Carbonic anhydrases: novel therapeutic applications for inhibitors and activators

Physiological role of bicarbonate in microbes: A double-edged sword?

HCO3- is involved in pH homoeostasis and plays a multifaceted role in human health. HCO3- has been recognized for its antimicrobial properties and is pivotal in bacterial antibiotic susceptibility. Notably, the interconversion between CO2 and HCO3-, facilitated by the enzyme carbonic anhydrase (CA), is crucial in tissues infected by pathogens. Studies have highlighted the antimicrobial potency of CA inhibitors, emphasizing the importance of this enzyme in this area. The potential of HCO3- as an antibiotic adjuvant is evident; its ability to increase virulence in pathogens such as Enterococcus faecalis and Mycobacterium tuberculosis requires meticulous scrutiny. HCO3- modulates bacterial behaviours in diverse manners: it promotes Escherichia coli O157:H7 colonization in the human gut by altering specific gene expression and, with Pseudomonas aeruginosa, amplifies the effect of tobramycin on planktonic cells while promoting biofilm formation. These multifaceted effects necessitate profound mechanistic exploration before HCO3- can be considered a promising clinical adjuvant.

Two-photon photosensitizer for specific targeting and induction of tumor pyroptosis to elicit systemic immunity-boosting anti-tumor therapy

Photodynamic therapy (PDT) has garnered increasing attention in cancer treatment due to its precise spatiotemporal selectivity and non-invasive nature. However, several challenges, including the inability of photosensitizers to discriminate between tumor and healthy tissues, as well as the limited tissue penetration depth of light sources, impede its broader application. To surmount these impediments, our research introduces a two-photon photosensitizer (TPSS) that specifically targets tumor overexpressing carbonic anhydrase IX (CA IX), thereby exhibiting exceptional specificity for tumor cells. Under two-photon laser stimulation, TPSS generates a large amount of reactive oxygen species (ROS), inducing cell pyroptosis and subsequently triggering a strong anti-tumor immune response. Additionally, proteomics analysis provides compelling evidence to elucidate the anti-tumor mechanism of TPSS in vivo. Through comprehensive immune assessments, TPSS under two-photon laser irradiation effectively activates both the innate and adaptive immune systems, efficiently suppressing the proliferation of distant metastatic tumors, underscoring its considerable therapeutic potential. Collectively, this study provides a viable strategy to overcome the limitations of PDT, highlighting the prospects of two-photon excitation photosensitizers.

In vivo MRI of breast cancer using carbonic anhydrase IX proteoglycan-like domain -targeting liposomes

Molecular imaging of breast cancer is increasingly recognized as a valuable tool for optimizing therapeutic interventions. Among potential targets for molecular imaging reporters, Carbonic Anhydrase IX (CAIX) stands out for its overexpression in tumors characterized by large hypoxic areas and aggressive phenotypes. CAIX, a transmembrane glycoprotein involved in pH regulation, displays a unique proteoglycan-like (PG) domain, not present in other isoforms, that could represent a specific target for imaging and therapy. While high sensitivity imaging techniques such as Positron Emission Tomography (PET) and optical imaging have been applied for CAIX targeting, no in vivo study utilizing Magnetic Resonance Imaging (MRI) to target CAIX has yet been reported. Herein, we address this gap by applying CAIX PG-targeting functionalized liposomes in the first in vivo MRI study on a murine model of breast cancer. TS/A cells were subcutaneously injected to generate primary tumors in mice, and targeted liposomes were delivered intravenously after 15 days. Internalization of the targeted liposomes by receptor-mediated endocytosis led to an enhanced MRI signal in the tumor region. Cytoplasmic and endosomal distribution of the liposomes' payload was observed. Conversely, non-functionalized liposomes and liposomes bearing a scrambled peptide, while entering tumor cells in smaller amounts, localized only to endosomes as expected. The findings reported herein suggest that CAIX PG domain-targeting liposomal formulations exploiting receptor-mediated endocytosis can lead to improved diagnostic capabilities and open avenues for targeted therapeutic delivery for the treatment of tumors overexpressing CAIX, particularly breast cancer.

Identification of new 1,2,3-Triazole analogues of sulfanilamide as inhibitors of the carbonic anhydrase II enzyme: Comprehensive in-vitro and in-vivo analyses

Carbonic anhydrases (CAs) play a vital role in various physiological processes by catalyzing the reversible hydration of CO2 into HCO3-, hence maintaining the fluid and pH balance. Overexpression of carbonic anhydrases II (CA II) is associated with diseases, such as glaucoma, and epilepsy; therefore, it is considered as an important clinical target. Therapeutically used CA inhibitors exhibit several undesirable effects; therefore, there is an urgent need to identify new, safe, and effective inhibitors of the CAs. Keeping in view the importance of CA II inhibition, a library of new 1,3-disubstituted-1,2,3-triazole analogues of sulfanilamide is synthesized via Click chemistry, starting from sulfanilamide azide and different substituted propargyl ethers, incorporating benzyl and heteroarylmethyl moieties. The new derivatives showed significant CA II inhibitory activity (IC50 ranging between 0.19 0.66 μM) when compared with the standard inhibitor, acetazolamide (0.13 ± 0.01 μM). Among all, compounds 16 and 17 showed the most potent activity (IC50 = 0.19 μM) followed by compounds 23, and 18 (IC50 = 0.24 ± 0.014 and 0.26 ± 0.04 μM, respectively). Kinetics studies showed that all compounds are competitive inhibitors of bCA II enzyme (Ki ranging between 0.14-0.68 μM). Additionally, molecular docking studies revealed that all compounds formed network of interactions with the active site residues of the bCA II enzyme. All compounds were found to be non-toxic against BJ Human fibroblast cells. From in-vivo studies, we found that CA activity was significantly inhibited by the intraperitoneal administration of compounds 16 and 17 for up to 5 h. In conclusion, new 1,2,3-triazole analogues of sulfanilamide were identified as good CA II inhibitors.

Sulfonamide-Bearing Pyrazolone Derivatives as Multitarget Therapeutic Agents: Design, Synthesis, Characterization, Biological Evaluation, In Silico ADME/T Profiling and Molecular Docking Study

The research and design of new inhibitors for the treatment of diseases such as Alzheimer's disease and glaucoma through inhibition of cholinesterases (ChEs; acetylcholinesterase, AChE and butyrylcholinesterase, BChE) and carbonic anhydrase enzymes are among the important targets. Here, a series of novel sulfonamide-bearing pyrazolone derivatives (1a-f and 2a-f) were successfully synthesized and characterized by using spectroscopic and analytical methods. The inhibitory activities of these newly synthesized compounds were evaluated both in vitro and in silico for their effect on carbonic anhydrases (hCA I and hCA II isoenzymes) and ChEs. The in vitro studies showed that these novel compounds demonstrated potential inhibitory activity, with KI values covering the following ranges: 18.03 ± 2.86-75.54 ± 4.91 nM for hCA I, 24.84 ± 1.57-85.42 ± 6.60 nM for hCA II, 7.45 ± 0.98-16.04 ± 1.60 nM for AChE, and 34.78 ± 5.88-135.70 ± 17.39 nM for BChE. Additionally, many of these compounds showed promising inhibitory activity, and some showed higher potency than reference compounds. While the in silico studies have also identified the potential binding positions of these compounds, using the crystal structures of hCA I, II, AChE and BChE receptors. The varying affinities demonstrated by these designed compounds for ChEs and hCA isoenzymes show that these compounds could hold promise as potential alternative agents for selectively inhibiting ChEs and hCAs in the treatment of diseases such as Alzheimer's disease and glaucoma.

4D printing chemical stimuli-responsive hydrogels for tissue engineering and localized drug delivery applications - part 2

INTRODUCTION

The incorporation of 4D printing alongside chemical stimuli-responsive hydrogels represents a significant advancement in the field of biomedical engineering, effectively overcoming the constraints associated with conventional static 3D-printed structures. Through the integration of time as the fourth dimension, 4D printing facilitates the development of dynamic and adaptable structures that can react to chemical alterations in their surroundings. This innovation presents considerable promise for sophisticated tissue engineering and targeted drug delivery applications.

AREAS COVERED

This review examines the function of chemical stimuli-responsive hydrogels within the context of 4D printing, highlighting their distinctive ability to undergo regulated transformations when exposed to particular chemical stimuli. An in-depth examination of contemporary research underscores the collaborative dynamics between these hydrogels and their surroundings, focusing specifically on their utilization in biomimetic scaffolds for tissue regeneration and the advancement of intelligent drug delivery systems.

