Sultam based Carbonic Anhydrase VII inhibitors for the management of neuropathic pain

Dual inhibition of carbonic anhydrases VA and VII by silychristin and isosilybin A from Silybum marianum: A potential antiobesity strategy

Obesity is a global health crisis linked to chronic diseases like cardiovascular disease and type 2 diabetes. Its prevalence, even in low-income countries, highlights the failure of traditional interventions. Safer pharmacological treatments are urgently needed, as many existing antiobesity drugs have been withdrawn due to severe side effects, leaving a critical therapeutic gap. A promising target in this context is human carbonic anhydrase V (hCA V), a mitochondrial enzyme that plays a key role in glucose homeostasis. Inhibiting hCA V has been shown to reduce lipogenesis and improve metabolic conditions. Natural plant extracts, such as silymarin from milk thistle, have demonstrated potential in managing obesity-related metabolic syndromes by lowering triglycerides, reducing cholesterol levels, and improving liver function. Our computational studies have identified active compounds in silymarin that effectively inhibit hCA V, shedding light on a potential mechanism for its antiobesity effects. Building on these findings, our research further reveals that these compounds also inhibit carbonic anhydrase VII (hCA VII), enhancing their therapeutic potential. This dual inhibitory action addresses both metabolic dysregulation and oxidative stress. Notably, the antioxidant properties of hCA VII provide additional protection against obesity-related complications by mitigating oxidative stress, a key contributor to the development of metabolic syndrome.

Synthesis, characterization, antimicrobial, cytotoxic and carbonic anhydrase inhibition activities of multifunctional pyrazolo-1,2-benzothiazine acetamides

The advent of antibiotic resistance in microorganisms requires the discovery and synthesis of novel antibiotics. At the same time, human pathogens are contributing to chronic and persistent inflammation. Motivated by these two concerning issues, new antibiotic drug candidates are synthesized by incorporation of benzothiazine, pyrazole, and amide moieties in a new scaffold to create multifunctional derivatives of pyrazolo-1,2-benzothiazine. The presented compounds have been synthesized and analyzed using spectroscopic and spectrometric techniques including FTIR, HRMS, 1H and 13C NMR spectroscopy. All compounds were tested against five human microbial strains including three different strains of Staphylococcus aureus (ATCC 25923, ATCC BAA-41, and ATCC BAA-44), Escherichia coli (ATCC 8739), and Candida albicans (ATCC 90027) to evaluate their antibiotic potential. The results showed that out of fourteen synthesized compounds, 7b (MIC90 = 16 μg/mL) and 7h (MIC90 = 8.0 μg/mL) exhibited potent antibiotic activity against different strains of S. aureus (susceptible, methicillin-resistant, and multidrug-resistant). Cytotoxic studies against the human colon cancer mammalian cell line HCT-116 (ATCC CCL-247) revealed that only compound 7l inhibited cell viability, while the rest of the compounds including 7b and 7h showed no significant decrease in mammalian cell viability. Results of human carbonic anhydrase (hCA) inhibition assays discovered that monoalkylated derivatives have low to negligible inhibition potential but dialkylated ones have no inhibition potential at all for directed CAs (I, II, IX, and XII). From the low inhibiting compounds, 7b showed the highest inhibition potential with a minimum K i value of 72.9 μM. In light of the above findings, these newly prepared scaffolds are valuable additions to the class of pyrazolo-1,2-benzothiazine antibiotics with selective antistaphylococcal activity.

