDY OF NOVEL SULFONAMIDE DERIVATIVES BEARING A 1, 2, 4-TRIAZOLE MOIETY ACT AS CARBONIC ANHYDRASE INHIBITORS WITH PROMISING ANTI-CANCER ACTIVITY

OBJECTIVE

Aim: To evaluate the theoretical binding affinities of four synthetic compounds that target the carbonic anhydrase IX enzyme in solid tumors.

PATIENTS AND METHODS

Materials and Methods: To accurately depict the molecular structure, we utilized the Chem Draw Professional 12.0 program. We downloaded the carbonic anhydrase IX enzyme (29.25 KDa) (PDB code: 4YWP) from the Protein Data Bank into the Molecular Operating Environment software. Then, the S-score and rmsd were calculated for the proposed compounds.

RESULTS

Results: The theoretically synthesized compounds demonstrated good binding affinities with the receptor active pockets Sa, Sb, and Sd, with S-scores of -7.6491, -8.3789, and -8.3218, respectively. Substitutions improve compound orientation. The substituted triazoles ring increases flexibility and receptor interaction. In addition, the benzyl chloride derivatives play an important role in the interaction, with varying effects dependent on the groups substituted at position 4 of the benzene ring.

CONCLUSION

Conclusions: The synthesized compounds Sb with para Br substitution (S-score = -8.37) and Sd with para Cl substitution (S-score = -8.32) are considered the best ones as they exhibit a high affinity for the receptor.

Click chemistry-based synthesis of new benzenesulfonamide derivatives bearing triazole ring as selective carbonic anhydrase II inhibitors

A series of 1,2,3-triazol-1-ylbenzenesulfonamide derivatives was designed, synthesized and their ability to inhibit several carbonic anhydrase isoforms was evaluated. The basis of our design is to hybridize the benzenesulfonamide moiety widely used as a zinc-binding group, a triazole ring as spacer with a tail of different substituted aryl moieties. The synthesis of these compounds was achieved using Cu(I)-mediated click chemistry between the azide containing the benzenesulfonamide pharmacophore and various aryl acetylenes or 1,6-heptadiyne through copper-catalyzed [3+2] cycloaddition reaction. The ability the new derivatives to inhibit four human carbonic anhydrase isoforms hCA I, II, IX, and XII was evaluated. All the compounds exhibited good potency and high selectivity towards isoforms hCA I and II more than isoforms hCA IX and XII, especially for the derivatives 3c and 3j that displayed Ki of 2.8 and 3.8 nM against hCA II and a high hCA II selectivity ratio ranging from 77.6 to 3571.4 over other isoforms. All the compounds were docked in the active site of the downloaded hCA II active site and their binding pattern confirmed their significant activity by interacting of the sulfonamide moiety with zinc ion in the active site, in addition to its hydrogen bond interaction with Thr199 and Thr200. All the above-mentioned findings pointed out towards the promising activity of the synthesized series that can be presented as a new scaffold to be further optimized as selective antiglaucoma drugs.

Effects of mechanical stress and deficiency of dihydrotestosterone or 17β-estradiol on Temporomandibular Joint Osteoarthritis in mice

OBJECTIVE

To observe and analyze the interaction between excessive mechanical stress (MS) and decreased sex hormones on Temporomandibular Joint Osteoarthritis (TMJ-OA), and to discover TMJ-OA disease susceptibility genes by molecular biological analysis to elucidate part of the mechanism of TMJ-OA onset.

DESIGN

For experimental groups, orchiectomy (ORX) or ovariectomy (OVX) was performed on sexually mature 8-week-old mice. A metal plate was attached to the posterior surface of the maxillary incisors to apply excessive MS on mandibular condyles. Male mice were divided into control, ORX, MS, and ORX + MS groups, while female mice were divided into control, OVX, MS, and OVX + MS groups. Mandibular condyles were evaluated by histology and molecular biology.

RESULTS

Histomorphometric analysis of the TMJ in ORX + MS and OVX + MS groups revealed the thinnest chondrocyte layers, highest modified Mankin scores, and significant increases in the number of osteoclasts. Gene expression analysis indicated upregulation of Angptl7 and Car1 genes in the mandibular condyles of mice subjected to the combined effects of excessive MS and reduced sex hormones. In vitro analysis suggested that cartilage-like cells overexpressing Angptl7 enhanced calcification, and osteoblast-like cells overexpression Car1 suppressed cell proliferation and calcification.

CONCLUSIONS

A severe TMJ-OA mouse model was successfully developed by applying excessive MS on the mandibular condyle of male and female mice with reduced sex hormones. Disease-susceptibility genes Angptl7 and Car1 were newly discovered in the experimental groups, suggesting their involvement in the onset mechanism of TMJ-OA.

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.

Discovery of Potent Carbonic Anhydrase Inhibitors as Effective Anticonvulsant Agents: Drug Design, Synthesis, and In Vitro and In Vivo Investigations

Two sets of benzenesulfonamide-based effective human carbonic anhydrase (hCA) inhibitors have been developed using the tail approach. The inhibitory action of these novel molecules was examined against four isoforms: hCA I, hCA II, hCA VII, and hCA XII. Most of the molecules disclosed low to medium nanomolar range inhibition against all tested isoforms. Some of the synthesized derivatives selectively inhibited the epilepsy-involved isoforms hCA II and hCA VII, showing low nanomolar affinity. The anticonvulsant activity of selected sulfonamides was assessed using the maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole (sc-PTZ) in vivo models of epilepsy. These potent CA inhibitors effectively inhibited seizures in both epilepsy models. The most effective compounds showed long duration of action and abolished MES-induced seizures up to 6 h after drug administration. These sulfonamides were found to be orally active anticonvulsants, being nontoxic in neuronal cell lines and in animal models.