EXPERT OPINION

The integration of 4D printing technology with chemically responsive hydrogels presents exceptional prospects for advancements in tissue engineering and targeted drug delivery, facilitating the development of personalized and adaptive medical solutions. Although the potential is promising, it is essential to address challenges such as material optimization, biocompatibility, and precise control over stimuli-responsive behavior to facilitate clinical translation and scalability.

Novel 1,2,4-triazole-derived Schiff base derivatives: Design, synthesis, and multi-enzyme targeting potential for therapeutic applications

This study synthesized a series of Schiff base derivatives featuring a 1,2,4-triazole framework and characterized through FT-IR, 1H NMR, 13C NMR, 19F NMR, MS, and elemental analysis. Subsequently, the inhibitory activities of these compounds were systematically evaluated in vitro against human carbonic anhydrase (hCA) isozymes I and II, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE). The results revealed that compounds 5a and 5c were particularly effective against cholinesterase enzymes, demonstrating their potential for neuroprotective applications. Meanwhile, compounds 5f and 5g exhibited remarkable inhibition of hCA I and II isozymes, suggesting their promise as selective inhibitors for therapeutic areas. Furthermore, molecular docking analyses revealed strong and specific interactions between the active compounds and enzyme binding sites, further supported by molecular dynamics simulations. Additionally, ADMET profiling of all compounds indicated favourable pharmacokinetic properties. The ADMET results suggest that these compounds hold significant potential for clinical applications in central nervous system and various disorders. These findings strongly suggest that the synthesized compounds are promising candidates for addressing unmet therapeutic needs in neurodegenerative and metabolic disorders, with potential applications in multi-enzyme targeting therapies.

Synthesis, molecular docking and molecular dynamics simulations, drug-likeness studies, ADMET prediction and biological evaluation of novel pyrazole-carboxamides bearing sulfonamide moiety as potent carbonic anhydrase inhibitors

Pyrazoles are unique bioactive molecules with a versatile biological profile and they have gained an important place on pharmaceutical chemistry. Pyrazole compounds containing sulfonamide nuclei also attract attention as carbonic anhydrase (CA) inhibitors. In this study, a library of pyrazole-carboxamides were synthesized and the structures of the synthesized molecules were characterized using FT-IR, 1H-NMR, 13C-NMR and HRMS. Then the inhibition effects of newly synthesized molecules on human erythrocyte hCA I and hCA II isoenzymes were investigated. Ki values of the compounds were in the range of 0.063-3.368 µM for hCA I and 0.007-4.235 µM for hCA II. Molecular docking studies were performed between the most active compounds 6a, 6b and the reference inhibitor, acetazolamide (AAZ) and the hCA I and hCA II receptors to investigate the binding mechanisms between the compounds and the receptors. These compounds showed better interactions than the AAZ. ADMET analyzes were performed for the compounds and it was seen that the compounds did not show AMES toxicity. The stability of the molecular docking results over time was analysed by 50 ns molecular dynamics simulations. Molecular dynamics simulations revealed that 6a and 6b exhibited good stability after docking to the binding sites of hCA I and hCA II receptors, with minor conformational changes and fluctuations.

Polypharmacology of carbonic anhydrase inhibitors and activators

INTRODUCTION

Carbonic anhydrases (CAs) are enzymes involved in many physiologic and pathological processes connected with a diversity of conditions. Many of their inhibitors are used clinically for the management of glaucoma, epilepsy, obesity, and cancer. Some of these compounds also show significant polypharmacological effects. CA activators (CAAs) are not in clinical use.

AREAS COVERED

PubMed and ScienceDirect databases were searched for articles published over the past 20 years. Several antiepileptics (topiramate, zonisamide, lacosamide, and levetiracetam), some atypical antipsychotics (sulpiride, veralipride), celecoxib, polmacoxib, pazopanib, the antiulcer agent famotidine, and compounds in clinical trials (epacadostat and PCI-27483) as antitumor agents significantly inhibit several CA isoforms of the 15 human ones, apart their action on several other targets. The possible role of CA inhibition in the therapeutic effects of these drugs, their side effects, and the possibility to use this information for drug design are discussed. CAAs belonging to a variety of aminergic classes (histaminergic, dopaminergic, and serotoninergic) are also discussed.

EXPERT OPINION

Polypharmacology involving CA inhibitors/CAAs is understood from the chemical, structural, and pharmacological viewpoints. The many other drug targets with which these modulators of activity interact allow for de novo design of such agents for the management of multifactorial conditions in need of innovative drugs.

Exploration of Aromatic Hydrazides as Inhibitors of Human Carbonic Anhydrases

A large set of hydrazide-based derivatives were explored as inhibitors of the human (h) carbonic anhydrase (CA) isoforms I, II, IV, IX, and XII. A wide series of compounds were synthesized and then assessed for their CA inhibitory activity using a CO2 hydrase stopped-flow assay. Generally, these inhibitors demonstrated micromolar activity against the evaluated hCAs. Specifically, some derivatives bearing a ureido-linker exhibited the highest inhibitory potency, showing inhibition constants (KIs) in the low-micromolar range against hCAs IV, XI, and XII. Moreover, two of them were detected as submicromolar inhibitors of isoform IV (KIs: 0.8-0.96 µM). Molecular modeling was carried out to investigate the binding mode of the most selective and potent compounds and reinforce the experimental results. The latter suggests that hydrazide compounds act as zinc binders, being bidentate ligands, and can be developed as an alternative to classic CA inhibitors.

Computational drug design for neurosyphilis disease by targeting Phosphoglycerate Kinase in Treponema pallidum with enhanced binding affinity and reduced toxicity

Neurosyphilis, a severe neurological complication of syphilitic infection caused by the gram-negative spirochete Treponema pallidum poses significant challenges in treatment due to its irregular physiology and lack of efficacy in present therapeutic strategies. Here, we report a new approach to developing drug treatment that targets the enzyme phosphoglycerate kinase (PGK), an essential component of the T. pallidum glycolytic pathway. Therefore, a ligand was designed involving common neuroprotectant elements reported from literature by a computational drug design method, to increase their binding energy with lower toxicity. The calculated binding affinity of the designed ligand with PGK was analyzed by molecular docking to be - 116.68 kcal/mol. Also, interaction analysis predicted that there are 5 hydrophobic bonds and 3 hydrogen bonds present between the docked complex. Afterward, in-silico ADMET studies were conducted for the designed ligand that determined a strong pharmacological profile with good absorption, zero violation of Lipinski's rule, and non-toxic properties. DFT analysis further optimized the ligand with a HOMO/LOMO gap value of 0.01421 kcal/mol indicating higher reactivity and enhanced electronic interactions, improving ligand efficiency. Moreover, pharmacophore modeling confirmed the reactive nature of the ligand. Furthermore, MD simulations showed stability in the overall structure. The output shows that our optimized ligand has statistically better binding affinity than the currently used drug penicillin, with improved pharmacokinetic profiles. This work demonstrates the importance of ligand design for the discovery of new drugs to treat neurosyphilis.

Molecular Determinants of Affinity and Isoform Selectivity in Protein─Small Molecule Hybrid Inhibitors of Carbonic Anhydrase

Multiple studies have demonstrated the benefit of engineering hybrid ligands that combine the unique benefits of small molecules and proteins or peptides. However, the molecular complexity of hybrid ligands generates a parameter space so large it cannot be exhaustively explored. We systematically evaluated the impact of one molecular design element, conjugation site, on the discovery of functional protein-small molecule hybrids (PriSMs). We utilized a library of yeast-displayed fibronectin domain variants with amino acid and loop length diversity in the paratope and a single cysteine at one of 18 possible conjugation sites. The protein variants were coupled with maleimide-functionalized acetazolamide and sorted via competitive flow cytometry to discover potent and selective inhibitors of three isoforms of carbonic anhydrase. Deep sequencing of the resultant populations of functional PriSMs revealed an isoform-dependent distribution of conjugation site preferences. The top PriSMs showed potency and selectivity gains up to 23- and 100-fold (in this case, for CA-II vs CA-XII, with a 43-fold selectivity gain for CA-II vs CA-IX) relative to PEG2-acetazolamide alone. The presented study expands our fundamental understanding of the role of conjugation site in PriSM function and informs future PriSM engineering efforts by highlighting the benefit of conjugation site diversity in PriSM libraries.

