Activation of carbonic anhydrase isoforms involved in modulation of emotional memory and cognitive disorders with histamine agonists, antagonists and derivatives

Drug interactions of carbonic anhydrase inhibitors and activators

INTRODUCTION

Carbonic anhydrases (CAs, EC 4.2.1.1) have been established drug targets for decades, with their inhibitors and activators possessing relevant pharmacological activity and applications in various fields. At least 11 sulfonamides/sulfamates are clinically used as diuretics, antiglaucoma, antiepileptic, or antiobesity agents and one derivative, SLC-0111, is in clinical trials as antitumor/antimetastatic agent. The activators were less investigated with no clinically used agent.

AREAS COVERED

Drug interactions between CA inhibitors/activators and various other agents are reviewed in publications from the period March 2020 - January 2024.

EXPERT OPINION

Drug interactions involving these agents revealed several interesting findings. Acetazolamide plus loop diuretics is highy effective in acute decompensated heart failure, whereas ocular diseases such as X-linked retinoschisis and macular edema were treated by acetazolamide plus bevacizumab or topical NSAIDs. Potent anti-infective effects of acetazolamide and other CAIs, alone or in combination with other agents were demonstrated for the management of Neisseria gonorrhoea, vancomycin resistant enterococci, Acanthamoeba castellanii, Trichinella spiralis, and Cryptococcus neoformans infections. Topiramate, in combination with phentermine is incresingly used for the management of obesity, whereas zonisamide plus levodopa is highly effective for Parkinson's disease. Acetazolamide, methazolamide, ethoxzolamide, and SLC-0111 showed synergistic antitumor/antimetastatic action in combination with many other antitumor drugs.

S-9-PAHSA's neuroprotective effect mediated by CAIII suppresses apoptosis and oxidative stress in a mouse model of type 2 diabetes

BACKGROUND

With the rapidly increasing prevalence of metabolic diseases such as type 2 diabetes mellitus (T2DM), neuronal complications associated with these diseases have resulted in significant burdens on healthcare systems. Meanwhile, effective therapies have remained insufficient. A novel fatty acid called S-9-PAHSA has been reported to provide metabolic benefits in T2DM by regulating glucose metabolism. However, whether S-9-PAHSA has a neuroprotective effect in mouse models of T2DM remains unclear.

METHODS

This in vivo study in mice fed a high-fat diet (HFD) for 5 months used fasting blood glucose, glucose tolerance, and insulin tolerance tests to examine the effect of S-9-PAHSA on glucose metabolism. The Morris water maze test was also used to assess the impact of S-9-PAHSA on cognition in the mice, while the neuroprotective effect of S-9-PAHSA was evaluated by measuring the expression of proteins related to apoptosis and oxidative stress. In addition, an in vitro study in PC12 cells assessed apoptosis, oxidative stress, and mitochondrial membrane potential with or without CAIII knockdown to determine the role of CAIII in the neuroprotective effect of S-9-PAHSA.

RESULTS

S-9-PAHSA reduced fasting blood glucose levels significantly, increased insulin sensitivity in the HFD mice and also suppressed apoptosis and oxidative stress in the cortex of the mice and PC12 cells in a diabetic setting. By suppressing oxidative stress and apoptosis, S-9-PAHSA protected both neuronal cells and microvascular endothelial cells in in vivo and in vitro diabetic environments. Interestingly, this protective effect of S-9-PAHSA was reduced significantly when CAIII was knocked down in the PC12 cells, suggesting that CAIII has a major role in the neuroprotective effect of S-9-PAHSA. However, overexpression of CAIII did not significantly enhance the protective effect of S-9-PAHSA.

CONCLUSION

S-9-PAHSA mediated by CAIII has the potential to exert a neuroprotective effect by suppressing apoptosis and oxidative stress in neuronal cells exposed to diabetic conditions. Furthermore, S-9-PAHSA has the capability to reduce fasting blood glucose and LDL levels and enhance insulin sensitivity in mice fed with HFD.