Design, synthesis and molecular modelling studies of some pyrazole derivatives as carbonic anhydrase inhibitors

In this study, newly synthesised compounds 6, 8, 10 and other compounds (1-5, 7 and 9) and their inhibitory properties against the human isoforms hCA I and hCA II were reported for the first time. Compounds 1-10 showed effective inhibition profiles with KI values in the range of 5.13-16.9 nM for hCA I and of 11.77-67.39 nM against hCA II, respectively. Molecular docking studies were also performed with Glide XP to get insight into the inhibitory activity and to evaluate the binding modes of the synthesised compounds to hCA I and II. More rigorous binding energy calculations using MM-GBSA protocol which agreed well with observed activities were then performed to improve the docking scores. Results of in silico calculations showed that all compounds obey drug likeness properties. The new compounds reported here might be promising lead compounds for the development of new potent inhibitors as alternatives to classical hCA inhibitors.

Carbonic anhydrase I and II autoantibody levels in primary hypertension: our preliminary results

OBJECTIVE

The pathogenesis of primary hypertension (HT) is still not completely clear, although autoimmunity has been implicated in recent years. Carbonic anhydrase (CA) is an enzyme involved in a number of important metabolic processes. CA I and II autoantibodies have been linked to various autoimmune diseases. However, CA I and II autoantibody levels in primary HT have not been previously investigated. The purpose of this study was, therefore, to investigate levels of CA I and II autoantibodies in primary HT.

PATIENTS AND METHODS

Fifty-six patients newly diagnosed with primary HT and 33 healthy individuals were included in the study. Twenty-four-hour ambulatory blood pressure monitoring was performed following office controls. Blood specimens were collected under appropriate conditions for CA I and II autoantibody level investigation and biochemical tests. Urine sodium and protein excretion were measured after 24 h. Demographic and biochemical parameters and CA I and II autoantibody levels were then compared between the patient and healthy groups.

RESULTS

CA II autoantibody and uric acid levels were significantly higher in the hypertensive group than in the control group (p=0.005, and p<0.001, respectively). CA II autoantibody (exp ß: 79.06 CI: 4.44-1407.02) (p=0.003) and uric acid elevation (exp ß: 2.10 CI: 1.31- 3.34) (p=0.002) were identified as independent predictors of HT development at logistic regression analysis.

CONCLUSIONS

CA II autoantibody levels were higher in hypertensive patients, and this elevation is an independent predictor of HT development.

Synthesis, characterization, inhibition effects, and molecular docking studies as acetylcholinesterase, α-glycosidase, and carbonic anhydrase inhibitors of novel benzenesulfonamides incorporating 1,3,5-triazine structural motifs

Some metabolic enzyme inhibitors can be used in the treatment of many diseases. Therefore, synthesis and determination of alternative inhibitors are essential. In this study, the inhibition effect of newly synthesized compounds on carbonic anhydrase (cytosolic isoforms, hCA I and hCA II), α-glycosidase (α-GLY), and acetylcholinesterase (AChE) were investigated. The possible binding mechanism of the compounds with a high inhibitory effect on the active site of the enzyme was demonstrated by molecular docking method. We investigated the inhibition effects of novel synthesized compounds (MZ1-MZ11) on metabolic enzymes such as α-GLY, AChE, and hCA I and II. The compound MZ6 for AChE, MZ8 for CA I and CA II and MZ7 for α-GLY showed a very active inhibition profile (KIs 51.67 ± 4.76 for hCA I, 40.35 ± 5.74 nM for hCA II, 41.74 ± 8.08 nM for α-GLY and 335.76 ± 46.91 nM for AChE). The novel synthesized compounds (MZ1-MZ11) have a higher enzyme (α-GLY, AChE, hCA I, and II) inhibitory potential than ACR, TAC, and AZA, respectively. The compounds may have the potential to be used as alternative medicines after further research in the treatment of many diseases such as diabetes, Alzheimer's disease, heart failure, ulcer, and epilepsy.

Activation Effects of Carnosine- and Histidine-Containing Dipeptides on Human Carbonic Anhydrases: A Comprehensive Study

l-Carnosine (β-Ala-l-His) and several other histidine-containing peptides, including two N-methylated forms on the imidazole ring (l-anserine and l-balenine), two derivatives modified on the carboxyl function (carcinine and l-carnosinamide), two analogues differing in the length of the N-terminal residue (l-homocarnosine and Gly-l-His) and the N-acetyl derivatives, were investigated as activators of four isoforms of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). The four human isoforms hCA I, II, VA and IX were activated in the low to high micromolar range, with a rather complex structure activity relationship. A performed computational study allowed us to rationalize these results and to propose a binding mode of these activators within the enzyme active site. Similarly to other CA activators, the here studied peptides could find relevant pharmacological applications such as in the management of CA deficiencies, for therapy memory and enhancing cognition or for artificial tissues engineering.

