Human carbonic anhydrase XII (hCA XII) represents an important pharmacological target for different types of cancer. hCA XII plays a crucial role in regulating both extracellular and intracellular pH, thereby influencing cancer cell proliferation, invasion, growth, and metastasis. Although the interaction features of hCA inhibitors (hCAIs) with the catalytic site of distinct hCA isoforms are generally well described, the lack of selectivity remains a major challenge. In a previous work, we have reported a series of 1-aryl-6,7-dimethoxy-3,4-dihydroisoquinoline-2(1H)-sulfonamides displaying weak activity against the ubiquitous hCA I and hCA II, thus emerging as hCAIs that may be free of unwanted side-effects. Herein, further evaluation of their CA inhibitory effects allowed to disclose three potent hCA XII inhibitors at low nanomolar concentrations (Ki values ranging from 5.5 to 6.5 nM). Additionally, they showed remarkable isoform selectivity compared with the well-known inhibitor SLC-0111, currently in clinical trials as an antitumor agent. Crystallography analyses and computational studies clarified the molecular basis of this behavior and provided valuable insights for the rational design of selective inhibitors targeting hCA XII.

Chirality plays a central role in molecular recognition, and systems combining multiple, interdependent chiral elements can offer enhanced enantioselectivity. Here we show that covalent tethering of a dihydroxy-pillar[5]arene with meso-2,11-dibromododecanedioate yields diastereomeric pseudo[1]catenanes that combine three stereogenic features: two point chiral centers within the aliphatic linker, a helical chirality (P/M) induced by macrocycle closure, and a planar chirality of the pillararene ring. This system exhibits dynamic stereochemical behaviour involving in/out conformational equilibria, accompanied by inversion of the planar chirality. Using NMR spectroscopy, X-ray diffraction, DFT calculations and circular dichroism, we characterize the structures and dynamics of these macrobicyclic pillararenes, including guest-induced inclusion-exclusion processes. Hydrolysis affords a dicarboxyl-functionalized receptor capable of recognizing diamines via host-to-guest proton transfer, while enantiopure derivatives act as chiroptical sensors able to discriminate between L- and D-lysine esters. These results demonstrate how coupling multiple types of chirality can be exploited for responsive molecular recognition.

Herein we report the chemical derivatization of the naturally occurring Tropolone (TRP) and its related compound β-Thujaplicin (β-TJP) as well as their in vitro assessment for inhibition of the physio/pathologically relevant hCAs isoforms I, II, VA; VII, IX and XII to obtain a first set of inhibition data useful for driving selected derivatives towards appropriate biomedical exploitation. The selected compound 17β was characterized for its chemical stability and assessed for its antiproliferative activity on a multiple myeloma model and showed potent pro-apoptotic features jointly with a safe toxicity profile on healthy cells. The binding mode of β-TJP within the hCA II was assessed by means of X-ray crystallography of the hCA II/β-TJP complex and showed almost complete superposition with the hCA II/TRP adduct reported in the literature. The data produced were used to elaborate a binding prediction model of such compounds on the hCAs VA, IX, and XII which are directly connected to important diseases. Overall, the achievements reported in this work are in the sustainment of the exploitation of naturally occurring troponoloid-based structures for biomedical purposes and thus contribute to the field in extending the variety of available chemical features.

Human elastase 1 has been shown to possess an important role in maintaining skin stability and elasticity through the proteolytic cleavage of elastin (ELN), a hydrophobic protein that serves as a key component of extracellular matrix in the skin. The development of antielastase agents represents a promising therapeutic approach for treating skin pathologies characterized by elastin degradation, with applications in both dermatology and cosmetology. Reversible inhibitors represent a therapeutic strategy, offering selective inhibition of elastase proteolytic activity while preserving the function of other physiologically essential serine proteases. Using porcine pancreatic elastase (PPE) as a well-established surrogate of human skin elastase, a focused series of noncovalent inhibitors designed to bind the catalytic area of PPE is assayed. Several compounds display an antielastase activity, including N-(2-bromophenyl)-2-(6-chloro-1-(3,5-dimethylbenzyl)-1H-benzo[d]imidazol-2-ylthio)acetamide (7) that exhibits the most potent inhibitory effects (IC50 = 41.1 µM), similar to standard compound oleanolic acid (IC50 value of 25.7 µM). The observed structure-activity relationship is further validated through molecular docking and dynamic studies, which provide mechanistic understanding of the binding interactions and establish suggestions for further rational drug design.