Molecular dynamics simulation reveals structural insights into isozyme selectivity of carbonic anhydrase XII inhibitors in hypoxic tumor microenvironment

Human carbonic anhydrase (CA) isoenzymes IX and XII are overexpressed in cancer cells, contributing to tumor microenvironment acidification and representing important targets for cancer therapy. In this study, we identified compound V35 (ZINC09419065) as a selective inhibitor of CA IX and CA XII with enhanced binding stability and selectivity compared to standard inhibitors. We analyzed conserved regions in CA I, CA II, CA IX, and CA XII to investigate their isozyme selectivity, revealing critical selectivity determinants at positions 95, 141, and 203. Molecular docking results indicated that V35 interacts robustly with CA XII, forming a metal ion coordination complex with Zn via HIS94, HIS96, HIS119, and THR199, similar to the interaction pattern of standard inhibitor SLC-0111. Molecular dynamics (MD) simulations conducted over 500 ns under hypoxic conditions showed that V35 has high binding stability, with root mean square deviation (RMSD) and fluctuation (RMSF) values comparable to SLC-0111, demonstrating its conformational stability in CA XII. Binding free energy calculations using the MMGBSA method showed that V35 achieves binding free energy of -44.17 kcal/mol with CA XII, closely matching SLC-0111 (-49.41 kcal/mol). Density functional theory (DFT) calculations further highlighted V35's electrostatic potential distribution, supporting its isozyme selectivity. Post-dynamics analysis indicated that the ester functional groups and the inward movement of HIS64 stabilize V35's interactions in CA XII, a feature absent in CA I.

Hi-C profiling in tissues reveals 3D chromatin-regulated breast tumor heterogeneity informing a looping-mediated therapeutic avenue

The limitations of Hi-C (high-throughput chromosome conformation capture) profiling in in vitro cell culture include failing to recapitulate disease-specific physiological properties and lacking a clinically relevant disease microenvironment. In this study, we conduct Hi-C profiling in a pilot cohort of 12 breast tissues comprising two normal tissues, five ER+ breast primary tumors, and five tamoxifen-treated recurrent tumors. We demonstrate 3D chromatin-regulated breast tumor heterogeneity and identify a looping-mediated target gene, CA2, which might play a role in driving tamoxifen resistance. The inhibition of CA2 impedes tumor growth both in vitro and in vivo and reverses chromatin looping. The disruption of CA2 looping reduces tamoxifen-resistant cancer cell proliferation, decreases CA2 mRNA and protein expression, and weakens the looping interaction. Our study thus provides mechanistic and functional insights into the role of 3D chromatin architecture in regulating breast tumor heterogeneity and informs a new looping-mediated therapeutic avenue for treating breast cancer.

Hippocampus carbonic anhydrase 1 via ERK pathway may be involved in depressive like behaviors

Major depressive disorder (MDD) is a destructive mental disease, yet the mechanism is still not clear. Carbonic anhydrase, an efficient catalyst for CO2 conversion to carbonate and protons, could affect many functions, such as memory formation recognition. Lately, we illustrated that carbonic anhydrase 1 (CAR1) knockout (CAR1-/-) mice could lead to depressive-like behaviors, but the underlying molecular mechanism is unknown. Herein, we attempted to explore whether CAR1 knockout could result in transcriptional changes thus involve in depressive like behaviors. The present study revealed that compared with WT mice, the CAR1 Knockout (CAR1-/-) mice led to depressive-like behavior. According to the microarray profiling, a couple of disturbed signaling pathways are found in CAR1-/- mice. Proteins like GluR1 and GABA Aα1 were validated compared to control groups by western blotting, while NMDAR 2A was increased in RNA level compared to the control group. More interestingly, the proteins might be related to the ERK signal pathway, MAPK, and RSK decreased in protein level compared to the control group. Moreover, this decline could be restored when CAR1 was overexpressed in the ventral hippocampus of CAR1-/- mice and depressive-like phenotypes were also rescued. Our dataset suggests that CAR1 might influence depressive-like behavior through the ERK signal pathway, which may provide novel insights and evidences to MDD study.

Structural Studies of the Dopamine D4 Receptor Antagonist Sonepiprazole as an Inhibitor of Human Carbonic Anhydrases

In this study, we provide the first evidence that sonepiprazole, a dopamine D4 receptor antagonist, acts as a potent inhibitor of human carbonic anhydrases (hCAs). Sonepiprazole exhibited significant inhibitory activity across the panel of catalytically active hCAs, with the exception of hCA IV, and hCA III. The most potent inhibition was observed against the brain-associated isoform hCA VII, with a K I of 2.9 nM. Insights from X-ray crystallographic structures of the complexes with hCA I, hCA II, and hCA XII revealed that the sulfonamide group of sonepiprazole coordinates the zinc ion in the active site, a typical interaction for this class of inhibitors. Despite the presence of isoform-specific residues at the rim of the active site pocket, these variations seem not to significantly impact the compound overall inhibition potency. These findings highlight a dual functionality of sonepiprazole as both a D4 receptor antagonist and a carbonic anhydrase inhibitor.

Carbon dioxide regulates Mycobacterium tuberculosis PhoPR signaling and virulence

The Mycobacterium tuberculosis (Mtb) two-component regulatory system PhoPR is implicated in pH sensing within the macrophage because it is strongly induced by acidic pH both in vitro and the macrophage phagosome. The carbonic anhydrase (CA) inhibitor ethoxzolamide inhibits PhoPR signaling supporting the hypothesis that CO2 may also play a role in regulating PhoPR. Here, we show that increasing CO2 concentration induces PhoPR signaling, at both pH 7.0 and pH 5.7. At acidic pH 5.7, a normally strong inducer of PhoPR signaling, increasing CO2 from 0.5% to 5% further induces the pathway, showing CO2 acts synergistically with acidic pH to induce the PhoPR regulon. Based on these findings, we propose that PhoPR functions as a CO2 sensor. Mtb has three CA (CanA, CanB, and CanC), and using CRISPR interference knockdowns and gene deletion mutants, we assessed which CAs regulate PhoPR signaling and macrophage survival. We first examined if CA played a role in Mtb pathogenesis and observed that CanB was required for survival in macrophages, where the knockdown strain had ~1-log reduction in survival. To further define the interplay of CO2 and Mtb signaling, we conducted transcriptional profiling experiments at varying pH and CO2 concentrations. As hypothesized, we observed that the induction of PhoPR at acidic pH is dependent on CO2 concentration, with a subset of core PhoPR regulon genes dependent on both 5% CO2 and acidic pH for their induction, including expression of the ESX-1 secretion system. Transcriptional profiling also revealed core CO2-responsive genes that were differentially expressed independently of the PhoPR regulon or the acidic pH-inducible regulon. Notably, genes regulated by a second two-component regulatory system, TrcRS, are associated with adaptation to changes in CO2.

Carbonic anhydrase inhibitors prevent presymptomatic capillary flow disturbances in a model of cerebral amyloidosis

INTRODUCTION

Disturbances in microvascular flow dynamics are hypothesized to precede the symptomatic phase of Alzheimer's disease (AD). However, evidence in presymptomatic AD remains elusive, underscoring the need for therapies targeting these early vascular changes.

METHODS

We employed a multimodal approach, combining in vivo optical imaging, molecular techniques, and ex vivo magnetic resonance imaging, to investigate early capillary dysfunction in C57BL/6-Tg(Thy1-APPSwDutIowa)BWevn/Mmjax (Tg-SwDI) mice without memory impairment. We also assessed the efficacy of carbonic anhydrase inhibitors (CAIs) in preventing capillary flow disturbances.

RESULTS

Our study revealed capillary flow disturbances associated with alterations in capillary morphology, adhesion molecule expression, and amyloid beta (Aβ) load in 9- to 10-month-old Tg-SwDI mice without memory impairment. CAI treatment ameliorated these capillary flow disturbances, enhanced oxygen availability, and reduced Aβ load.

DISCUSSION

These findings underscore the importance of capillary flow disturbances as early biomarkers in presymptomatic AD and highlight the potential of CAIs for preserving vascular integrity in the early stages of AD.

HIGHLIGHTS

Uncovered early capillary dysfunction in a presymptomatic Alzheimer's disease (AD) mouse model. Evidence linking capillary stalls and capillary dysfunction with oxygen delivery issues in AD. Novel use of carbonic anhydrase inhibitors to prevent early capillary flow disturbances in AD.