Overexpression of CA1 mRNA and the CA I Protein in Tumor Cells Does Not Change the Gene Expression of the ECM Proteins

In our study, we performed retroviral transduction to overexpress codon-optimized variant of gene encoding human carbonic anhydrase I (optiCA1) in two tumor cell lines PC3 and MDA-MB-231, derived from human prostatic and breast carcinoma respectively. We achieved significantly enhanced and stable overexpression of exogenous optiCA1 gene. The expression of endogenous, wild CA1 gene was found to be normally low (C_t 28.6 for PC3 cells) or below to the detection limit (C_t 35.5 for MDA-MB-231 cells). No morphological changes and no decreasing viability of tumor cells were observed upon stable overexpression of the optiCA1 gene. In our study we have shown that the overexpression of the optimized human CA1 in engineered PC3 and MDA-MB-231 cells did not induce similar changes as we observed in tumor cells cultivated in the presence of human sera containing extensively high titers of anti-CA I autoantibodies from patients with complete remission of malignant disease. In both optiCA1transduced cell lines, the expression of selected genes responsible for basal lamina assembly, cytoskeleton, extracellular matrix proteins and proto-oncogenes (COL1A1, COL4A4, LAMC2, CTHRC1, and WNT7B) was not changed.

Continued exploration and tail approach synthesis of benzenesulfonamides containing triazole and dual triazole moieties as carbonic anhydrase I, II, IV and IX inhibitors

A library of twenty two novel 1,2,3-triazole benzenesulfonamides incorporating thiosemicarbazide, 5(4H)-thione-1,2,4-triazole and variously substituted phenacyl appended 1,2,4-triazole as tail were designed, synthesized and assessed for their efficacy as inhibitors against carbonic anhydrase human (h) isoforms hCA I, II, IV and IX. The physiologically important and off-target cytosolic isoform hCA I was weakly inhibited by most of the newly synthesized sulfonamides while the glaucoma associated isoform hCA II was moderately inhibited with KIs spanning in low nanomolar range (KI = 8.0 nM-0.903 μM). The membrane bound isoform hCA IV, which is known to be involved in glaucoma and retinitis pigmentosa among others, was strongly inhibited by all newly synthesized sulfonamides out of which nine compounds inhibited isoform hCA IV even more effectively as compared to standard drug acetazolamide (AAZ). The membrane bound isoform hCA IX, associated with growth of tumor cells, was moderately inhibited with KIs ranging between 51 nM-3.198 μM. The effect of appending variously substituted tails on heterocyclic moieties over inhibition potential of synthesized sulfonamides is also disclosed which can be of further interest in pharmacological studies for exploring synthesis of isoform selective inhibitors.

Novel Re(I) tricarbonyl coordination compounds based on 2-pyridyl-1,2,3-triazole derivatives bearing a 4-amino-substituted benzenesulfonamide arm: synthesis, crystal structure, computational studies and inhibitory activity against carbonic anhydrase I, II, and IX isoforms†

In this work, two bidentate 2-pyridyl-1,2,3-triazole ligands (3a and 3b) containing a 4-substituted benzenesulfonamide pharmacophore prepared by classical click chemistry procedures, as well as their corresponding rhenium complexes, 4a and 4b of general formula [ReCl(CO)3(L)] (L = 3a or 3b) were prepared and fully characterised by spectroscopic methods (IR, NMR, MS, UV-Vis), elemental analysis, X-ray diffraction, and theoretical studies using DFT and TD-DFT methods. In particular, we showed that, in the solid state, the pyridine and the triazole rings of 3b adopted an uncommon cis configuration which stems from intermolecular hydrogen bonds. Preliminary assays demonstrated a promising nanomolar inhibitory activity against carbonic anhydrase isoform IX for both ligands and complexes with a strong affinity Ki of 2.8 nM for ligand 3a. More interestingly, complex 4b exhibited a pronounced selectivity against hCA IX over the off-targets hCA I and hCA II which makes this compound a promising potential anticancer drug candidate.

Pseudomonas aeruginosa β-carbonic anhydrase, psCA1, is required for calcium deposition and contributes to virulence

Calcification of soft tissue leads to serious diseases and has been associated with bacterial chronic infections. However, the origin and the molecular mechanisms of calcification remain unclear. Here we hypothesized that a human pathogen Pseudomonas aeruginosa deposits extracellular calcium, a process requiring carbonic anhydrases (CAs). Transmission electron microscopy confirmed the formation of 0.1-0.2 μm deposits by P. aeruginosa PAO1 growing at 5 mM CaCl₂, and X-ray elemental analysis confirmed they contain calcium. Quantitative analysis of deposited calcium showed that PAO1 deposits 0.35 and 0.75 mM calcium/mg protein when grown at 5 mM and 10 mM CaCl₂, correspondingly. Fluorescent microscopy indicated that deposition initiates at the cell surface. We have previously characterized three PAO1 β-class CAs: psCA1, psCA2, and psCA3 that hydrate CO₂ to HCO₃^-, among which psCA1 showed the highest catalytic activity (Lotlikar et. al. 2013). According to immunoblot and RT-qPCR, growth at elevated calcium levels increases the expression of psCA1. Analyses of the deletion mutants lacking one, two or all three psCA genes, determined that psCA1 plays a major role in calcium deposition and contributes to the pathogen's virulence. In-silico modeling of the PAO1 β-class CAs identified four amino acids that differ in psCA1 compared to psCA2, and psCA3 (T59, A61A, A101, and A108), and these differences may play a role in catalytic rate and thus calcium deposition. A series of inhibitors were tested against the recombinant psCA1, among which aminobenzene sulfonamide (ABS) and acetazolamide (AAZ), which inhibited psCA1 catalytic activity with K_Is of 19 nM and 37 nM, correspondingly. The addition of ABS and AAZ to growing PAO1 reduced calcium deposition by 41 and 78, respectively. Hence, for the first time, we showed that the β-CA psCA1 in P. aeruginosa contributes to virulence likely by enabling calcium salt deposition, which can be partially controlled by inhibiting its catalytic activity.