The growing interest in Kv7.2/7.3 agonists originates from the involvement of these channels in several brain hyperexcitability disorders. In particular, Kv7.2/7.3 mutants have been clearly associated with epileptic encephalopathies (DEEs) as well as with a spectrum of focal epilepsy disorders, often associated with developmental plateauing or regression. Nevertheless, there is a lack of available therapeutic options, considering that retigabine, the only molecule used in clinic as a broad-spectrum Kv7 agonist, has been withdrawn from the market in late 2016. This is why several efforts have been made both by both academia and industry in the search for suitable chemotypes acting as Kv7.2/7.3 agonists. In this context, in silico methods have played a major role, since the precise structures of different Kv7 homotetramers have been only recently disclosed. In the present review, the computational methods used for the design of Kv.7.2/7.3 small molecule agonists and the underlying medicinal chemistry are discussed in the context of their biological and structure-function properties.

In this two-session experiment for an organic chemistry lab, students prepare a macrocyclic host compound & horbar;namely, a pillar[5]arene & horbar;by means of a templated 1,4-dimethoxybenzene/formaldehyde cyclo-oligomerization (session 1), and then, they explore its molecular recognition properties toward the 1,8-diaminooctane guest with the aid of H-1 NMR spectroscopy (session 2). The acid-catalyzed synthesis of decamethyl-pillar[5]arene provides, in good yield, a product sufficiently pure to be directly used in the subsequent NMR titration experiment. The two-session experiment targets advanced chemistry students, whereas the 4 h synthesis of the macrocycle (session 1) may be included in an introductory organic chemistry laboratory course. This experiment links concepts spanning from classical SEAr reactions to macrocycle synthesis down to host-guest chemistry, NMR spectroscopy, and data treatment, providing a useful connection between organic chemistry synthesis and supramolecular chemistry.

Over the last ten years, researchers’ efforts have aimed to replace the classic linear economy model with the circular economy model, favoring green chemical and industrial processes. From this point of view, biologically active molecules, coming from plants, flowers and biomass, are gaining considerable value. In this study, firstly we focus on the development of a green protocol to obtain the purification of anthocyanins from the flower of Callistemon citrinus, based on simulation and on response surface optimization methodology. After that, we utilize them to manufacture and add new properties to bioplastics belonging to class 3, based on modified polyvinyl alcohol (PVA) with increasing amounts from 0.10 to 1.00%. The new polymers are analyzed to monitor morphological changes, optical properties, mechanical properties and antioxidant and antimicrobial activities. Fourier transform infrared spectroscopy (FTIR) spectra of the new materials show the characteristic bands of the PVA alone and a modification of the band at around 1138 cm−1 and 1083 cm−1, showing an influence of the anthocyanins’ addition on the sequence with crystalline and amorphous structures of the starting materials, as also shown by the results of the mechanical tests. These last showed an increase in thickening (from 29.92 μm to approx. 37 μm) and hydrophobicity with the concomitant increase in the added anthocyanins (change in wettability with water from 14° to 31°), decreasing the poor water/moisture resistance of PVA that decreases its strength and limits its application in food packaging, which makes the new materials ideal candidates for biodegradable packaging to extend the shelf-life of food. The functionalization also determines an increase in the opacity, from 2.46 to 3.42 T%/mm, the acquisition of antioxidant activity against 2,2-diphenyl-1-picrylhdrazyl and 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) radicals and, in the ferric reducing power assay, the antimicrobial (bactericidal) activity against different Staphylococcus aureus strains at the maximum tested concentration (1.00% of anthocyanins). On the whole, functionalization with anthocyanins results in the acquisition of new properties, making it suitable for food packaging purposes, as highlighted by a food fresh-keeping test.

