Evaluation of Thio- and Seleno-Acetamides Bearing Benzenesulfonamide as Inhibitor of Carbonic Anhydrases from Different Pathogenic Bacteria

Recent developments of agents targeting Vibrio cholerae: patents and literature data

INTRODUCTION

Vibrio cholerae bacteria cause an infection characterized by acute diarrheal illness in the intestine. Cholera is sustained by people swallowing contaminated food or water. Even though symptoms can be mild, if untreated disease becomes severe and life-threatening, especially in low-income countries.

AREAS COVERED

After a description of the most recent literature on the pathophysiology of this infection, we searched for patents and literature articles following the PRISMA guidelines, filtering the results disclosed from 2020 to present. Moreover, some innovative molecular targets (e.g., carbonic anhydrases) and pathways to counteract this rising problem were also discussed in terms of design, structure-activity relationships and structural analyses.

EXPERT OPINION

This review aims to cover and analyze the most recent advances on the new druggable targets and bioactive compounds against this fastidious pathogen, overcoming the use of old antibiotics which currently suffer from high resistance rate.

Synthesis, Biological and In Silico Studies of Griseofulvin and Usnic Acid Sulfonamide Derivatives as Fungal, Bacterial and Human Carbonic Anhydrase Inhibitors

Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the essential reaction of CO₂ hydration in all living organisms, being actively involved in the regulation of a plethora of patho-/physiological conditions. A series of griseofulvin and usnic acid sulfonamides were synthesized and tested as possible CA inhibitors. Since β- and γ- classes are expressed in microorganisms in addition to the α- class, showing substantial structural differences to the human isoforms they are also interesting as new antiinfective targets with a different mechanism of action for fighting the emerging problem of extensive drug resistance afflicting most countries worldwide. Griseofulvin and usnic acid sulfonamides were synthesized using methods of organic chemistry. Their inhibitory activity, assessed against the cytosolic human isoforms hCA I and hCA II, the transmembrane hCA IX as well as β- and γ-CAs from different bacterial and fungal strains, was evaluated by a stopped-flow CO₂ hydrase assay. Several of the investigated derivatives showed interesting inhibition activity towards the cytosolic associate isoforms hCA I and hCA II, as well as the three γ-CAs and Malassezia globosa (MgCA) enzyme. Six compounds (1b-1d, 1h, 1i and 1j) were more potent than AAZ against hCA I while five (1d, 1h, 1i, 1j and 4a) showed better activity than AAZ against the hCA II isoform. Moreover, all compounds appeared to be very potent against MgCA with a Ki lower than that of the reference drug. Furthermore, computational procedures were used to investigate the binding mode of this class of compounds within the active site of human CAs.

Enhancing the Activity of Carboxymethyl Cellulase Enzyme Using Highly Stable Selenium Nanoparticles Biosynthesized by Bacillus paralicheniformis Y4

The inorganic selenium is absorbed and utilized inefficiently, and the range between toxicity and demand is narrow, so the application is strictly limited. Selenium nanoparticles have higher bioactivity and biosafety properties, including increased antioxidant and anticancer properties. Thus, producing and applying eco-friendly, non-toxic selenium nanoparticles in feed additives is crucial. Bacillus paralicheniformis Y4 was investigated for its potential ability to produce selenium nanoparticles and the activity of carboxymethyl cellulases. The selenium nanoparticles were characterized using zeta potential analyses, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). Additionally, evaluations of the anti-α-glucosidase activity and the antioxidant activity of the selenium nanoparticles and the ethyl acetate extracts of Y4 were conducted. B. paralicheniformis Y4 exhibited high selenite tolerance of 400 mM and the selenium nanoparticles had an average particle size of 80 nm with a zeta potential value of −35.8 mV at a pH of 7.0, suggesting that the particles are relatively stable against aggregation. After 72 h of incubation with 5 mM selenite, B. paralicheniformis Y4 was able to reduce it by 76.4%, yielding red spherical bio-derived selenium nanoparticles and increasing the carboxymethyl cellulase activity by 1.49 times to 8.96 U/mL. For the first time, this study reports that the carboxymethyl cellulase activity of Bacillus paralicheniforis was greatly enhanced by selenite. The results also indicated that B. paralicheniformis Y4 could be capable of ecologically removing selenite from contaminated sites and has great potential for producing selenium nanoparticles as feed additives to enhance the added value of agricultural products.