Sliding Window Adduct Removal Method (SWARM) for Enhanced Electrospray Ionization Mass Spectrometry Binding Data

Electrospray ionization mass spectrometry (ESI-MS) screening of compound libraries against target proteins enables the rapid identification of ligands and measurement of the stoichiometry and affinity of the interactions. However, non-specific association of buffer or salts (added or present as impurities) to the protein ions during gas-phase ion formation can complicate the analysis of ESI-MS data acquired for mixtures of compounds with similar molecular weights. Spectral overlap of ions corresponding to free protein and protein-ligand complexes and their corresponding adducts can hinder the identification of ligands and introduce errors in the measured affinities. Here, we present a straightforward approach, called the sliding window adduct removal method (SWARM), to quantitatively correct ESI mass spectra of low-to-moderate resolution for signal overlap associated with adducts. The method relies on the statistical nature of adduct formation in ESI and the assumption that the distributions of adducts associated with a given protein (free protein and ligand-bound forms) are identical at a given charge state. Analysis of ESI mass spectra measured for protein-oligosaccharide interactions using solutions that produced either low- or high-abundance adducts provides support for this assumption. Implementation of SWARM involves the stepwise subtraction of the adduct signal associated with the detected protein-ligand complexes from the mass spectrum. This is accomplished using the adduct distribution measured for an appropriate reference species (usually free protein). To demonstrate the utility of the method, we applied SWARM to ESI-MS screening data acquired for libraries of oligosaccharides and bifunctional ligands consisting of a sulfonamide moiety linked to human glycan structures. Graphical Abstract.

Novel eugenol bearing oxypropanolamines: Synthesis, characterization, antibacterial, antidiabetic, and anticholinergic potentials

Five oxypropanol amine derivatives that four of them are novel have been synthesized with high yields and practical methods. in vitro antibacterial susceptibility of Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus strains to synthesized substances were evaluated with agar well-diffusion method by comparison with commercially available drugs. Most of the bacteria were multidrug resistant. It was concluded that these compounds are much more effective than reference drugs. These eugenol bearing oxypropanolamine derivatives were also effective inhibitors against α-glycosidase, cytosolic carbonic anhydrase I and II isoforms (hCA I and II), and acetylcholinesterase (AChE) enzymes with K_i values in the range of 0.80 ± 0.24-3.52 ± 1.01 µM for hCA I, 1.08 ± 0.15-3.64 ± 0.92 µM for hCA II, 5.18 ± 0.84-12.46 ± 2.08 µM for α-glycosidase, and 11.33 ± 2.83-32.81 ± 9.73 µM for AChE, respectively.

Synthesis and bioactivities of pyrazoline benzensulfonamides as carbonic anhydrase and acetylcholinesterase inhibitors with low cytotoxicity

4-(3-Substitutedphenyl-5-polymethoxyphenyl-4,5-dihydro-1H-pyrazol-1-yl)benzenesulfonamides (9-16) were synthesized and their chemical structures were elucidated by 1H NMR, 13C NMR, and HRMS. The compounds designed include pyrazoline and sulfonamide pharmacophores in a single molecule by hibrit molecule approach which is a useful technique in medicinal chemistry in designing new compounds with potent activity for the desired several bioactivities. Inhibition potency of the sulfonamides were evaluated against human CA isoenzymes (hCA IandhCA II) and acetylcholinesterase (AChE) enzyme and also their cytotoxicities were investigated towards oral squamous cancer cell carcinoma (OSCC) cell lines (Ca9-22, HSC-2, HSC-3, and HSC-4) and non-tumor cells (HGF, HPLF, and HPC). Cytosolic hCA I and hCA II isoenzymes were inhibited by the sulfonamide derivatives (9-16) and Ki values were found in the range of 27.9 ± 3.2-74.3 ± 28.9 nM and 27.4 ± 1.4-54.5 ± 11.6 nM, respectively. AChE enzyme was strongly inhibited by the sulfonamide derivatives with Ki values in the range of 37.7 ± 14.4-89.2 ± 30.2 nM The CC50 values of the compounds were found between 15 and 200 µM towards OSCC malign cell lines. Their tumor selectivities were also calculated with two ways. Compound's selectivities towards cancer cell line were found generally low, except compounds bearing 3,4-dimethoxyphenyl 14 (TS1 = 1.3, TS2 = 1.4) and 10 (TS2 = 1.4). All sulfonamide derivatives studied here can be considered as good candidates to develop novel CAs or AChE inhibitor candidates based on the enzyme inhibition potencies with their low cytotoxicity and tumor selectivity.