A small series of arylsulfonamide derivatives was designed and synthesized to study linear and cyclic inhibitors targeting human Carbonic Anhydrases (hCAs EC 4.2.1.1) as essential enzymes regulating (patho)-physiological processes. Particularly, the synthesis of these ten compounds was inspired to the well-known arylsulfonamides having flexible or constrained linkers able to maintain the two crucial moieties, anchoring zinc group and hydrophobic tail, in the optimized orientation within CA cavities of tumor-expressed isoforms hCA IX and hCA XII. The synthesized imine derivatives and related cyclic 1,3-thiazin-4-ones were screened in a stopped-flow carbon dioxide hydrase assay and proved to be effective inhibitors against hCA IX and hCA XII isoforms with K-i values ranging of 3.7-215.7 nM and 5.7-415.0 nM, respectively. Molecular docking studies of both series of arylsulfonamides were conducted to propose their binding mode within hCA IX and hCA XII active sites thus highlighting their distinct ability to occupy the two catalytic cavities. Moreover, the 4-[(3-cyanophenyl)methylidene]aminobenzene-1-sulfonamide 7 proved to reduce the cell viability of breast carcinoma (MCF-7) and colon rectal carcinoma (HCT-116) human cell lines under the fixed doses of 10 mu M. These results encouraged us to continue our efforts in developing potent and efficient arylsulfonamides targeting hCA IX and hCA XII isoforms.

The supramolecular polymerization of a bis-pillar[5]arene dicarboxylic acid monomer (H) in the presence of a mixture of complementary bis-guests 1,12-dodecanediyl-bis-1,1 '-1H-imidazole (G1) and bis-N,N'-(6-(1H-imidazole)decyl)-perylene bisimide (G2), produces an AA/BB-type supramolecular copolymer H/G1/G2 that retains the properties of the parent bi-component systems, that is, H/G1 solubility and H/G2 photoresponsiveness. The supramolecular copolymer showed stimuli-responsiveness, reacting to the presence of the cancer marker, spermine (S), by disassemblying and releasing G2. Once released, the perylene bisimide monomer (quenched in the copolymer by host-to-guest electron transfer), showed a remarkable increase of emission intensity. ESI-MS data are fully consistent with the formation of the H/G1/G2 copolymer, and AFM investigations on films cast from H/G1/G2 and H/G1/G2 + S solutions demonstrated that the supramolecular copolymer sensing abilities are retained also in the solid state. A supramolecular copolymer, composed of a bis-pillar[5]arene diacid and complementary alkylidene- and perylene-bisimide-bis-imidazole comonomers, acts as an OFF/ON luminescent sensor for spermine.

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

The protonation constants of quinaldic acid (QA), 8-hydroxyquinoline (8-HQ) and 8-hydroxyquinoline-2-carboxylic acid (8-HQA) were determined potentiometrically in KCl(aq) at I = 0.2 mol dm(-3) at different temperatures (288.15 <= T/K <= 318.15). Their temperature dependence was modeled by the van't Hoff equation, which allowed the calculation of other thermodynamic parameters, such as Delta H-0 and Delta S-0. Protonation enthalpy changes were also experimentally determined by isothermal titration calorimetry (ITC) at T = 298.15 K in the same medium and ionic strength conditions. From the obtained results, it emerged that all stepwise protonation reactions for the three ligands are exothermic, with protonation constants decreasing with increasing temperature. Then, thermodynamic protonation parameters obtained by both approaches were critically analyzed and compared, evidencing that protonation enthalpy changes obtained experimentally by direct calorimetry are more accurate than those derived by the van't Hoff equation. However, the latter approach proved useful to evidence possible variability of this thermodynamic parameter with temperature, thus allowing the eventual calculation of the corresponding Delta C-P. Furthermore, on the basis of both the analysis of the obtained parameters and the results of detailed 1D and 2D H-1 NMR studies, it was possible to unequivocally determine the protonation sequence of the different functional groups of 8-HQA (as well as QA and 8-HQ): from basic to acidic pH, the first group to undergo protonation is the phenolate, followed by the quinolinic nitrogen and, finally, by the carboxylate.