Carbonic anhydrase inhibitors: Structural insights and therapeutic potential

Carbonic anhydrase inhibitors (CAIs) have garnered significant attention in recent years due to their critical role in managing various diseases, including glaucoma, epilepsy, cancer, and other conditions linked to carbonic anhydrase (CA) isoforms. This review highlights the recent advancements in the design and development of CAIs, focusing on diverse chemical classes such as indoles, sulfocoumarins, 1,2,3-triazoles, urea derivatives, chalcones, quinolines, and pyridines. Each class presents unique structural features and mechanisms of action, contributing to the selective inhibition of specific CA isoforms. The ongoing exploration of these compounds has not only enhanced our understanding of CA inhibition but also opened new avenues for therapeutic applications, paving the way for the development of novel drugs that tackle pressing healthcare challenges.

Investigating the Anti-Inflammatory Potential of SLC-0111: A Carbonic Anhydrase Inhibitor Targeting Cyclooxygenase-Mediated Inflammatory Pathways in a Carrageenan-Induced Rat Model

Inflammation is a fundamental physiological reaction that leads to the development of many diseases, including tissue damage, asthma, diabetes, atherosclerosis, inflammatory bowel disease, and cancer. The enzyme COX is a vital mediator in inflammatory processes. Interestingly, the COX enzyme possesses multiple structural similarities to the carbonic anhydrase enzyme. SLC-0111, a molecule known for its potent and selective inhibition of carbonic anhydrase, has not yet been studied for its potential effects on acute inflammation, proinflammatory cytokine levels, or oxidative stress parameters. Our study seeks to assess the binding affinity of SLC-0111 to the COX enzyme, as well as its possible anti-inflammatory properties. We treated rats SLC-0111 at dosages of 50, 100, and 200 mg/kg for 3 days before generating inflammation with carrageenan (CAR). Following CAR delivery, paw thickness was evaluated at 4-h intervals to assess inflammatory levels. Additionally, protein extravasation in paw tissue has been examined using Evans Blue (EB) dye. MDA and glutathione (GSH) levels in paw tissue were measured to assess oxidative stress. Carrageenan enhanced edema, protein extravasation, and proinflammatory cytokines TNF-α, IL-1β, IL-6, IL-4, and IL-13. SLC-0111 decreased all of these, except for IL-4. Similarly, the histological findings of our research indicated that SLC-0111 had an anti-inflammatory effect at a dose of 200 mg/kg. However, SLC-0111 had no significant effect on MDA or GSH levels. These data represent that SLC-0111 may have anti-inflammatory properties and could be used as a treatment for inflammation-related disorders.

Anticholinesterase and carbonic anhydrase inhibitory activities of natural carnosic acid derivatives: A comprehensive in vitro and in silico study

This study investigates the anticholinesterase (acetylcholinesterase [AChE] and butyrylcholinesterase [BChE]) and carbonic anhydrase (CAI and CAII) inhibitory activities of carnosic acid and its natural derivatives, including carnosol, rosmanol, 7-methoxy-rosmanol, 12-methoxy-carnosic acid, and isorosmanol. Among the tested compounds, rosmanol demonstrated exceptional potency, with IC50 values of 0.73 nM for AChE and 0.75 nM for BChE, significantly outperforming tacrine. Rosmanol also exhibited remarkable inhibition of CA I (IC50 = 0.21 nM), surpassing acetazolamide by over 450-fold, and moderate inhibition of CAII. Molecular docking and molecular mechanics generalized born surface area (MM-GBSA) studies revealed strong binding affinities for rosmanol, with docking scores of -11.757 kcal/mol (AChE) and -11.465 kcal/mol (BChE). The MM-GBSA binding free energy calculations further confirmed stable interactions for CA I (-63.24 kcal/mol) and AChE (-60.09 kcal/mol). Molecular dynamics simulations over 50 ns showed stable enzyme-ligand complexes, particularly for AChE and BChE (root mean square deviation ~1.5 Å), with key residues identified as crucial for stabilization. Other derivatives also displayed significant inhibitory activities, suggesting their potential as secondary leads. The ADMET analysis showed favorable pharmacokinetics and rosmanol emerged as a promising candidate. This comprehensive study highlights rosmanol as a multitarget therapeutic agent with potent anticholinesterase and CA inhibitory properties, offering promise for treating neurodegenerative and metabolic disorders.

Pharmacological inhibition of carbonic anhydrases with a positively charged pyridinium sulfonamide phenocopies the neuroprotective effects of Car9 genetic ablation in a murine setting of oxygen/glucose deprivation followed by re-oxygenation and is associated with improved neuronal function in ischemic rats

Carbonic anhydrases constitute a family of metalloenzymes vital for maintaining acid-base balance and regulating pH in physio-pathological processes. These findings suggest carbonic anhydrases as potential therapeutic targets for treating pH-associated disorders, including cerebral ischemia, to mitigate hypoxia- and reoxygenation-induced neuronal damage. A focus on carbonic anhydrase IX showed that ischemic stress altered subcellular distributions of this enzyme in rodent neuronal populations. Given the enzyme's canonical membrane localization, we implemented pharmacological inhibition using a membrane-impermeant sulfonamide inhibitor in neuronal models of brain ischemia. The treatments exerted neuroprotective effects on neurons from Car9 knockout mice. Moreover, administration of the sulfonamide inhibitor to rats subjected to transient middle cerebral artery occlusion decreased infarct volumes and improved neurological deficits. Our results support the involvement of carbonic anhydrase IX in postischemic damage and pave the way for possible pharmacological interventions with selective inhibitors in the management of brain ischemia.

Novel N-(3-(1-(4-sulfamoylphenyl)triazol-4-yl)phenyl)benzamide Derivatives as Potent Carbonic Anhydrase Inhibitors with Broad-Spectrum Anticancer Activity: Leveraging Tail and Dual-Tail Approaches

Carbonic anhydrases (CAs) IX and XII are crucial for the survival and metastasis of solid tumors under hypoxic conditions. We designed compounds 7a-s, integrating triazole and benzenesulfonamide scaffolds known for inhibiting tumor-associated CAs IX/XII. Initial synthesis included compounds 7a-e, followed by diversification with small hydrophobic groups (7f-m) and hydrophilic heterocyclic secondary amines (7n-s). Compounds were evaluated against CA II, IX, and XII to assess activity and selectivity. Chlorinated derivative 7l exhibited the highest efficacy against CA IX (KI = 0.317 μM) and ditrifluoromethylated 7j against CA XII (KI = 0.081 μM). Subsequent testing on 60 cancer cell lines at 10 μM revealed promising anticancer activity, especially for dimethylated derivative 7h (CA IX, KI = 1.324 μM; CA XII, KI = 0.435 μM), with GI50 values ranging from 0.361 to 9.21 μM. Molecular docking analyses elucidated binding mechanisms, highlighting potential inhibitory actions of compound 7h on CAs IX and XII.

Synthetic strategies and medicinal chemistry perspectives of dual acting carbonic anhydrase modulators with monoamine oxidase and cholinesterase inhibitors

Multi-target drug design (MTDD) represents the paradigm shift in pharmaceutical research, moving beyond the conventional one-drug-one-target approach to address the complexity of multifactorial diseases. This strategy aims to develop single therapeutic candidates that can simultaneously modulate multiple biological targets, offering more comprehensive disease management and reducing the likelihood of drug resistance. In this article, we highlighted the design, synthesis, and structure-activity relationships (SARs) of various dual acting inhibitors involved in treatment of neurodegenerative diseases. Dual acting inhibitors targeting carbonic anhydrases (CAs), monoamine oxidases (MAOs), and cholinesterases (ChEs) have emerged as promising therapeutic agents due to their potential in treating complex neurodegenerative and psychiatric disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). By integrating CA inhibitors with MAO and ChE inhibition, researchers aim to address both the neuroprotective and symptomatic aspects of these disorders. The review also discusses key SAR studies that have guided the optimization of dual inhibitors, focusing on achieving selectivity and potency while minimizing off-target effects. From a medicinal chemistry perspective, the dual inhibition approach offers advantages such as improved efficacy, reduced polypharmacy, and better management of disease progression. However, challenges remain, including maintaining selectivity for target isoforms and overcoming pharmacokinetic limitations. Overall, the development of dual-acting CA-MAO-ChE inhibitors represents a compelling avenue in drug discovery, with the potential to significantly impact the treatment of neurodegenerative diseases.