Investigation of piperazines as human carbonic anhydrase I, II, IV and VII activators

Four human (h) carbonic anhydrase isoforms (CA, EC 4.2.1.1), hCA I, II, IV, and VII, were investigated for their activation profile with piperazines belonging to various classes, such as N-aryl-, N-alkyl-, N-acyl-piperazines as well as 2,4-disubstituted derivatives. As the activation mechanism involves participation of the activator in the proton shuttling between the zinc-coordinated water molecule and the external milieu, these derivatives possessing diverse basicity and different scaffolds were appropriate for being investigated as CA activators (CAAs). Most of these derivatives showed CA activating properties against hCA I, II, and VII (cytosolic isoforms) but were devoid of activity against the membrane-associated hCA IV. For hCA I, the KAs were in the range of 32.6-131 µM; for hCA II of 16.2-116 µM, and for hCA VII of 17.1-131 µM. The structure-activity relationship was intricate and not easy to rationalize, but the most effective activators were 1-(2-piperidinyl)-piperazine (KA of 16.2 µM for hCA II), 2-benzyl-piperazine (KA of 17.1 µM for hCA VII), and 1-(3-benzylpiperazin-1-yl)propan-1-one (KA of 32.6 µM for hCA I). As CAAs may have interesting pharmacologic applications in cognition and for artificial tissue engineering, investigation of new classes of activators may be crucial for this relatively new research field.

Synthesis, characterization, crystal structure of the coordination polymer Zn(II) with thiosemicarbazone of glyoxalic acid and their inhibitory properties against some metabolic enzymes

A new coordination polymer Zn(II) with thiosemicarbazone glyoxalic acid H₂GAT was obtained in this study. According to the X-ray diffraction data, the coordination of the Zn(II) ion is carried out by one sulfur atom, in the thiol form, one nitrogen atom of the azomethine group and two oxygen atoms of the carboxylate groups, one of which belongs to neighbouring complex molecule. The oxygen atom of the water molecule completes Zn(II) ion environment to a distorted square-pyramidal structure. The binding of the monomer complex into polimer occurs through the bridge oxygen atom of carboxylate group. This complex is effective inhibitor of the α-glycosidase, butyrylcholinesterase (BChE), cytosolic carbonic anhydrase I and II isoforms (hCA I and II), and acetylcholinesterase enzymes (AChE) enzymes with Ki values of 1.45 ± 0.23 µM for hCA I, 2.04 ± 0.11 µM for hCA II, 3.47 ± 0.88 µM for α-glycosidase, 0.47 ± 0.10 µM for BChE, and 0.58 ± 0.13 µM for AChE, respectively.

Discovery of potent anti-convulsant carbonic anhydrase inhibitors: Design, synthesis, in vitro and in vivo appraisal

We report the design, synthesis and pharmacological assessment of novel benzenesulfonamide derivatives acting as effective carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. All the synthesized compounds were screened for their CA inhibitory action against four isoforms of human origin (h), i.e. hCA I, hCA II, hCA VII and hCA IX. In-vitro carbonic anhydrase inhibition studies have shown that first series, 4-(2-(4-(4-substitutedpiperazin-1-yl)benzylidene)hydrazinyl)benzenesulfonamides (4a- 4i) bestowed low nanomolar range to medium nanomolar range inhibitors against hCA II and hCA VII, effectively involved in epileptogenesis. Furthermore, compounds belonging to the second series, 4-(2-(4-(4-substitutedpiperazin-yl)benzylidene)hydrazinecarbonyl)benzenesulfonamides (8a-8k) showed effective inhibition against hCA VII, being less effective against other hCA isoforms. Inspiring with obtained CA inhibition results, we have chosen some of the potent hCA II and hCA VII inhibitors (4g, 4i and 8d) to test their anti-convulsant efficacy in MES and sc-PTZ seizure tests in Swiss Albino male mice. In result, these compounds significantly attenuated both electrical (MES) as well as chemical (sc-PTZ) induced seizures. Next, in advance anticonvulsant tests, compound 8d displayed long duration of action in time course study and successfully attenuated MES induced seizure in mice up to 6 h after drug administration without showing neurotoxicity in rotarod test. Moreover, this compound was also found to be orally active and effectively abolished generalized tonic-clonic seizures in male Wistar rats upon oral administration, being non-toxic in sub acute toxicity studies.

Design and synthesis of novel benzenesulfonamide containing 1,2,3-triazoles as potent human carbonic anhydrase isoforms I, II, IV and IX inhibitors

In a quest to discover new biologically active compounds, a series of twenty novel heterocyclic derivatives substituted at position 5 with -H (7a-7j) or -CF3 (8a-8j), bearing benzenesulfonamide at N-1 position and various aroyl groups at position 4 of the 1,2,3-triazole ring was synthesized and screened for their carbonic anhydrase (CA, EC 4.2.1.1) inhibition potential against four human (h) isoforms hCA I, II, IV and IX. All the compounds (7a-7j and 8a-8j) were synthesized via [3+2] cycloaddition reaction from 4-azidobenzenesulfonamide. Interestingly, compounds 7a-7j were prepared in one pot manner via enaminone intermediate using novel methodology. All the newly synthesized compounds (7a-7j &8a-8j) were found to be excellent inhibitors of edema related isoform hCA I with their inhibition constant (Ki) ranging from 30.1 to 86.8 nM as compared to standard drug acetazolamide (AAZ) with Ki = 250 nM. Further it was found that most of tested compounds were weaker inhibitors of isoform, hCA II although compounds 7b, 7d-7e, 8a, 8d-8f, 8i (mostly with electron withdrawing substituents) have shown better inhibition potential (Ki < 50 nM). Against glaucoma associated hCA IV, compound 7d was found to be better inhibitor (Ki = 52.4 nM) than AAZ (Ki = 74 nM) while against tumor associated hCA IX, all the compounds have shown moderate inhibition potential. Present study have added one more step in exploring the 1,2,3-triazlole moiety in the medicinal field.