Transition metal-catalyzed cascade C-H activation/cyclization with alkynes: an update on sulfur-containing directing groups

In light of the extensive applications of sulfur-containing heterocyclic compounds in drug discovery, agrochemicals, and advanced materials, the construction of complex sulfur-containing molecular scaffolds has flourished in recent years. There is a profound interest in synthetic methods for forming carbon-sulfur bonds. Regarding this, transition metal (TM)-catalyzed C-H bond activation has emerged as a valuable means for the rapid formation of C-S bonds, although it is comparatively less explored than C-N or C-C bonds. The research significance of sulfur-directed C-H activation chemistry lies in maintaining a balance between activating and poisoning the catalyst as well as in the diversity and novelty of its properties. This review centers on sulfur-directed TM-catalyzed cascade C-H activation/cyclization with alkyne and encompasses the literature mainly from 2012 to 2024. The widely acknowledged reactivity and versatility of rhodium, ruthenium, and cobalt catalysts have given rise to various captivating cascade processes. For most reactions illustrated in this review, reactivity and selectivity are attained through the flexible synergistic combination of different metal catalysts and additives. Further advancements will be accompanied with the discovery of innovative sulfur-directing groups, chiral catalysis, and ground-breaking experimental techniques. This article will also inspire researchers to gain a deeper understanding of the mechanism, thus undoubtedly leading to innovations and more discoveries in the future.

Base-Controlled Synthesis of Heteroatom-Embedded 9-Membered Cycloalkynes and 6-Membered Sultams through Copper-Catalyzed Cyclization

A facile copper-catalyzed, base-controlled cyclization reaction has been developed for the synthesis of 9-membered cycloalkyne and 6-membered heterocycle sultams under mild conditions. This protocol utilizes a copper-catalyzed intramolecular A3 (alkyne-aldehyde-amine) coupling reaction to efficiently synthesize 9-membered cycloalkyne sultams in yields up to 90%. Alternatively, by substituting NaHCO3 with DBU, the protocol achieves selective deprotection of the N-propargyl group, thereby facilitating the formation of 6-membered heterocyclic sultams, also in high yields.

WTAP mediates IL-1β-induced chondrocyte injury by enhancing CA12 mRNA stability depending on m6A modification

BACKGROUND

Osteoarthritis (OA) poses a significant risk to the mobility of patients. Carbonic anhydrase 12 (CA12) can boost apoptosis and inflammation in several cancers, but its role in OA is unknown.

METHODS

Differentially expressed genes in OA were analyzed using the GEO database (GSE169077). RT-qPCR and western blot estimated relative mRNA and protein levels of CA12. Cell viability and apoptosis were estimated by cell counting and flow cytometry assays. Oxidative stress (OxS) was determined by detecting with ROS and MDA levels, as well as CAT and SOD activities. Cytokine levels of IL-6 and TNF-α were detected by ELISA. Parameters associated with apoptosis and extracellular matrix (ECM) were detected by western blot. The m6A modification profile was determined by methylated RNA immunoprecipitation assays.

RESULTS

Relative CA12 and wilms' tumor 1-associating protein (WTAP) mRNA and protein levels were overexpressed in OA articular cartilages and IL-1β-challenged chondrocytes CHON-001. CA12 silencing impaired IL-1β-induced cell apoptosis, inflammation, OxS, and ECM degradation in chondrocytes. Yet, CA12 overexpression exerted an opposing function. WTAP reinforced the stability of CA12 mRNA depending on the m6A modification. Furthermore, WTAP knockdown weakened cell apoptosis, inflammation, OxS, and ECM degradation in chondrocytes induced by IL-1β, but these changes were impaired after CA12 overexpression. In addition, WTAP knockdown mitigates cartilage degeneration in DMM-induced mouse models.

CONCLUSION

IL-1β-induced WTAP enhances CA12 mRNA stability depending on m6A modification, thus promoting chondrocyte apoptosis, inflammatory response, OxS, and ECM degradation, providing evidence to support the possibility of WTAP and CA12 as potential targets for OA treatment.