Predicting Carbonic Anhydrase Binding Affinity: Insights from QM Cluster Models

A systematic series of QM cluster models has been developed to predict the trend in the carbonic anhydrase binding affinity of a structurally diverse dataset of ligands. Reference DLPNO-CCSD(T)/CBS binding energies were generated for a cluster model and used to evaluate the performance of contemporary density functional theory methods, including Grimme's "3c" DFT composite methods (r2SCAN-3c and ωB97X-3c). It is demonstrated that when validated QM methods are used, the predictive power of the cluster models improves systematically with the size of the cluster models. This provided valuable insights into the key interactions that need to be modeled quantum mechanically and could inform how the QM region should be defined in hybrid quantum mechanics/molecular mechanics (QM/MM) models. The use of r2SCAN-3c on the largest cluster model composed of 16 residues appears to be an economical approach to predicting binding trends compared with using more robust DFT methods such as ωB97M-V and provides a significant improvement compared with docking.

Mass Transfer-Reaction Modeling of CO2 Capture Mediated by Immobilized Carbonic Anhydrase Enzyme on Multiscale Supporting Structures

Immobilized carbonic anhydrase (CA) enzyme enhances CO2 absorption in potassium carbonate (PC) solutions, offering an attractive alternative to amine-based processes for postcombustion carbon capture. In this work, the cross-scale models of mass transfer coupled with absorption reactions were developed to evaluate the structural impacts of different enzyme immobilization supporting materials, including nonporous nanoparticle carriers (nano scale), porous microparticle carriers (micro scale), and fixed packing structures (macro scale), on the rate enhancement effect of the immobilized CA. Increasing enzyme activity was demonstrated to be an effective approach to promoting the CO2 absorption rate; however, there was an upper limit due to the limitation of CO2 diffusion in the liquid phase, either adjacent to the gas-liquid interface or the liquid-solid interface. The size of particle carriers is another critical factor affecting the CO2 absorption rate. Only nanoscale particle carriers could directly enter the region within the liquid film of mass transfer, thus providing effective enzymatic enhancement. When the particle size was reduced to below 0.35 μm, the PC promoted with the immobilized CA outperformed the benchmark monoethanolamine solution. The solid-side mass transfer resistance became dominant as the particle size decreased. Modeling results also showed that using stagnant packing materials in a fixed bed as a supporting structure for CA immobilization would be impractical for accelerating CO2 absorption.

Structural information in therapeutic peptides: Emerging applications in biomedicine

Peptides are attracting a growing interest as therapeutic agents. This trend stems from their cost-effectiveness and reduced immunogenicity, compared to antibodies or recombinant proteins, but also from their ability to dock and interfere with large protein-protein interaction surfaces, and their higher specificity and better biocompatibility relative to organic molecules. Many tools have been developed to understand, predict, and engineer peptide function. However, most state-of-the-art approaches treat peptides only as linear entities and disregard their structural arrangement. Yet, structural details are critical for peptide properties such as solubility, stability, or binding affinities. Recent advances in peptide structure prediction have successfully addressed the scarcity of confidently determined peptide structures. This review will explore different therapeutic and biotechnological applications of peptides and their assemblies, emphasizing the importance of integrating structural information to advance these endeavors effectively.

Carbonic anhydrase 4 disruption and pharmacological inhibition reduce synaptic and behavioral adaptations following oxycodone withdrawal

The ongoing opioid crisis underscores the need for innovative treatments targeting neurobiological mechanisms underlying opioid-seeking behaviors and relapse. Here we explored the role of carbonic anhydrase 4 (CA4) in modulating synaptic adaptations to oxycodone withdrawal in mice. We disrupted CA4 genetically and inhibited it pharmacologically with acetazolamide (AZD), a carbonic anhydrase inhibitor used clinically. We found that oxycodone withdrawal increased AMPAR/NMDAR ratio and synaptic recruitment of calcium-permeable AMPARs in nucleus accumbens core (NAcC) medium spiny neurons (MSNs). Synaptic changes required an extended period of abstinence, generalized across opioids including morphine and heroin, were specific to D1 dopamine receptor-expressing MSNs, and were prevented by CA4 disruption. AZD administration in vitro and in vivo reversed the synaptic alterations, and effects of AZD depended on CA4 and acid sensing ion channel 1A (ASIC1A). Interestingly, abstinence from oxycodone did not affect dendritic spine density in NAcC MSNs, in contrast to previously observed effects of abstinence from cocaine. Finally, in an oxycodone self-administration paradigm, CA4 disruption and AZD reduced drug-seeking behaviors following 30 days of forced abstinence. Together, these findings identify a critical role for CA4 in synaptic adaptations in opioid withdrawn mice and drug-seeking behavior. Moreover, they suggest pharmacological inhibitors of CA4 may hold therapeutic potential for reducing opioid-seeking and relapse in opioid use disorder.

A photo-triggered dual-gas donor of nitric oxide and hydrogen sulfide with fluorescence for real-time monitoring of its release

Multi-gaseous signal molecules play a significant role in regulating various physiological and pathological processes. Therefore, studying the synergistic effects of multi-gas donors on biological systems is essential. However, different types of gas donors vary significantly in terms of gas release, including location, dose, and flux. These variations can have a dramatic impact on the biological effects of the gases and require further analysis for confirmation. Thus, a controllable dual-gas donor that enables self-reporting would be valuable for studying the biological effects of two species of gaseous signal molecules. Herein, we present a novel photo-triggered donor, NHD545, which releases nitric oxide and hydrogen sulfide simultaneously. Furthermore, the dual-gas release from this donor is accompanied by turn-on fluorescence, which could be utilized to monitor the NO and H2S release by microscopy. With NHD545, it is convenient to investigate the synergistic effect of dual-gas bioavailability in vitro.

Emerging trends in long-acting sustained drug delivery for glaucoma management

Glaucoma is an optic neuropathy in which progressive degeneration of retinal ganglion cells and the optic nerve leads to irreversible visual loss. Glaucoma is one of the leading causes of blindness. The pathogenesis of glaucoma is determined by different pathogenetic mechanisms, including increased intraocular pressure, mechanical stress, excitotoxicity, resistance to aqueous drainage and oxidative stress. Topical formulations are often used in glaucoma treatment, whereas surgical measures are used in acute glaucoma cases. For most patients, long-term glaucoma treatments are given. Poor patient compliance and low bioavailability are often associated with topical therapy, which suggests that sustained-release, long-acting drug delivery systems could be beneficial in managing glaucoma. This review summarizes the eye's physiology, the pathogenesis of glaucoma, current treatments, including both pharmacological and nonpharmacological interventions, and recent advances in long-acting drug delivery systems for the treatment of glaucoma.

Tetrazole Is a Novel Zinc Binder Chemotype for Carbonic Anhydrase Inhibition

The tetrazole group is here proposed as a zinc-binding warhead for the inhibition of the metalloenzyme carbonic anhydrases. A set of synthesized derivatives incorporating the tetrazole moiety were evaluated as inhibitors against a panel of human isoforms, exhibiting K I values spanning between the submicromolar and low-to-medium micromolar ranges (0.62-19.6 μM). X-ray crystallographic studies were conducted to gain insights into their modes of binding to the target enzyme. These findings mark a significant advancement in the search for inhibitory chemotypes other than classical sulfonamides.

Multiple Binding Modes of Inhibitors to Human Carbonic Anhydrases: An Update on the Design of Isoform-Specific Modulators of Activity

Human carbonic anhydrases (hCAs) are widespread zinc enzymes that catalyze the hydration of CO2 to bicarbonate and a proton. Currently, 15 isoforms have been identified, of which only 12 are catalytically active. Given their involvement in numerous physiological and pathological processes, hCAs are recognized therapeutic targets for the development of inhibitors with biomedical applications. However, despite massive development efforts, very few of the presently available hCA inhibitors show selectivity for a specific isoform. X-ray crystallography is a very useful tool for the rational drug design of enzyme inhibitors. In 2012 we published in Chemical Reviews a highly cited review on hCA family (Alterio, V. et al. Chem Rev. 2012, 112, 4421-4468), analyzing about 300 crystallographic structures of hCA/inhibitor complexes and describing the different CA inhibition mechanisms existing up to that date. However, in the period 2012-2023, almost 700 new hCA/inhibitor complex structures have been deposited in the PDB and a large number of new inhibitor classes have been discovered. Based on these considerations, the aim of this Review is to give a comprehensive update of the structural aspects of hCA/inhibitor interactions covering the period 2012-2023 and to recapitulate how this information can be used for the rational design of more selective versions of such inhibitors.