The effects of ex vivo ozone treatment on human erythrocyte carbonic anhydrase enzyme

Ozone autohemotherapy is used in the treatment of some diseases. Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes and play a role in homeostatic mechanisms. The aim of this study was to investigate the effects of ozone on human red blood cell CA (hCA) enzyme activity. Blood samples were treated with different doses of ozone (10, 20, 30 µg/ml) and the erythrocyte total CA activities were determined. Also, purified hCAI and hCAII isozymes were treated with the same doses of ozone and the enzyme activities were measured. About 30 µg/ml ozone treatment decreased the purified hCAI and hCAII activity and increased the total CA activity compared to the control. Because the implication of CAs on many physiological and biochemical processes is linked to pathologies, it can be suggested that the ozone at a concentration of 30 µg/ml is safely used by autohaemotherapy in a well-designed clinical trial.

Synthesis of novel 4-functionalized 1,5-diaryl-1,2,3-triazoles containing benzenesulfonamide moiety as carbonic anhydrase I, II, IV and IX inhibitors

The design, synthesis and biological evaluation of a library of 1,2,3-triazole carboxylates incorporating carboxylic acid, hydroxymethyl, carboxylic acid hydrazide, carboxamide and benzenesulfonamide moieties is disclosed. All the novel compounds were investigated for their inhibition potential against carbonic anhydrase (CA, EC 4.2.1.1) human (h) isoforms hCA I, II, IV and IX, well established drug targets. The cytosolic isoform hCA I was inhibited with Ki's ranging between 53.2 nM and 7.616 μM whereas the glaucoma associated cytosolic isoform hCA II was inhibited with Ki's in the range 21.8 nM-0.807 μM. The membrane bound isoform hCA IV, involved in glaucoma and retinitis pigmentosa among others, was effectively inhibited by some of these compounds with Ki < 60 nM, better than the reference drug acetazolamide (AAZ). The tumor associated isoform hCA IX, a recently validated antitumor/antimetastatic drug target, was also effectively inhibited by some of the new sulfonamides, which possess thus the potential to be used as tools for exploring in more details the selective inhibition of hCAs involved in various pathologies.

Synthesis, molecular modeling, and biological evaluation of 4-[5-aryl-3-(thiophen-2-yl)-4,5-dihydro-1H-pyrazol-1-yl] benzenesulfonamides toward acetylcholinesterase, carbonic anhydrase I and II enzymes

In this study, 4-[5-aryl-3-(thiophen-2-yl)-4,5-dihydro-1H-pyrazol-1-yl] benzenesulfonamides were synthesized, and inhibition effects on AChE, hCA I, and hCA II were evaluated. Ki values of the compounds toward hCA I were in the range of 24.2 ± 4.6-49.8 ± 12.8 nm, while they were in the range of 37.3 ± 9.0-65.3 ± 16.7 nm toward hCA II. Ki values of the acetazolamide were 282.1 ± 19.7 nm and 103.60 ± 27.6 nm toward both isoenzymes, respectively. The compounds inhibited AChE with Ki in the range of 22.7 ± 10.3-109.1 ± 27.0 nm, whereas the tacrine had Ki value of 66.5 ± 13.8 nm. Electronic structure calculations at M06-L/6-31 + G(d,p)//AM1 level and molecular docking studies were also performed to enlighten inhibition mechanism and to support experimental findings. Results obtained from calculations of molecular properties showed that the compounds obey drug-likeness properties. The experimental and computational findings obtained in this study might be useful in the design of novel inhibitors against hCA I, hCA II, and AChE.

Synthesis of chalcone-imide derivatives and investigation of their anticancer and antimicrobial activities, carbonic anhydrase and acetylcholinesterase enzymes inhibition profiles

The new 1-(4-(3-(aryl)acryloyl)phenyl)-1H-pyrrole-2,5-diones (5a-g) were prepared from 4'-aminchalcones (3a-g) and screened for biological activities. All compounds (3a-g and 5a-g), except 3d and 3e displayed good cytotoxic activities with IC₅₀ values in the range of 7.06-67.46 μM. IC₅₀ value of 5-fluorouracil (5-FU) was 90.36 μM. Moreover, most of compounds 5a-g showed high antibacterial activity with 8-20 mm of inhibition zone (19-25 mm of Sulbactam-Cefoperazone (SCF)). In addition, they showed good inhibitory action against acetylcholinesterase (AChE), and human carbonic anhydrase I, and II (hCA I and hCA II) isoforms. Also, these compounds demonstrated effective inhibition profiles with Ki values of 426.47-699.58 nM against hCA I, 214.92-532.21 nM against hCA II, and 70.470-229.42 nM against AChE. On the other hand, acetazolamide, clinically used drug, showed a Ki value of 977.77 ± 227.4 nM against CA I, and 904.47 ± 106.3 nM against CA II, respectively. Also, tacrine inhibited AChE showed a Ki value of 446.56 ± 58.33 nM.