Unveiling sultam in drug discovery: spotlight on the underexplored scaffold

Decades ago, the application of cyclic sulfonamide (sultam) and its derivatives primarily focused on their antibacterial properties. However, recent years have seen a shift in research attention towards exploring their potential as anticancer, anti-inflammatory, antidiabetic, and antiviral agents. Despite this broadening scope, only a few sultam drugs have made it to the commercial market, as much of the research on sultams remains in the discovery phase. This class of compounds holds significant promise and remains pertinent in pharmaceutical research. Due to sultam's relevance and growing importance in drug discovery, this review paper aims to consolidate and examine the biological activities of sultam derivatives ranging from 4 to 8-membered ring structures.

Conformationally Restricted Glycoconjugates Derived from Arylsulfonamides and Coumarins: New Families of Tumour-Associated Carbonic Anhydrase Inhibitors

The involvement of carbonic anhydrases (CAs) in a myriad of biological events makes the development of new inhibitors of these metalloenzymes a hot topic in current Medicinal Chemistry. In particular, CA IX and XII are membrane-bound enzymes, responsible for tumour survival and chemoresistance. Herein, a bicyclic carbohydrate-based hydrophilic tail (imidazolidine-2-thione) has been appended to a CA-targeting pharmacophore (arylsulfonamide, coumarin) with the aim of studying the influence of the conformational restriction of the tail on the CA inhibition. For this purpose, the coupling of sulfonamido- or coumarin-based isothiocyanates with reducing 2-aminosugars, followed by the sequential acid-promoted intramolecular cyclization of the corresponding thiourea and dehydration reactions, afforded the corresponding bicyclic imidazoline-2-thiones in good overall yield. The effects of the carbohydrate configuration, the position of the sulfonamido motif on the aryl fragment, and the tether length and substitution pattern on the coumarin were analysed in the in vitro inhibition of human CAs. Regarding sulfonamido-based inhibitors, the best template turned out to be a d-galacto-configured carbohydrate residue, meta-substitution on the aryl moiety (9b), with K_i against CA XII within the low nM range (5.1 nM), and remarkable selectivity indexes (1531 for CA I and 181.9 for CA II); this provided an enhanced profile in terms of potency and selectivity compared to more flexible linear thioureas 1-4 and the drug acetazolamide (AAZ), used herein as a reference compound. For coumarins, the strongest activities were found for substituents devoid of steric hindrance (Me, Cl), and short linkages; derivatives 24h and 24a were found to be the most potent inhibitors against CA IX and XII, respectively (K_i = 6.8, 10.1 nM), and also endowed with outstanding selectivity (K_i > 100 µM against CA I, II, as off-target enzymes). Docking simulations were conducted on 9b and 24h to gain more insight into the key inhibitor-enzyme interactions.

Uncovering Novel Capsaicin Inhibitory Activity towards Human Carbonic Anhydrase Isoforms IX and XII by Combining In Silico and In Vitro Studies

Hot pepper (Capsicum annuum) represents one of the most widespread functional foods of the Mediterranean diet, and is associated with a reduced risk of developing cardiovascular disease, cancer, and mental disorders. In particular, its bioactive spicy molecules, named Capsaicinoids, exhibit polypharmacological properties. Among them, Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) is the most studied and reported in variegated scientific contributions for its beneficial effects, often linked to mechanisms of action unrelated to the activation of Transient Receptor Potential Vanilloid 1 (TRPV1). In this study, we present the application of in silico methods to Capsaicin for evaluating its inhibitory activity against the tumor-associated human (h) expressed CA IX and XII. In vitro assays confirmed Capsaicin inhibitory activity towards the most relevant tumor-related hCA isoforms. In particular, the hCAs IX and XII showed an experimental K_I value of 0.28 μM and 0.064 μM, respectively. Then, an A549 model of non-small cell lung cancer, typically characterized by an elevated expression of hCA IX and XII, was employed to test the inhibitory effects of Capsaicin in vitro under both normoxic and hypoxic conditions. Finally, the migration assay revealed that Capsaicin [10 µM] inhibits cells from moving in the A549 cells model.