Biochemical, structural, and computational studies of a γ-carbonic anhydrase from the pathogenic bacterium Burkholderia pseudomallei

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Melioidosis is a severe disease caused Burkholderia pseudomallei.

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γ-carbonic anhydrases (γ-CAs) have been recently introduced as novel antibacterial drug targets.

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A new γ-CA from B. pseudomallei has been investigated by a multidisciplinary approach.

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Obtained results provide an important starting point for developing new anti-melioidosis drugs.

Melioidosis is a severe disease caused by the highly pathogenic gram-negative bacterium Burkholderia pseudomallei. Several studies have highlighted the broad resistance of this pathogen to many antibiotics and pointed out the pivotal importance of improving the pharmacological arsenal against it. Since γ-carbonic anhydrases (γ-CAs) have been recently introduced as potential and novel antibacterial drug targets, in this paper, we report a detailed characterization of BpsγCA, a γ-CA from B. pseudomallei by a multidisciplinary approach. In particular, the enzyme was recombinantly produced and biochemically characterized. Its catalytic activity at different pH values was measured, the crystal structure was determined and theoretical pKa calculations were carried out. Results provided a snapshot of the enzyme active site and dissected the role of residues involved in the catalytic mechanism and ligand recognition. These findings are an important starting point for developing new anti-melioidosis drugs targeting BpsγCA.

Synthesis and biological evaluation of sulfonamide-based compounds as inhibitors of carbonic anhydrase from Vibrio cholerae

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 K_i 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.

Pyrazolo[4,3-c]pyridine Sulfonamides as Carbonic Anhydrase Inhibitors: Synthesis, Biological and In Silico Studies

Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the essential reaction of CO₂ hydration in all living organisms, being actively involved in the regulation of a plethora of patho-/physiological conditions. A series of chromene-based sulfonamides were synthesized and tested as possible CA inhibitors. On the other hand, in microorganisms, the β- and γ- classes are expressed in addition to the α- class, showing substantial structural differences to the human isoforms. In this scenario, not only human but also bacterial CAs are of particular interest as new antibacterial agents with an alternative mechanism of action for fighting the emerging problem of extensive drug resistance afflicting most countries worldwide. Pyrazolo[4,3-c]pyridine sulfonamides were synthesized using methods of organic chemistry. Their inhibitory activity, assessed against the cytosolic human isoforms hCA I and hCA II, the transmembrane hCA IX and XII, and β- and γ-CAs from three different bacterial strains, was evaluated by a stopped-flow CO₂ hydrase assay. Several of the investigated derivatives showed interesting inhibition activity towards the cytosolic associate isoforms hCA I and hCA II, as well as the 3β- and 3γ-CAs. Furthermore, computational procedures were used to investigate the binding mode of this class of compounds within the active site of hCA IX. Four compounds (1f, 1g, 1h and 1k) were more potent than AAZ against hCA I. Furthermore, compound 1f also showed better activity than AAZ against the hCA II isoform. Moreover, ten compounds out of eleven appeared to be very potent against the γ-CA from E.coli, with a Ki much lower than that of the reference drug. Most of the compounds showed better activity than AAZ against hCA I as well as the γ-CA from E.coli and the β-CA from Burkholderia pseudomallei (BpsCAβ). Compounds 1f and 1k showed a good selectivity index against hCA I and hCA XII, while 1b was selective against all 3β-CA isoforms from E.coli, BpsCA, and VhCA and all 3γ-CA isoforms from E.coli, BpsCA and PgiCA.