Synthesis and biological evaluation of benzenesulphonamide-bearing 1,4,5-trisubstituted-1,2,3-triazoles possessing human carbonic anhydrase I, II, IV, and IX inhibitory activity

A library of benzenesulphonamides incorporating 1,2,3-triazole rings functionalised with ester, carboxylic acid, carboxamide, carboxyhydrazide, and hydroxymethyl moieties were synthesised. The carbonic anhydrase (CAs, EC 4.2.1.1) inhibitory activity of the new compounds was assessed against four human (h) isoforms, hCA I, hCA II, hCA IV, and hCA IX. Among them, hCA II and IV are anti-glaucoma drug targets, being involved in aqueous humour secretion within the eye. hCA I was inhibited with Ki's ranging between 8.3 nM and 0.8737 µM. hCA II, the physiologically dominant cytosolic isoform, was excellently inhibited by these compounds, with Ki's in the range of 1.6-9.4 nM, whereas hCA IV was effectively inhibited by most of them, with Ki's in the range of 1.4-55.3 nM. Thirteen of the twenty sulphonamides were found to be excellent inhibitors of tumour associated hCA IX with Ki's ≤ 9.5 nM. Many of the new compounds reported here showed low nM inhibitory action against hCA II, IV, and IX, isoforms involved in glaucoma and some tumours, making them interesting candidates for further medicinal chemistry/pharmacologic studies.

A class of carbonic anhydrase I - selective activators

A series of ureido and bis-ureido derivatives were prepared by reacting histamine with alkyl/aryl-isocyanates or di-isocyanates. The obtained derivatives were assayed as activators of the enzyme carbonic anhydrase (CA, EC 4.2.1.1), due to the fact that histamine itself has this biological activity. Although inhibition of CAs has pharmacological applications in the field of antiglaucoma, anticonvulsant, anticancer, and anti-infective agents, activation of these enzymes is not yet properly exploited pharmacologically for cognitive enhancement or Alzheimer's disease treatment, conditions in which a diminished CA activity was reported. The ureido/bis-ureido histamine derivatives investigated here showed activating effects only against the cytosolic human (h) isoform hCA I, having no effect on the widespread, physiologically dominant isoform hCA II. This is the first report in which CA I-selective activators were identified. Such compounds may constitute interesting tools for better understanding the physiological/pharmacological effects connected to activation of this widespread CA isoform, whose physiological function is not fully understood.

Design, synthesis, in silico and biological evaluation of novel 2-(4-(4-substituted piperazin-1-yl)benzylidene)hydrazine carboxamides

A series of novel 2-(4-(4-substituted piperazin-1-yl)benzylidene)hydrazinecarboxamide derivatives has been successfully designed and synthesized to evaluate their potential as carbonic anhydrase (CA) inhibitors. The inhibitory potential of synthesized compounds against human CAI and CAII was evaluated. Compounds 3a-n exhibited [Formula: see text] values between [Formula: see text] against CAI and [Formula: see text] against CAII. Compound 3g was the most active inhibitor, with an [Formula: see text] value of [Formula: see text] against CAII. Molecular docking studies of compound 3g with CAII showed this compound fits nicely in the active site of CAII and it interacts with the zinc ion ([Formula: see text]) along with three histidine residues in the active site. Molecular dynamics simulation studies of compound 3g complexed with CAII also showed essential interactions which were maintained up to 40 ns of simulation. In vivo sub-acute toxicity study using 3g (300 mg/kg) was found non-toxic in adult Wistar rats.

Synthesis and carbonic anhydrase inhibitory properties of novel chalcone substituted benzenesulfonamides

Carbonic anhydrases (CAs, EC 4.2.1.1) are crucial metalloenzymes involved in many bioprocesses, through catalysis of the reversible hydration/dehydration process of CO2/HCO3-. The inhibition of human CA isoforms I and II with a new series of sulfonamide derivatives incorporating substituted chalcone moieties were studied in this study. All these newly synthesized sulfonamides demonstrated important inhibitory profiles to these CA isoforms with KIs in the range of 9.88 to 55.43nM, making these compounds interesting leads, with potential applications in medicinal chemistry.

Synthesis of 4-(2-substituted hydrazinyl)benzenesulfonamides and their carbonic anhydrase inhibitory effects

In this study, 4-(2-substituted hydrazinyl)benzenesulfonamides were synthesized by microwave irradiation and their chemical structures were confirmed by (1)H NMR, (13)CNMR, and HRMS. Ketones used were: Acetophenone (S1), 4-methylacetophenone (S2), 4-chloroacetophenone (S3), 4-fluoroacetophenone (S4), 4-bromoacetophenone (S5), 4-methoxyacetophenone (S6), 4-nitroacetophenone (S7), 2-acetylthiophene (S8), 2-acetylfuran (S9), 1-indanone (S10), 2-indanone (S11). The compounds S9, S10 and S11 were reported for the first time, while S1-S8 was synthesized by different method than literature reported using microwave irradiation method instead of conventional heating in this study. The inhibitory effects of 4-(2-substituted hydrazinyl)benzenesulfonamide derivatives (S1-S11) against hCA I and II were studied. Cytosolic hCA I and II isoenzymes were potently inhibited by new synthesized sulphonamide derivatives with Kis in the range of 1.79 ± 0.22-2.73 ± 0.08 nM against hCA I and in the range of 1.72 ± 0.58-11.64 ± 5.21 nM against hCA II, respectively.