The antifungal activity of molecules belonging to the arylsulfonamide chemotype has previously been demonstrated. Here, we screened arylsulfonamide-type compounds against a range of Candida spp. and further established the structure–activity relationship based on a “hit compound”. A series of four sulfonamide-based compounds, N-(4-sulfamoylbenzyl) biphenyl-4-carboxamide (3), 2,2-diphenyl-N-(4-sulfamoylbenzyl) acetamide (4), N-(4-sulfamoylphenethyl) biphenyl-4-carboxamide (5) and 2,2-diphenyl-N-(4-sulfamoylphenethyl) acetamide (6), were tested against the American Type Culture Collection (ATCC) and clinical strains of C. albicans, C. parapsilosis and C. glabrata. Based on the fungistatic potential of prototype 3, a further subset of compounds, structurally related to hit compound 3, was synthesized and tested: two benzamides (10–11), the related amine 4-[[(4-4-((biphenyl-4-ylmethylamino)methyl) benzenesulfonamide (13) and the corresponding hydrochloride, 13.HCl. Both amine 13 and its hydrochloride salt had fungicidal effects against Candida glabrata strain 33 (MFC of 1.000 mg/mL). An indifferent effect was detected in the association of the compounds with amphotericin B and fluconazole. The cytotoxicity of the active compounds was also evaluated. This data could be useful to develop novel therapeutics for topical use against fungal infections.

Tetraamino-dihydroxy-oxacalix[4]arenes 1 center dot H64+center dot 4Cl- and 2 center dot H64+center dot 4Cl- were synthesized in two steps from off-the-shelf components, and subjected to in-depth investigations on their molecular and supramolec-ular properties. UV-Vis titrations with aqueous NaOH provided six discrete protonation constants along with the distribution diagram for each of the oxacalixarenes, while a 1H NMR titration of 1 center dot H64+center dot 4Cl- with NaOD(aq), combined with DFT (B3LYP/6-311++G(d,p)) calculations allowed to shed light on the conforma-tional preferences of macrocycle 1 center dot Hn(n-2)+ in the different protonation states. 1H NMR titrations with N, N'-dimethyl-4,4'-bipyridinium (paraquat) dichloride gave, at different pH values, apparent association constants (Kapp) for the formation of the host-guest complexes. Kapp values, combined with the protona-tion constants, in turn provided the stability constant for the individual complexes between paraquat and 1 center dot Hn(n-2)+ in the different states of ionization, and allowed to identify 1 center dot H- as the most efficient paraquat receptor.(c) 2022 Elsevier B.V. All rights reserved.

This study reports our continued efforts to identify inhibitors capable of targeting carbonic anhydrases (CAs) expressed in bacteria. Based on previously identified chemotypes, we designed and synthesized new analogs that were screened toward the α, β, and γ classes encoded in Vibrio cholerae (Vch). The Ki values measured in the stopped-flow hydrase assay revealed that very simple structural modifications might induce a relevant impact on the inhibitory effects as well as the selectivity profile over ubiquitous human isozymes (hCA I/II). Unfortunately, the best active VchCA inhibitors demonstrated a dramatic loss of hCA II selectivity when compared to previously reported compounds. Among the new series of sulfonamides, several molecules proved to be about sevenfold more potent against VchCAγ than the reference compound acetazolamide, thus furnishing new insights for further development of inhibitors targeting CAs expressed in bacteria.

Ammonium ion/carboxylate ion pairing is a key interaction ubiquitous in biological systems, but amine recognition by ionizable molecular receptors, mediated by host-to-guest proton transfer, has too often been overlooked as a design element for molecular recognition. This survey will show that proton transfer mediated recognition is a powerful and versatile tool that can be made to work with different amines and diverse macrocyclic scaffolds, such as crown ethers, calixarenes or pillararenes. We will trace the history of this recognition motif since Cram's first report half a century ago down to the latest applications in supramolecular sensing, drug-delivery and materials science, highlighting along the way the impact of host-to-guest proton transfer on self-assembly and molecular recognition.

Given the increased antimicrobial resistance, global effort is currently focused on the identification of novel compounds, both of natural and chemical origin. The present study reports on the antifungal potential of 1-(1H-indol-3-yl) derivatives, previously known as tyrosinase inhibitors. The effect of seven compounds (indicated as 3a–g) was determined against Candida albicans ATCC 10531, three clinical isolates of Candida albicans, two clinical isolates of Candida glabrata, two clinical isolates of Candida parapsilosis and Aspergillus niger ATCC 16404. The effect of these derivatives on tyrosinase enzymatic activity was also evaluated. Results showed a fungicidal activity of compounds 3b, 3c and 3e against all tested strains at concentrations ranging between 0.250 and 1 mg/mL. Furthermore, the association between 3c and fluconazole and between 3b and caspofungin showed a trend of indifference tending toward synergism. Compound 3c was also able to inhibit microbial tyrosinase up to ~28% at the concentration of 0.250 mg/mL. These data could help provide novel therapeutics for topical use to treat fungal infections and increase the potential effectiveness of the association between novel compounds and commercial antifungals in order to combat drug resistance.