Multi- and polypharmacology of carbonic anhydrase inhibitors

Eight genetically distinct families of the enzyme carbonic anhydrase (CA, EC 4.2.1.1) have been described in organisms overall in the phylogenetic tree. They catalyze the hydration of CO2 to bicarbonate and protons and are involved in pH regulation, chemosensing, and metabolism. The 15 α-CA isoforms present in humans are pharmacological drug targets known for decades, their inhibitors being used as diuretics, antiglaucoma, antiepileptic, or antiobesity drugs, as well as for the management of acute mountain sickness, idiopathic intracranial hypertension, and recently, as antitumor theragnostic agents. Other potential applications include the use of CA inhibitors (CAIs) in inflammatory conditions, cerebral ischemia, neuropathic pain, or Alzheimer/Parkinson disease management. CAs from pathogenic bacteria, fungi, protozoans, and nematodes have started to be considered as drug targets in recent years, with notable advances being registered. CAIs have a complex multipharmacology probably unique to this enzyme, which has been exploited intensely but may lead to other relevant applications in the future due to the emergence of drug design approaches that afforded highly isoform-selective compounds for most α-CAs known to date. They belong to a multitude of chemical classes (sulfonamides and isosteres, [iso]coumarins and related compounds, mono- and dithiocarbamates, selenols, ninhydrines, boronic acids, benzoxaboroles, etc). The polypharmacology of CAIs will also be discussed because drugs originally discovered for the treatment of non-CA related conditions (topiramate, zonisamide, celecoxib, pazopanib, thiazide, and high-ceiling diuretics) show effective inhibition against many CAs, which led to their repurposing for diverse pharmacological applications. SIGNIFICANCE STATEMENT: CAIs have multiple pharmacologic applications, such as diuretics, antiglaucoma, antiepileptic, antiobesity, antiacute mountain sickness, anti-idiopathic intracranial hypertension, and antitumor drugs. Their use in inflammatory conditions, cerebral ischemia, neuropathic pain, or neurodegenerations has started to be investigated recently. Parasite carbonic anhydrases are also drug targets for anti-infectives with novel mechanisms of action that can bypass drug resistance to commonly used agents. Drugs discovered for the management of other conditions that effectively inhibit these enzymes exert interesting polypharmacologic effects.

Unprecedented carbonic anhydrase inhibition mechanism: Targeting histidine 64 side chain through a halogen bond

2,2'-Thio-bis(4,6-dichlorophenol), namely bithionol, is a small molecule endowed with a multifaceted bioactivity. Its peculiar polychlorinated phenolic structure makes it a suitable candidate to explore its potentialities in establishing interaction patterns with enzymes of MedChem interest, such as the human carbonic anhydrase (hCA) metalloenzymes. Herein, bithionol was tested on a panel of specific hCAs through the stopped-flow technique, showing a promising micromolar inhibitory activity for the hCA II isoform. X-ray crystallographic studies revealed an unprecedented halogen-bond interaction between one chlorine of bithionol and the N3(ε) atom of the hCA II catalytically active histidine residue, His64. Then, quantum mechanics calculations based on the fragment molecular orbital method allowed us to estimate the strength of this bond (~2.9 kcal/mol) and highlighted the contribution of a rich hydrophobic interaction network within the isoenzyme. Interestingly, the compound inactivity against the hCA III isoform, characterized by His64Lys and Leu198Phe mutations, supported the key role played by halogen bonding in the enzyme affinity. This finding might pave the way for the development of a new class of hCA inhibitors characterized by such chemical features, with the halogen bond being a key ligand-receptor interaction.

New 7-hydroxycoumarin acetamide derivatives as human carbonic anhydrase IX and XII inhibitors: Design, synthesis, biological evaluation and molecular docking studies

Carbonic anhydrases (CAs) are crucial in regulating various physiological processes in the body. The overexpression of isoforms human carbonic anhydrases (hCA) IX and hCA XII is linked to tumour progression. The selective inhibition of CA IX and CA XII isoforms can result in the development of better cancer treatment strategies. The tail approach based on coumarin derivatives was known for selective inhibition of isoforms IX and XII. This study explores the potential of coumarin derivatives (7a-k, 8a-s and 9a-g) as selective hCA IX and hCA XII inhibitors. The synthesised derivatives exhibited potent and selective inhibition towards hCA IX and XII, with Ki values in the range of 0.58‒3.33 µM and 0.48‒2.59 µM, respectively. The oxime ether derivative 7d was found to be the most potent one against hCA IX, with a Ki value of 0.58 µM, and phenyl hydrazine derivative 8a, with a Ki value of 0.48 µM against hCA XII, was the most potent one among the synthesised molecules. The potent isoform-specific carbonic anhydrase IX and XII inhibition suggests that 7d and 8a can be taken further towards the development of potent anticancer agents.

Design, Synthesis, and In Vitro Evaluation of Aromatic Sulfonamides as Human Carbonic Anhydrase I, II, IX, and XII Inhibitors and Their Antioxidant Activity

This study is focused on the design, synthesis, and evaluation of some sulfonamide derivatives for their inhibitory effects on human carbonic anhydrase (hCA) enzymes I, II, IX, and XII as well as for their antioxidant activity. The purity of the synthesized molecules was confirmed by the HPLC purity analysis and was found in the range of 93%-100%. The inhibition constant (Ki) against hCA I ranged from 0.75 nM to 1972 nM. The sulfonamides inhibited isoform hCA II significantly, with a Ki ranging from 0.09 to 56 nM. Similarly, the inhibitory effects on hCA IX and XII were found with Ki spanning from 27.8 to 2099 nM and 9.43 to 509 nM, respectively. Most of the synthesized compounds showed significant inhibition in comparison to standard drugs such as acetazolamide, ethoxzolamide, zonisamide, methazolamide, dorzolamide, and SLC-0111. Antioxidant activity was assessed using the DPPH assay, with compound 13 showing better antioxidant activity with an IC50 of 54.8 µg/mL, as compared to the standard ascorbic acid (IC50 64.7 µg/mL). The molecular docking studies provided insights into the binding modes of these compounds. The in silico physicochemical properties, pharmacokinetic/ADME, and toxicity properties evaluations confirmed favorable drug-likeness properties, complying with Lipinski's rule. These findings underscore the therapeutic potential of these compounds for the treatment of retinal/cerebral edema, glaucoma, edema, epilepsy management, high-altitude sickness, and cancer.

A Computational Approach Using α-Carbonic Anhydrase to Find Anti-Trypanosoma cruzi Agents

BACKGROUND

Chagas disease has an ineffective drug treatment despite efforts made over the last four decades. The carbonic anhydrase of Trypanosoma cruzi (α-TcCA) has emerged as an interesting target for the design of new antiparasitic compounds due to its crucial role in parasite processes.

OBJECTIVE

The aim in this study was identify potential α-TcCA inhibitors with trypanocidal activity.

METHODS

A maximum common substructure (MCS) and molecular docking were used to carried out a ligand- and structure-based virtual screening of ZINC20 and MolPort databases. The compounds selected were evaluated in an in vitro model against the NINOA strain of Trypanosoma cruzi, and cytotoxicity was determined in a murine model of macrophage cells J774.2.

RESULTS

Five sulfonamide derivatives (C7, C9, C14, C19, and C21) had the highest docking scores (-6.94 to -8.31 kcal/mol). They showed key residue interactions on the active site of the α-TcCA and good biopharmaceutical and pharmacokinetic properties. C7, C9, and C21 had half-maximal inhibitory concentration (IC50) values of 26, 61.6, and 49 μM, respectively, against NINOA strain epimastigotes of Trypanosoma cruzi.

CONCLUSION

Compounds C7, C9, and C21 showed trypanocidal activity; therefore, these results encourage the development of new trypanocidal agents based in their scaffold.