Synthesis and carbonic anhydrase inhibitory activities of new thienyl-substituted pyrazoline benzenesulfonamides

A series of new thienyl-substituted pyrazoline benzenesulfonamides were synthesized and their carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activities were tested on the human (h) isoforms hCA I and hCA II. The inhibition constant (Ki) of these sulfonamides were in the range of 232.16-637.70 nM toward the slow cytosolic isozyme hCA I, and in the range of 342.07-455.80 nM toward hCA II. Many of these compounds showed comparable inhibition with the reference sulfonamide acetazolamide, a clinically used drug. As the sulfonamide CA inhibitors (CAIs) show many therapeutic uses, these derivatives represent interesting examples of a novel class of such derivatives.

Design, synthesis and biological evaluation of N-(5-methyl-isoxazol-3-yl/1,3,4-thiadiazol-2-yl)-4-(3-substitutedphenylureido) benzenesulfonamides as human carbonic anhydrase isoenzymes I, II, VII and XII inhibitors

A series of N-(5-methyl-isoxazol-3-yl/1,3,4-thiadiazol-2-yl)-4-(3-substitutedphenylureido) benzenesulfonamide derivatives has been designed, synthesized and screened for their in vitro human carbonic anhydrase (hCA; EC 4.2.1.1) inhibition potential. These newly synthesized sulfonamide compounds were assessed against isoforms hCA I, II, VII and XII, with acetazolamide (AAZ) as a reference compound. The majority of these compounds were found quite weak inhibitor against all tested isoforms. Compound 15 showed a modest inhibition potency against hCA I (Ki = 73.7 μM) and hCA VII (Ki = 85.8 μM). Compounds 19 and 25 exhibited hCA II inhibition with Ki values of 96.0 μM and 87.8 μM, respectively. The results of the present study suggest that, although the synthesized derivatives have weak inhibitory potential towards all investigated isoforms, some of them may serve as lead molecules for the further development of selective inhibitors incorporating secondary sulfonamide functionalities, a class of inhibitors for which the inhibition mechanism is poorly understood.

Antibodies reacting to carbonic anhydrase isozymes (I and II) and albumin in sera from dogs

IgGs to carbonic anhydrase isozymes (CA-I and CA-II) and albumin were identified in dog serum. IgG titers were determined in the sera of asymptomatic dogs, and in dogs with atopic dermatitis, diarrhea and/or vomiting, diabetes and/or pancreatitis, kidney disease, hepatic disease, and thyroid gland disease, using ELISA. Low titres of IgG-reactive CA-I, CA-II, BSA, and CSA were found in the sera of healthy beagles. Compared with healthy beagles, there was a significant difference in the titers of antibodies against CA-I in asymptomatic dogs, dogs with diabetes and/or pancreatitis, or thyroid gland disease, or hepatic disease. Compared with healthy beagles, there was a significant difference in the antibody titer of anti-CA-II IgG in asymptomatic dogs and in those with hepatic disease. There was a significant difference in the antibody titer of anti-BSA IgG between healthy beagles and dogs with hepatic disease.

Mass spectrometry-based monitoring of millisecond protein-ligand binding dynamics using an automated microfluidic platform

Characterizing protein-ligand binding dynamics is crucial for understanding protein function and for developing new therapeutic agents. We present a novel microfluidic platform that features rapid mixing of protein and ligand solutions, variable incubation times, and an integrated electrospray ionization source for mass spectrometry-based monitoring of protein-ligand binding dynamics. This platform offers many advantages, including solution-based binding, label-free detection, automated operation, rapid mixing, and low sample consumption.

Sulfonamide inhibition studies of the β-carbonic anhydrase from the newly discovered bacterium Enterobacter sp. B13

The genome of the newly identified bacterium Enterobacter sp. B13 encodes for a β-class carbonic anhydrases (CAs, EC 4.2.1.1), EspCA. This enzyme was recently cloned, and characterized kinetically by this group (J. Enzyme Inhib. Med. Chem. 2016, 31). Here we report an inhibition study with sulfonamides and sulfamates of this enzyme. The best EspCA inhibitors were some sulfanylated sulfonamides with elongated molecules, metanilamide, 4-aminoalkyl-benzenesulfonamides, acetazolamide, and deacetylated methazolamide (KIs in the range of 58.7-96.5nM). Clinically used agents such as methazolamide, ethoxzolamide, dorzolamide, brinzolamide, benzolamide, zonisamide, sulthiame, sulpiride, topiramate and valdecoxib were slightly less effective inhibitors (KIs in the range of 103-138nM). Saccharin, celecoxib, dichlorophenamide and many simple benzenesulfonamides were even less effective as EspCA inhibitors, with KIs in the range of 384-938nM. Identification of effective inhibitors of this bacterial enzyme may lead to pharmacological tools useful for understanding the physiological role(s) of the β-class CAs in bacterial pathogenicity/virulence.

Pyridazinone substituted benzenesulfonamides as potent carbonic anhydrase inhibitors

A series of sulfonamide derivatives (2a-l) incorporating substituted pyridazinone moieties were investigated for the inhibition of two human cytosolic carbonic anhydrase isoforms, hCA I and hCA II. All these compounds, together with the clinically used sulfonamide acetazolamide were investigated as inhibitors of the physiologically relevant isozymes I and II. These sulfonamides showed very strong inhibition against all these isoforms with K(I)'s in the range of 0.98-8.5 nM which makes such molecules possible to be used as leads for discovery of novel effective CA inhibitors targeting other isoforms with medicinal chemistry applications.