Small Structural Differences Govern the Carbonic Anhydrase II Inhibition Activity of Cytotoxic Triterpene Acetazolamide Conjugates

Acetylated triterpenoids betulin, oleanolic acid, ursolic acid, and glycyrrhetinic acid were converted into their succinyl-spacered acetazolamide conjugates. These conjugates were screened for their inhibitory activity onto carbonic anhydrase II and their cytotoxicity employing several human tumor cell lines and non-malignant fibroblasts. As a result, the best inhibitors were derived from betulin and glycyrrhetinic acid while those derived from ursolic or oleanolic acid were significantly weaker inhibitors but also of diminished cytotoxicity. A betulin-derived conjugate held a K_i = 0.129 μM and an EC₅₀ = 8.5 μM for human A375 melanoma cells.

Resveratrol Analogues as Dual Inhibitors of Monoamine Oxidase B and Carbonic Anhydrase VII: A New Multi-Target Combination for Neurodegenerative Diseases?

Neurodegenerative diseases (NDs) are described as multifactorial and progressive syndromes with compromised cognitive and behavioral functions. The multi-target-directed ligand (MTDL) strategy is a promising paradigm in drug discovery, potentially leading to new opportunities to manage such complex diseases. Here, we studied the dual ability of a set of resveratrol (RSV) analogs to inhibit two important targets involved in neurodegeneration. The stilbenols 1−9 were tested as inhibitors of the human monoamine oxidases (MAOs) and carbonic anhydrases (CAs). The studied compounds displayed moderate to excellent in vitro enzyme inhibitory activity against both enzymes at micromolar/nanomolar concentrations. Among them, the best compound 4 displayed potent and selective inhibition against the MAO-B isoform (IC50 MAO-A 0.43 µM vs. IC50 MAO-B 0.01 µM) with respect to the parent compound resveratrol (IC50 MAO-A 13.5 µM vs. IC50 MAO-B > 100 µM). It also demonstrated a selective inhibition activity against hCA VII (KI 0.7 µM vs. KI 4.3 µM for RSV). To evaluate the plausible binding mode of 1−9 within the two enzymes, molecular docking and dynamics studies were performed, revealing specific and significant interactions in the active sites of both targets. The new compounds are of pharmacological interest in view of their considerably reduced toxicity previously observed, their physicochemical and pharmacokinetic profiles, and their dual inhibitory ability. Compound 4 is noteworthy as a promising lead in the development of MAO and CA inhibitors with therapeutic potential in neuroprotection.

Identification of New Carbonic Anhydrase VII Inhibitors by Structure-Based Virtual Screening

Human carbonic anhydrase VII (hCA VII) constitutes a promising molecular target for the treatment of epileptic seizures and other central nervous system disorders due to its almost exclusive expression in neurons. Achieving isoform selectivity is one of the main challenges for the discovery of new hCA inhibitors, since nonspecific inhibition may lead to tolerance and side effects. In the present work, we report the development of a molecular docking protocol based on AutoDock4_Zn for the search of new hCA VII inhibitors by virtual screening. The docking protocol was applied to the screening of two sets of compounds: a ZINC15 subset of sulfur-containing structures and an in-house library consisting of synthetic and commercial candidates (including approved drugs). Five compounds were selected from the first screening campaign and three from the second one, and they were tested in vitro against the enzyme. Among the eight selected structures, four showed K_i values in the low nanomolar range. These confirmed hits include three approved drugs: meloxicam, piroxicam, and nitrofurantoin, which also showed good selectivity for hCA VII versus hCA II.