Synthesis and Evaluation of Antioxidant, Anti-Edematogenic and Antinociceptive Properties of Selenium-Sulfa Compounds

Herein we describe results for the synthesis and synthetic application of 4-amino-3-(arylselenyl)benzenesulfonamides, and preliminary evaluation of antioxidant, anti-edematogenic and antinociceptive properties. This class of compounds was synthesized in good yields by a reaction of commercially available sulfanilamide and diorganyl diselenides in the presence of 10 mol% of I2 . Furthermore, the synthesized compound 4-amino-3-(phenylselenyl)benzenesulfonamide (3 a) was evaluated on complete Freund's adjuvant (CFA)-induced acute inflammatory pain. Dose- and time-response curves of antinociceptive effect of compound 3 a were performed using this experimental model. Also, the effect of compound 3 a was monitored in a hot-plate test to evaluate the acute non-inflammatory antinociception. The open-field test was performed to evaluate the locomotor and exploratory behaviors of mice. Oxidative stress markers, such as glutathione peroxidase activity; reactive species, non-protein thiols, and lipid peroxidation levels were performed to investigate the antioxidant action of compound 3 a. Our findings suggest that the antioxidant effect of compound 3 a may contribute to reducing the nociception and suppress the signaling pathways of inflammation on the local injury induced by CFA. Thus, compound 3 a reduced the paw edema as well as the hyperalgesic behavior in mice, being a promising therapeutic agent for the treatment of painful conditions.

The Role of Selenium in Pathologies: An Updated Review

Selenium is an essential microelement required for a number of biological functions. Selenium—and more specifically the amino acid selenocysteine—is present in at least 25 human selenoproteins involved in a wide variety of essential biological functions, ranging from the regulation of reactive oxygen species (ROS) concentration to the biosynthesis of hormones. These processes also play a central role in preventing and modulating the clinical outcome of several diseases, including cancer, diabetes, Alzheimer’s disease, mental disorders, cardiovascular disorders, fertility impairments, inflammation, and infections (including SARS-CoV-2). Over the past years, a number of studies focusing on the relationship between selenium and such pathologies have been reported. Generally, an adequate selenium nutritional state—and in some cases selenium supplementation—have been related to improved prognostic outcome and reduced risk of developing several diseases. On the other hand, supra-nutritional levels might have adverse effects. The results of recent studies focusing on these topics are summarized and discussed in this review, with particular emphasis on advances achieved in the last decade.

Novel 1,3,5-Triazinyl Aminobenzenesulfonamides Incorporating Aminoalcohol, Aminochalcone and Aminostilbene Structural Motifs as Potent Anti-VRE Agents, and Carbonic Anhydrases I, II, VII, IX, and XII Inhibitors

A series of 1,3,5-triazinyl aminobenzenesulfonamides substituted by aminoalcohol, aminostilbene, and aminochalcone structural motifs was synthesized as potential human carbonic anhydrase (hCA) inhibitors. The compounds were evaluated on their inhibition of tumor-associated hCA IX and hCA XII, hCA VII isoenzyme present in the brain, and physiologically important hCA I and hCA II. While the test compounds had only a negligible effect on physiologically important isoenzymes, many of the studied compounds significantly affected the hCA IX isoenzyme. Several compounds showed activity against hCA XII; (E)-4-{2-[(4-[(2,3-dihydroxypropyl)amino]-6-[(4-styrylphenyl)amino]-1,3,5-triazin-2-yl)amino]ethyl}benzenesulfonamide (31) and (E)-4-{2-[(4-[(4-hydroxyphenyl)amino]-6-[(4-styrylphenyl)amino]-1,3,5-triazin-2-yl)amino]ethyl}benzenesulfonamide (32) were the most effective inhibitors with K_Is = 4.4 and 5.9 nM, respectively. In addition, the compounds were tested against vancomycin-resistant Enterococcus faecalis (VRE) isolates. (E)-4-[2-({4-[(4-cinnamoylphenyl)amino]-6-[(4-hydroxyphenyl)amino]-1,3,5-triazin-2-yl}amino)ethyl]benzenesulfonamide (21) (MIC = 26.33 µM) and derivative 32 (MIC range 13.80-55.20 µM) demonstrated the highest activity against all tested strains. The most active compounds were evaluated for their cytotoxicity against the Human Colorectal Tumor Cell Line (HCT116 p53 +/+). Only 4,4'-[(6-chloro-1,3,5-triazin-2,4-diyl)bis(iminomethylene)]dibenzenesulfonamide (7) and compound 32 demonstrated an IC₅₀ of ca. 6.5 μM; otherwise, the other selected derivatives did not show toxicity at concentrations up to 50 µM. The molecular modeling and docking of active compounds into various hCA isoenzymes, including bacterial carbonic anhydrase, specifically α-CA present in VRE, was performed to try to outline a possible mechanism of selective anti-VRE activity.