Angelicin Alleviates Maternal Isoflurane Exposure-Induced Offspring Cognitive Defects Through the Carbonic Anhydrase 4/Aquaporin-4 Pathway

An increasing number of studies reveal the deleterious effects of isoflurane (Iso) exposure during pregnancy on offspring cognition. However, no effective therapeutic strategy for Iso-induced deleterious effects has been well developed. Angelicin exerts an anti-inflammatory effect on neurons and glial cells. This study investigated the roles and mechanism of action of angelicin in Iso-induced neurotoxicity in vitro and in vivo. After exposing C57BL/6 J mice on embryonic day 15 (E15) to Iso for 3 and 6 h, respectively, neonatal mice on embryonic day 18 (E18) displayed obvious anesthetic neurotoxicity, which was revealed by the elevation of cerebral inflammatory factors and blood-brain barrier (BBB) permeability and cognitive dysfunction in mice. Angelicin treatment could not only significantly reduce the Iso-induced embryonic inflammation and BBB disruption but also improve the cognitive dysfunction of offspring mice. Iso exposure resulted in an increase of carbonic anhydrase (CA) 4 and aquaporin-4 (AQP4) expression at both mRNA and protein levels in vascular endothelial cells and mouse brain tissue collected from neonatal mice on E18. Remarkably, the Iso-induced upregulation of CA4 and AQP4 expression could be partially reversed by angelicin treatment. Moreover, GSK1016790A, an AQP4 agonist, was used to confirm the role of AQP4 in the protective effect of angelicin. Results showed that GSK1016790A abolished the therapeutic effect of angelicin on Iso-induced inflammation and BBB disruption in the embryonic brain and on the cognitive function of offspring mice. In conclusion, angelicin may serve as a potential therapeutic for Iso-induced neurotoxicity in neonatal mice by regulating the CA4/AQP4 pathway.

Trafficking of carbonic anhydrase 12 and bicarbonate transporters by histamine stimulation mediates intracellular acidic scenario in lung cancer cells

Carbonic anhydrase 12 is considered an oncogenic and acidic microenvironmental factor in cancer cells. To verify the role of histamine signalling as an anti-cancer signal, we determined the roles of CA12 and its associated bicarbonate transporters. In this study, histamine stimulation mediated mislocalization of CA12 in lung cancer cells. Histamine receptor activation-mediated CA12 endocytosis and pH were restored by CaMKII inhibition. CA12-associated AE2 expression was enhanced, whereas NBCn1 expression and its activity were reduced by histamine stimulation. Histamine receptor activation-mediated acidification was induced by internalised CA12 and NBCn1 and, at the same time by increased bicarbonate efflux through enhanced AE2 expression. Inhibition of protein trafficking by bafilomycin restored CA12 and AE2 localisation and diminished cellular acidosis. Thus, we verified that histamine stimulation induced an acidic scenario, which revealed trafficking of CA12 and its associated bicarbonate transporters in lung cancer cells and its dysregulated pH modulation may be involved in the histamine signalling-mediated anti-cancer process.

New isoxazolidinyl-based N-alkylethanolamines as new activators of human brain carbonic anhydrases

Carbonic anhydrases (CAs) are widespread metalloenzymes which catalyse the reversible hydration of carbon dioxide (CO₂) to bicarbonate (HCO₃^-) and a proton, relevant in many physiological processes. In the last few years, the involvement of CA activation in different metabolic pathways in the human brain addressed the research to the discovery of novel CA activators. Here, a new series of isoxazoline-based amino alcohols as CA activators was investigated. The synthesis and the CA activating effects towards four human CA isoforms expressed in the human brain, that are hCAs I, II, IV and VII, were reported. The best results were obtained for the (methyl)-isoxazoline-amino alcohols 3 and 5 with K_A values in the submicromolar range (0.52-0.86 µM) towards hCA VII, and a good selectivity over hCA I. Being hCA VII involved in brain function and metabolism, the newly identified CA activators might be promising hit compounds with potential therapeutic applications in ageing, epilepsy or neurodegeneration.

Antihistamines, phenothiazine-based antipsychotics, and tricyclic antidepressants potently activate pharmacologically relevant human carbonic anhydrase isoforms II and VII

Carbonic anhydrases (CAs) are important regulators of pH homeostasis and participate in many physiological and pathological processes. CA activators (CAAs) are becoming increasingly important in the biomedical field since enhancing CA activity may have beneficial effects at neurological level. Here, we investigate selected antihistamines, phenothiazine-based antipsychotics, and tricyclic antidepressants (TCAs) as potential activators of human CAs I, II, IV, and VII. Our findings indicate that these compounds are more effective at activating hCA II and VII compared to hCA I and IV. Overall, hCA VII was the most efficiently activated isoform, particularly by phenothiazines and TCAs. This is especially relevant since hCA VII is the most abundant isoform in the central nervous system (CNS) and is implicated in neuronal signalling and bicarbonate balance regulation. This study offers additional insights into the pharmacological profiles of clinically employed drugs and sets the ground for the development of novel optimised CAAs.