Squaramide-Tethered Sulfonamides and Coumarins: Synthesis, Inhibition of Tumor-Associated CAs IX and XII and Docking Simulations

(1) Background: carbonic anhydrases (CAs) are attractive targets for the development of new anticancer therapies; in particular, CAs IX and XII isoforms are overexpressed in numerous tumors. (2) Methods: following the tail approach, we have appended a hydrophobic aromatic tail to a pharmacophore responsible for the CA inhibition (aryl sulfonamide, coumarin). As a linker, we have used squaramides, featured with strong hydrogen bond acceptor and donor capacities. (3) Results: Starting from easily accessible dimethyl squarate, the title compounds were successfully obtained as crystalline solids, avoiding the use of chromatographic purifications. Interesting and valuable SARs could be obtained upon modification of the length of the hydrocarbon chain, position of the sulfonamido moiety, distance of the aryl sulfonamide scaffold to the squaramide, stereoelectronic effects on the aromatic ring, as well as the number and type of substituents on C-3 and C-4 positions of the coumarin. (4) Conclusions: For sulfonamides, the best profile was achieved for the m-substituted derivative 11 (Ki = 29.4, 9.15 nM, CA IX and XII, respectively), with improved selectivity compared to acetazolamide, a standard drug. Coumarin derivatives afforded an outstanding selectivity (Ki > 10,000 nM for CA I, II); the lead compound (16c) was a strong CA IX and XII inhibitor (Ki = 19.2, 7.23 nM, respectively). Docking simulations revealed the key ligand-enzyme interactions.

Inhibitors of Mitochondrial Human Carbonic Anhydrases VA and VB as a Therapeutic Strategy against Paclitaxel-Induced Neuropathic Pain in Mice

Neuropathy development is a major dose-limiting side effect of anticancer treatments that significantly reduces patient's quality of life. The inadequate pharmacological approaches for neuropathic pain management warrant the identification of novel therapeutic targets. Mitochondrial dysfunctions that lead to reactive oxygen species (ROS) increase, cytosolic Ca²⁺ imbalance, and lactate acidosis are implicated in neuropathic pain pathogenesis. It has been observed that in these deregulations, a pivotal role is played by the mitochondrial carbonic anhydrases (CA) VA and VB isoforms. Hence, preclinical studies should be conducted to assess the efficacy of two novel selenides bearing benzenesulfonamide moieties, named 5b and 5d, and able to inhibit CA VA and VB against paclitaxel-induced neurotoxicity in mice. Acute treatment with 5b and 5d (30-100 mg/kg, per os - p.o.) determined a dose-dependent and long-lasting anti-hyperalgesic effect in the Cold plate test. Further, repeated daily treatment for 15 days with 100 mg/kg of both compounds (starting the first day of paclitaxel injection) significantly prevented neuropathic pain development without the onset of tolerance to the anti-hyperalgesic effect. In both experiments, acetazolamide (AAZ, 100 mg/kg, p.o.) used as the reference drug was partially active. Moreover, ex vivo analysis demonstrated the efficacy of 5b and 5d repeated treatments in reducing the maladaptive plasticity that occurs to glia cells in the lumbar portion of the spinal cord and in improving mitochondrial functions in the brain and spinal cord that were strongly impaired by paclitaxel-repeated treatment. In this regard, 5b and 5d ameliorated the metabolic activity, as observed by the increase in citrate synthase activity, and preserved an optimal mitochondrial membrane potential (ΔΨ) value, which appeared depolarized in brains from paclitaxel-treated animals. In conclusion, 5b and 5d have therapeutic and protective effects against paclitaxel-induced neuropathy without tolerance development. Moreover, 5b and 5d reduced glial cell activation and mitochondrial dysfunction in the central nervous system, being a promising candidate for the management of neuropathic pain and neurotoxicity evoked by chemotherapeutic drugs.

Pd-catalysed intramolecular transformations of indolylbenzenesulfonamides: ortho-sulfonamido-bi(hetero)aryls via C2-arylation and polycyclic sultams via C3 arylation

Indolyl substituted iodo-sulfonamides deliver 2-aryl(sulfonamido)indoles in the presence of Pd(OAc)2/Ph3P/Et3N; the same reactants, using Pd(OAc)2/Ph3P/K2CO3, afford indole-fused sultams.