The carbonic anhydrase enzymes as new targets for the management of neglected tropical diseases

Diseases caused by protozoan parasites represent a huge challenge to global health care, due to the lack of selective and efficient treatments for the management and spreading of such complex pathologies. The protozoans Trypanosoma cruzi (T. cruzi) and Leishmania spp. are the etiological agents of the so-called neglected tropical diseases (NTDs), that is, Chagas disease (CD) and leishmaniasis, respectively. In such a context, the metalloenzymes carbonic anhydrases (CAs; EC 4.2.1.1) emerged as potential protozoan druggable enzymes, being involved in the parasites' life cycle. Several studies suggested the relevance of the protozoan-expressed CAs as future candidates for the management of NTDs.

Lactonase activity of α-carbonic anhydrases allows identification of novel inhibitors

Lactones, a diverse and abundant class of molecules found in nature, exhibit a wide range of bioactivities, including anti-inflammatory, anticancer, and antibacterial effects. Among them, acyl homoserine lactones (AHSLs) play a crucial role in quorum sensing, influencing bacterial pathogenicity and biofilm formation in Gram-negative bacteria. Paraoxonases (PONs), calcium-containing enzymes known for their lactonase activity, have been shown to hydrolyze AHSLs and reduce the biofilm formation of several pathogenic bacteria. In this study, we explored the potential lactonase activity of a class of zinc(II) enzymes, the carbonic anhydrases (CAs), aiming to uncover new insights into their catalytic versatility. Using LC-MS and MS/MS analyses, we investigated the lactonase activity of CAs and assessed several lactones through a stopped-flow kinetic assay as substrates/inhibitors. Our findings reveal that lactones are novel "prodrug" inhibitors of CAs, with lactones DHC and 6 showing the most promising inhibition constants (KIs) in the low micromolar range against both human and bacterial isozymes.

Discovery of the First-in-Class Dual TSPO/Carbonic Anhydrase Modulators with Promising Neurotrophic Activity

In searching for putative new therapeutic strategies to treat neurodegenerative diseases, the mitochondrial 18 kDa translocator protein (TSPO) and cerebral isoforms of carbonic anhydrase (CA) were exploited as potential targets. Based on the structures of a class of highly affine and selective TSPO ligands and a class of CA activators, both developed by us in recent years, a small library of 2-phenylindole-based dual TSPO/CA modulators was developed, able to bind TSPO and activate CA VII in the low micromolar/submicromolar range. The interaction with the two targets was corroborated by computational studies. Biological investigation on human microglia C20 cells identified derivative 3 as a promising lead compound worthy of future optimization due to its (i) lack of cytotoxicity, (ii) ability to stimulate TSPO steroidogenic function and activate CA VII, and (iii) ability to effectively upregulate gene expression of the brain-derived neurotrophic factor.

Current Status and Perspectives of Novel Radiopharmaceuticals with Heterologous Dual-targeted Functions: 2013-2023

Radiotracers provide molecular- and cellular-level information in a noninvasive manner and have become important tools for precision medicine. In particular, the successful clinical application of radioligand therapeutic (RLT) has further strengthened the role of nuclear medicine in clinical treatment. The complicated microenvironment of the lesion has rendered traditional single-targeted radiopharmaceuticals incapable of fully meeting the requirements. The design and development of dual-targeted and multitargeted radiopharmaceuticals have rapidly emerged. In recent years, significant progress has been made in the development of heterologous dual-targeted radiopharmaceuticals. This perspective aims to provide a comprehensive overview of the recent progress in these heterologous dual-targeted radiopharmaceuticals, with a special focus on the design of ligand structures, pharmacological properties, and preclinical and clinical evaluation. Furthermore, future directions are discussed from this perspective.

Exploring the Pharmacological Potential of Carrageenan Disaccharides as Antitumor Agents: An In Silico Approach

Carrageenans have demonstrated enhanced antitumor activity upon depolymerization into disaccharides. However, the pharmacological viability of these disaccharides and their mechanisms of antitumor action remains to be fully elucidated. This study aimed to employ computational tools to investigate the pharmacological properties and molecular targets pertinent to cancer of the disaccharides derived from the primary carrageenans. Analyses of pharmacological properties predicted by the pkCSM and SwissADME servers indicated that the disaccharides possess a favorable pharmacokinetic profile, although they encounter permeability challenges primarily due to their high polarity and low lipophilicity. Target prediction using SwissTarget and PPB2 identified five carbonic anhydrases, which are also targets of oncology drugs, as common targets for the disaccharides. Molecular docking performed with AutoDock Vina revealed that the binding energies of the disaccharides with carbonic anhydrases were comparable to or greater than those of existing drugs that target these lyases. Notably, six of the complexes formed exhibited interactions between the disaccharides and the zinc cofactor, which represents a primary mechanism of inhibition for these targets. Furthermore, molecular dynamics simulations conducted using GROMACS demonstrated a stable interaction between the disaccharides and carbonic anhydrases. These findings offer new insights into the pharmacological properties and mechanisms of action of carrageenan-derived disaccharides, highlighting their potential for further exploration in clinical trials and experimental studies.

The Antiepileptic Drug Levetiracetam Inhibits Carbonic Anhydrase: In Vitro and In Silico Studies on Catalytically Active Human Isoforms

Several antiepileptic drugs (AEDs) have been found to inhibit human carbonic anhydrases (hCAs), paving the way for repurposing AEDs for the treatment of various diseases, including cancer. Here, the hCAs inhibitory effects of levetiracetam, a highly prescribed AED that does not bear a common zinc-binding group, were investigated in vitro and in silico. Levetiracetam inhibited all tested hCAs, although with a specific profile compared to the reference acetazolamide, with remarkable efficacy against tumor-associated hCA IX and XII. Molecular docking and dynamics (MD) simulations emphasized H-bonding to the Zn(II)-coordinated water as a major anchor point for hCAs, as well as a persistent interaction within the catalytic site of hCA isoforms IX and XII compared to II, which correlates with experimental data. Our results may explain why levetiracetam is also clinically effective as an antitumor agent in patients developing epilepsy as a consequence of brain tumors.

Sulphonyl thiourea compounds containing pyrimidine as dual inhibitors of I, II, IX, and XII carbonic anhydrases and cancer cell lines: synthesis, characterization and in silico studies

Some novel sulphonyl thiourea derivatives (7a-m) containing 4,6-diarylpyrimidine rings were designed and synthesized using a one-pot procedure. These compounds exhibited remarkable dual inhibitory activity against human carbonic anhydrase hCA I, hCA II, hCA IX, and XII isoenzymes and some cancer cell lines. Among them, some thioureas had significantly more potent inhibitory activities in the order of 7l > 7c > 7f (against the hCA I isoform), 7f > 7b > 7c (against the hCA II isoform), 7c > 7g > 7a > 7b (against the hCA IX isoform), and 7d > 7c > 7g > 7f (against the hCA XII isoform). The obtained inhibitory activity data against the hCA IX and XII isoforms showed that compound 7c was the most potent inhibitor in this sulphonyl thiourea series against enzyme hCA IX, with K I = 125.1 ± 12.4 nM, while compound 7d was the most potent inhibitor against enzyme hCA XII, with K I = 111.0 ± 12.3 nM. Compound 7c exhibited strong inhibitory activity among all four tested hCA enzymes, while thiourea 7f was a potent inhibitor for enzymes hCA I, II and XII. All these compounds demonstrated non-competitive inhibition of both enzymes. Some selected potential inhibitory compounds, including 7c, 7d, and 7g, exhibited remarkable cytotoxic activity against human cancer cell lines, including human breast adenocarcinoma (MCF-7), human liver adenocarcinoma (HepG2), human cervical epithelial carcinoma (HeLa), and human lung adenocarcinoma cells (A549). These compounds exhibited low cytotoxicity in the WI-38 cell line. The compounds 7c and 7d were the most potent inhibitors against tumour-associated hCA IX and hCA XII isoenzymes. Furthermore, these compounds exhibited remarkable inhibition against some cancer cell lines, such as MCF-7, HepG2, HeLa, and A549. They 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 7c and 7d were the most promising derivatives in this series owing to their significant effects on the studied hCA IX and hCA XII isoenzymes, respectively. The results showed that the sulphonyl thiourea moiety was deeply accommodated in the active site and interacted with zinc ions in the receptors.

Carbonic anhydrase inhibitors prevent presymptomatic capillary flow disturbances in a model of cerebral amyloidosis

INTRODUCTION

Disturbances in microvascular flow dynamics are hypothesized to precede the symptomatic phase of Alzheimer's disease (AD). However, evidence in presymptomatic AD remains elusive, underscoring the need for therapies targeting these early vascular changes.