A simple yet multifaceted 90 years old, evergreen enzyme: Carbonic anhydrase, its inhibition and activation

Advances in the carbonic anhydrase (CA, EC 4.2.1.1) research over the last three decades are presented, with an emphasis on the deciphering of the activation mechanism, the development of isoform-selective inhibitors/ activators by the tail approach and their applications in the management of obesity, hypoxic tumors, neurological conditions, and as antiinfectives.

Activation studies with amino acids and amines of a β-carbonic anhydrase from Mammaliicoccus (Staphylococcus) sciuri previously annotated as Staphylococcus aureus (SauBCA) carbonic anhydrase

A β-carbonic anhydrase (CA, EC 4.2.1.1) previously annotated to be present in the genome of Staphylococcus aureus, SauBCA, has been shown to belong to another pathogenic bacterium, Mammaliicoccus (Staphylococcus) sciuri. This enzyme, MscCA, has been investigated for its activation with a series of natural and synthetic amino acid and amines, comparing the results with those obtained for the ortholog enzyme from Escherichia coli, EcoCAβ. The best MscCA activators were D-His, L- and D-DOPA, 4-(2-aminoethyl)-morpholine and L-Asn, which showed K_As of 0.12 - 0.89 µM. The least efficient activators were D-Tyr and L-Gln (K_As of 13.9 - 28.6 µM). The enzyme was also also inhibited by anions and sulphonamides, as described earlier. Endogenous CA activators may play a role in bacterial virulence and colonisation of the host which makes this research topic of great interest.

Carbonic Anhydrase Activators for Neurodegeneration: An Overview

Carbonic anhydrases (CAs) are a family of ubiquitous metal enzymes catalyzing the reversible conversion of CO₂ and H₂O to HCO₃⁻ with the release of a proton. They play an important role in pH regulation and in the balance of body fluids and are involved in several functions such as homeostasis regulation and cellular respiration. For these reasons, they have been studied as targets for the development of agents for treating several pathologies. CA inhibitors have been used in therapy for a long time, especially as diuretics and for the treatment of glaucoma, and are being investigated for application in other pathologies including obesity, cancer, and epilepsy. On the contrary, CAs activators are still poorly studied. They are proposed to act as additional (other than histidine) proton shuttles in the rate-limiting step of the CA catalytic cycle, which is the generation of the active hydroxylated enzyme. Recent studies highlight the involvement of CAs activation in brain processes essential for the transmission of neuronal signals, suggesting CAs activation might represent a potential therapeutic approach for the treatment of Alzheimer’s disease and other conditions characterized by memory impairment and cognitive problems. Actually, some compounds able to activate CAs have been identified and proposed to potentially resolve problems related to neurodegeneration. This review reports on the primary literature regarding the potential of CA activators for treating neurodegeneration-related diseases.

New Histamine-Related Five-Membered N-Heterocycle Derivatives as Carbonic Anhydrase I Activators

A series of histamine (HST)-related compounds were synthesized and tested for their activating properties on five physiologically relevant human Carbonic Anhydrase (hCA) isoforms (I, II, Va, VII and XIII). The imidazole ring of HST was replaced with different 5-membered heterocycles and the length of the aliphatic chain was varied. For the most interesting compounds some modifications on the terminal amino group were also performed. The most sensitive isoform to activation was hCA I (K_A values in the low micromolar range), but surprisingly none of the new compounds displayed activity on hCA II. Some derivatives (1, 3a and 22) displayed an interesting selectivity for activating hCA I over hCA II, Va, VII and XIII.

Binding site comparison for coumarin inhibitors and amine/amino acid activators of human carbonic anhydrases

The first structural analysis comparing the binding mode to the target carbonic anhydrases (CAs, EC 4.2.1.1) of two opposite classes of modulators is presented here: coumarin derivatives act as prodrug CA inhibitors (CAIs), being hydrolyzed by the enzyme esterase activity to 2-hydroxycinnamic acids that occlude the active site entrance; CA activators (CAAs) belonging of the amine and amino acid types, enhance the CA activity by increasing the efficiency of the rate-determining proton shuttling step in the CA catalytic cycle. Analysis of the crystallographic data available for the human CA isoform II in adduct with two coumarin CAIs and some CAAs showed that both types of CA modulators bind in the same region of the enzyme active site, basically interacting with superimposable amino acid residues, that are Trp5, Asn62, His64, Asn67, Gln92, Thr200. A plethora of water molecules also participate in the adducts formation. This structural analysis showed that presence of certain chemical groups in the compound structure is mandatory to produce an activating rather than inhibitory action, such as multiple nitrogen- and oxygen-based moieties capable of shuttling protons or forming extended H-bond networks nearby the proton shuttle residue. This constitutes the only known example among all enzymes of an identical binding site for inhibitors and activators, which, in addition, possess significant pharmacological applications.