A current issue of antimicrobial therapy is the resistance to treatment with worldwide consequences. Thus, the identification of innovative targets is an intriguing challenge in the drug and development process aimed at newer antimicrobial agents. The state‐of‐art of anticholera therapy might comprise the reduction of the expression of cholera toxin, which could be reached through the inhibition of carbonic anhydrases expressed in Vibrio cholerae (VchCAα, VchCAβ, and VchCAγ). Therefore, we focused our interest on the exploitation of sulfonamides as VchCA inhibitors. We planned to design and synthesize new benzenesulfonamides based on our knowledge of the VchCA catalytic site. The synthesized compounds were tested thus collecting useful SAR information. From our investigation, we identified new potent VchCA inhibitors, some of them displayed high affinity toward VchCAγ class, for which few inhibitors are currently reported in literature. The best interesting VchCAγ inhibitor (S)‐N‐(1‐oxo‐1‐((4‐sulfamoylbenzyl)amino)propan‐2‐yl)furan‐2‐carboxamide (40) resulted more active and selective inhibitor when compared with acetazolamide (AAZ) as well as previously reported VchCA inhibitors.

To tackle the challenge of isoform selectivity, we explored the entrance of the cavity for selected druggable human Carbonic Anhydrases (hCAs). Based on X-ray crystallographic studies on the 4-(4-(2-chlorobenzoyl)piperazine-1-carbonyl)benzenesulfonamide in complex with the brain expressed hCA VII (PDB code: 7NC4), a series of 4-(4(hetero)aroylpiperazine-1-carbonyl)benzene-1-sulfonamides has been developed. To evaluate their capability to fit the hCA VII catalytic cavity, the newer benzenesulfonamides were preliminary investigated by means of docking simulations. Then, this series of thirteen benzenesulfonamides was synthesized and tested against selected druggable hCAs. Among them, the 4-(4-(furan-2-carbonyl)piperazine-1-carbonyl)benzenesulfonamide showed remarkable affinity towards hCA VII (Ki: 4.3 nM) and good selectivity over the physiologically widespread hCA I when compared to Topiramate (TPM).

Carbonic anhydrases from Vibrio cholerae (VchCAs) play a significant role in bacterial pathophysiological processes. Therefore, their inhibition leads to a reduction of gene expression virulence and bacterial growth impairment. Herein, we report the first ligand-based pharmacophore model as a computational tool to study selective inhibitors of the β-class of VchCA. By a virtual screening on a collection of sulfonamides, we retrieved 9 compounds that were synthesized and evaluated for their inhibitory effects against VchCAβ as well as α- and γ-classes of VchCAs and selectivity over human ubiquitous isoforms hCA I and II. Notably, all tested compounds were active inhibitors of VchCAs. The N-(4-sulfamoylbenzyl)-[1,1'-biphenyl]-4-carboxamide (20e) stood out as the most exciting inhibitor toward the β-class (K i = 95.6 nM), also showing a low affinity against the tested human isoforms. By applying docking procedures, we described the binding mode of the inhibitor 20e within the catalytic cavity of the modeled open conformation of VchCAβ.

Bioorthogonal cleavage reactions are gaining popularity in chemically inducible prodrug activation and in the control of biomolecular functions. Despite similar applications, these reactions were developed and optimized on different substrates and under different experimental conditions. Reported herein is a side-by-side comparison of palladium-, ruthenium- and tetrazine-triggered release reactions, which aims at comparing the reaction kinetics, efficiency and overall advantages and limitations of the methods. In addition, we disclose the possibility of mutual combination of the cleavage reactions. Finally, we compare the efficiency of the bioorthogonal deprotections in cellular experiments, which revealed that among the three methods investigated, the palladium- and the tetrazine-promoted reaction can be used for efficient prodrug activation, but only the tetrazine-triggered reactions proceed efficiently inside cells.