METHODS

We employed a multimodal approach, combining in vivo optical imaging, molecular techniques, and ex vivo MRI, to investigate early capillary dysfunction in Tg-SwDI mice without memory impairment. We also assessed the efficacy of carbonic anhydrase inhibitors (CAIs) in preventing capillary flow disturbances.

RESULTS

Our study revealed capillary flow disturbances associated with alterations in capillary morphology, adhesion molecule expression, and Amyloid-β (Aβ) load in 9-10-month-old Tg-SwDI mice without memory impairment. CAI treatment ameliorated these capillary flow disturbances, enhanced oxygen availability, and reduced Aβ load.

DISCUSSION

These findings underscore the importance of capillary flow disturbances as early biomarkers in presymptomatic AD and highlight the potential of CAIs for preserving vascular integrity in the early stages of AD.

CRISPRi/a screens in human iPSC-cardiomyocytes identify glycolytic activation as a druggable target for doxorubicin-induced cardiotoxicity

Doxorubicin is limited in its therapeutic utility due to its life-threatening cardiovascular side effects. Here, we present an integrated drug discovery pipeline combining human induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iCMs), CRISPR interference and activation (CRISPRi/a) bidirectional pooled screens, and a small-molecule screening to identify therapeutic targets mitigating doxorubicin-induced cardiotoxicity (DIC) without compromising its oncological effects. The screens revealed several previously unreported candidate genes contributing to DIC, including carbonic anhydrase 12 (CA12). Genetic inhibition of CA12 protected iCMs against DIC by improving cell survival, sarcomere structural integrity, contractile function, and calcium handling. Indisulam, a CA12 antagonist, can effectively attenuate DIC in iCMs, engineered heart tissue, and animal models. Mechanistically, doxorubicin-induced CA12 potentiated a glycolytic activation in cardiomyocytes, contributing to DIC by interfering with cellular metabolism and functions. Collectively, our study provides a roadmap for future drug discovery efforts, potentially leading to more targeted therapies with minimal off-target toxicity.

Serum proteome profiling of plateau acclimatization in men using Olink proteomics approach

Plateau acclimatization involves adaptive changes in the body's neurohumoral regulation and metabolic processes due to hypoxic conditions at high altitudes. This study utilizes Olink targeted proteomics to analyze serum protein expression differences in Han Chinese individuals acclimatized for 6 months-1 year at 4500 and 5300 m altitudes, compared to those residing at sea level. The objective is to elucidate the proteins' roles in tissue and cellular adaptation to hypoxia. We identified 54 metabolism-related differentially expressed proteins (DEPs) in the serum of the high-altitude group versus the sea-level group, comprising 20 significantly upregulated and 34 downregulated proteins. Notably, 2 proteins were upregulated and 11 downregulated at both 4500 and 5300 m altitudes. The top three protein correlations among DEPs included CRKL with CA13, RNASE3 with NADK, and NADK with APEX1, alongside APLP1 with CTSH, CTSH with SOST, and CTSH with NT-proBNP in inverse correlations. KEGG enrichment analysis indicated significant DEP involvement in various metabolic pathways, particularly those associated with hypoxic cellular metabolism like glycolysis/gluconeogenesis and the HIF-1 signaling pathway. Correlation with clinical phenotypes showed positive associations of SOST, RNASE3, CA13, NADK, and CRKL with SaO2 and negative correlations with Hemoglobin and Hematocrit; ALDH1A1 positively correlated with Triglyceride; and SDC4 inversely correlated with Uric acid levels. This study provides insights into specific DEPs linked to metabolic adaptations in high-altitude acclimatized individuals, offering a foundation for understanding acclimatization mechanisms and potential therapeutic targets.

Acetazolamide and human carbonic anhydrases: retrospect, review and discussion of an intimate relationship

Acetazolamide (AZM) is a strong pharmacological sulphonamide-type (R-SO2-NH2, pKa 7.2) inhibitor of the activity of several carbonic anhydrase (CA) isoforms, notably of renal CA II (Ki, 12 nM) and CA IV (Ki, 74 nM). AZM is clinically used for about eighty years in various diseases including epilepsy and glaucoma. Pharmacological AZM increases temporarily the urinary excretion of bicarbonate (HCO3-) and sodium ions (Na+) and sustainably the urinary pH. AZM is excreted almost unchanged over several hours at high rates in the urine. Closely parallel concentrations of circulating and excretory AZM are observed upon administration of therapeutical doses of AZM. In a proof-of-principle study, we investigated the effects of the ingestion of a 250-mg AZM-containing tablet by a healthy volunteer on the urinary excretion of organic and inorganic substances over 5 h (range, 0, 0.5, 1, 1.5, 2, 3, 4, 5 h). Measured analytes included: AZM, amino acids and their metabolites such as guanidinoacetate, i.e. the precursor of creatine, of asymmetrically (ADMA) and symmetrically (SDMA) dimethylated arginine, nitrite (O = N-O-, pKa 3.4) and nitrate (O2N-O-, pKa -1.37), the major metabolites of nitric oxide (NO), the C-H acidic malondialdehyde (MDA; (CHO)2CH2, pKa 4.5), and creatinine for correction of analytes excretion. All analytes were measured by validated isotopologues using gas chromatography-mass spectrometry (GC-MS) methods. AZM excretion in the urine reached its maximum value after 2 h and was fairly stable for the next 3 h. Time series analysis by the ARIMA method was performed. AZM ingestion increased temporarily the urinary excretion of the amino acids Leu + Ile, nitrite and nitrate, decreased temporarily the urinary excretion of other amino acids. AZM decreased sustainably the urinary excretion of MDA, a biomarker of oxidative stress (i.e. lipid peroxidation). Whether this decrease is due to inhibition of the excretion of MDA or attenuation of oxidative stress by AZM is unknown. The acute and chronic effects of AZM on the urinary excretion of electrolytes and physiological substances reported in the literature are discussed in depth in the light of its extraordinary pharmacokinetics and pharmacodynamics. Tolerance development/drug resistance to AZM in chronic use and potential mechanisms are also addressed.

Imbalanced and Unchecked: The Role of Metal Dyshomeostasis in Driving COPD Progression

Chronic obstructive pulmonary disease (COPD) is a chronic respiratory condition characterized by persistent inflammation and oxidative stress, which ultimately leads to progressive restriction of airflow. Extensive research findings have cogently suggested that the dysregulation of essential transition metal ions, notably iron, copper, and zinc, stands as a critical nexus in the perpetuation of inflammatory processes and oxidative damage within the lungs of COPD patients. Unraveling the intricate interplay between metal homeostasis, oxidative stress, and inflammatory signaling is of paramount importance in unraveling the intricacies of COPD pathogenesis. This comprehensive review aims to examine the current literature on the sources, regulation, and mechanisms by which metal dyshomeostasis contributes to COPD progression. We specifically focus on iron, copper, and zinc, given their well-characterized roles in orchestrating cytokine production, immune cell function, antioxidant depletion, and matrix remodeling. Despite the limited number of clinical trials investigating metal modulation in COPD, the advent of emerging methodologies tailored to monitor metal fluxes and gauge responses to chelation and supplementation hold great promise in unlocking the potential of metal-based interventions. We conclude that targeted restoration of metal homeostasis represents a promising frontier for ameliorating pathological processes driving COPD progression.

Bee venom and melittin: Potent key enzyme inhibitors with promising therapeutic potential

Bee venom (BV) is a versatile product with extensive applications, boasting antibacterial and anticancer properties. Within this study, we focused on isolating melittin (Mel) from Apis mellifera L. venom and exploring the influence of both BV and Mel on specific enzymes, namely carbonic anhydrase (CA) I, CA II, CA IX, glutathione reductase (GR), acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and neuraminidase (NA). The rationale for selecting these enzymes is that their inhibitors have a particular interest in medicinal chemistry in the treatment of several diseases. BV was obtained using a poison collection apparatus, and Mel was isolated by means of High-Performance Liquid Chromatography (HPLC). All enzymes, except for CA I and CA II, were commercially sourced and of high purity, and the enzyme assays were carried out spectrophotometrically. Our findings showed that BV inhibited the enzymes with IC50 values of 0.583-3.32 ng/mL, and Mel showed an inhibition range of 0.528-3.2 ng/mL. These results underscore the potential therapeutic promise of BV and Mel as robust enzyme inhibitors, offering prospects for addressing diverse health conditions.