Amine- and Amino Acid-Based Compounds as Carbonic Anhydrase Activators

After being rather neglected as a research field in the past, carbonic anhydrase activators (CAAs) were undoubtedly demonstrated to be useful in diverse pharmaceutical and industrial applications. They also improved the knowledge of the requirements to selectively interact with a CA isoform over the others and confirmed the catalytic mechanism of this class of compounds. Amino acid and amine derivatives were the most explored in in vitro, in vivo and crystallographic studies as CAAs. Most of them were able to activate human or non-human CA isoforms in the nanomolar range, being proposed as therapeutic and industrial tools. Some isoforms are better activated by amino acids than amines derivatives and the stereochemistry may exert a role. Finally, non-human CAs have been very recently tested for activation studies, paving the way to innovative industrial and environmental applications.

Effect of amino acids and amines on the activity of the recombinant ι-carbonic anhydrase from the Gram-negative bacterium Burkholderia territorii

We here report a study on the activation of the ι-class bacterial CA from Burkholderia territorii (BteCAι). This protein was recently characterised as a zinc-dependent enzyme that shows a significant catalytic activity (kcat 3.0 × 105 s-1) for the physiological reaction of CO2 hydration to bicarbonate and protons. Some amino acids and amines, among which some proteinogenic derivatives as well as histamine, dopamine and serotonin, showed efficient activating properties towards BteCAι, with activation constants in the range 3.9-13.3 µM. L-Phe, L-Asn, L-Glu, and some pyridyl-alkylamines, showed a weaker activating effect towards BteCAι, with KA values ranging between 18.4 µM and 45.6 µM. Nowadays, no information is available on active site architecture, metal ion coordination and catalytic mechanism of members of the ι-group of CAs, and this study represents another contribution towards a better understanding of this still uncharacterised class of enzymes.

Carbonic anhydrase activation profile of indole-based derivatives

Carbonic Anhydrase Activators (CAAs) could represent a novel approach for the treatment of Alzheimer’s disease, ageing, and other conditions that require remedial achievement of spatial learning and memory therapy. Within a research project aimed at developing novel CAAs selective for certain isoforms, three series of indole-based derivatives were investigated. Enzyme activation assay on human CA I, II, VA, and VII isoforms revealed several effective micromolar activators, with promising selectivity profiles towards the brain-associated cytosolic isoform hCA VII. Molecular modelling studies suggested a theoretical model of the complex between hCA VII and the new activators and provide a possible explanation for their modulating as well as selectivity properties. Preliminary biological evaluations demonstrated that one of the most potent CAA 7 is not cytotoxic and is able to increase the release of the brain-derived neurotrophic factor (BDNF) from human microglial cells, highlighting its possible application in the treatment of CNS-related disorders.

Emerging role of carbonic anhydrase inhibitors

Inhibition of carbonic anhydrase (CA, EC 4.2.1.1) was clinically exploited for decades, as most modern diuretics were obtained considering as lead molecule acetazolamide, the prototypical CA inhibitor (CAI). The discovery and characterization of multiple human CA (hCA) isoforms, 15 of which being known today, led to new applications of their inhibitors. They include widely clinically used antiglaucoma, antiepileptic and antiobesity agents, antitumor drugs in clinical development, as well as drugs for the management of acute mountain sickness and idiopathic intracranial hypertension (IIH). Emerging roles of several CA isoforms in areas not generally connected to these enzymes were recently documented, such as in neuropathic pain, cerebral ischemia, rheumatoid arthritis, oxidative stress and Alzheimer's disease. Proof-of-concept studies thus emerged by using isoform-selective inhibitors, which may lead to new clinical applications in such areas. Relevant preclinical models are available for these pathologies due to the availability of isoform-selective CAIs for all human isoforms, belonging to novel classes of compounds, such as coumarins, sulfocoumarins, dithiocarbamates, benzoxaboroles, apart the classical sulfonamide inhibitors. The inhibition of CAs from pathogenic bacteria, fungi, protozoans or nematodes started recently to be considered for obtaining anti-infectives with a new mechanism of action.