Bis-triazolylchalcogenium-Functionalized Benzothiadiazole Derivatives as Light-up Sensors for DNA and BSA

A range of bis-triazolylchalcogenium-BTD 3 was synthesized by a copper-catalyzed azide-alkyne cycloaddition of azido arylchalcogenides 1 and 4,7-diethynylbenzo[c][1,2,5]thiadiazole 2. Eight new compounds were obtained in moderate to good yields using 1 mol % of copper(II) acetate monohydrate under mild reaction conditions. In addition, the synthesized bis-triazolylchalcogenium-BTD 3a-3h were investigated regarding their photophysical, electrochemical, and biomolecule binding properties in solution. In general, compounds presented strong absorption bands at the 250-450 nm region and cyan to green emission properties. The redox process attributed to the chalcogen atom was observed by electrochemical analysis (CV techniques). In addition, spectroscopic studies by UV-vis, steady-state emission fluorescence, and molecular docking calculations evidenced the ability of each derivative to establish interactions with calf-thymus DNA (CT-DNA) and bovine serum albumin (BSA). The behavior presented for this new class of compounds makes them a promising tool as optical sensors for biomolecules.

Novel insights on saccharin- and acesulfame-based carbonic anhydrase inhibitors: design, synthesis, modelling investigations and biological activity evaluation

A large library of saccharin and acesulfame derivatives has been synthesised and evaluated against four isoforms of human carbonic anhydrase, the two off-targets hCA I/II and the tumour related isoforms hCA IX/XII. Different strategies of scaffold modification have been attempted on both saccharin as well as acesulfame core leading to the obtainment of 60 compounds. Some of them exhibited inhibitory activity in the nanomolar range, albeit some of the performed changes led to either micromolar activity or to its absence, against hCA IX/XII. Molecular modelling studies focused the attention on the binding mode of these compounds to the enzyme. The proposed inhibition mechanism is the anchoring to zinc-bound water molecule. Docking studies along with molecular dynamics also underlined the importance of the compounds flexibility (e.g. achieved through the insertion of methylene group) which favoured potent and selective hCA inhibition.

Carbonic Anhydrases: Versatile and Useful Biocatalysts in Chemistry and Biochemistry

Metalloenzymes such as the carbonic anhydrases (CAs, EC 4.2.1.1) possess highly specialized active sites that promote fast reaction rates and high substrate selectivity for the physiologic reaction that they catalyze, hydration of CO2 to bicarbonate and a proton. Among the eight genetic CA macrofamilies, α-CAs possess rather spacious active sites and show catalytic promiscuity, being esterases with many types of esters, but also acting on diverse small molecules such as cyanamide, carbonyl sulfide (COS), CS2, etc. Although artificial CAs have been developed with the intent to efficiently catalyse non-biologically related chemical transformations with high control of stereoselectivity, the activities of these enzymes were much lower when compared to natural CAs. Here, we report an overview on the catalytic activities of α-CAs as well as of enzymes which were mutated or artificially designed by incorporation of transition metal ions. In particular, the distinct catalytic mechanisms of the reductase, oxidase and metatheses-ase such as de novo designed CAs are discussed.

Sweet Selenium: Synthesis and Properties of Selenium-Containing Sugars and Derivatives

In the last decades, organoselenium compounds gained interest due to their important biological features. However, the lack of solubility, which characterizes most of them, makes their actual clinical exploitability a hard to reach goal. Selenosugars, with their intrinsic polarity, do not suffer from this issue and as a result, they can be conceived as a useful alternative. The aim of this review is to provide basic knowledge of the synthetic aspects of selenosugars, selenonium salts, selenoglycosides, and selenonucleotides. Their biological properties will be briefly detailed. Of course, it will not be a comprehensive dissertation but an analysis of what the authors think is the cream of the crop of this interesting research topic.