Click-tailed benzenesulfonamides as potent bacterial carbonic anhydrase inhibitors for targeting Mycobacterium tuberculosis and Vibrio cholerae

Antibacterial carbonic anhydrase inhibitors targeting Vibrio cholerae enzymes

INTRODUCTION

Cholera is a bacterial diarrheal disease caused by pathogen bacteria Vibrio cholerae, which produces the cholera toxin (CT). In addition to improving water sanitation, oral cholera vaccines have been developed to control infection. Besides, rehydration and antibiotic therapy are complementary treatment strategies for cholera. ToxT regulatory protein activates transcription of CT gene, which is enhanced by bicarbonate (HCO3-).

AREAS COVERED

This review delves into the genomic blueprint of V. cholerae, which encodes for α-, β-, and γ- carbonic anhydrases (CAs). We explore how the CAs contribute to the pathogenicity of V. cholerae and discuss the potential of CA inhibitors in mitigating the disease's impact.

EXPERT OPINION

CA inhibitors can reduce the virulence of bacteria and control cholera. Here, we reviewed all reported CA inhibitors, noting that α-CA from V. cholerae (VchCAα) was the most effective inhibited enzyme compared to the β- and γ-CA families (VchCAβ and VchCAγ). Among the CA inhibitors, acyl selenobenzenesulfonamidenamides and simple/heteroaromatic sulfonamides were the best VchCA inhibitors in the nM range. It was noted that some antibacterial compounds show good inhibitory effects on all three bacterial CAs. CA inhibitors belonging to other classes may be synthesized and tested on VchCAs to harness cholera.

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.

Triazole-containing hybrids with anti-Mycobacterium tuberculosis potential - Part I: 1,2,3-Triazole

Tuberculosis regimens currently applied in clinical practice require months of multidrug therapy, which imposes a major challenge of patient compliance and drug resistance development. Moreover, because of the increasing emergence of hard-to-treat tuberculosis, this disease continues to be a significant threat to the human population. 1,2,3-triazole as a privileged structure has been widely used as an effective template for drug discovery, and 1,2,3-triazole-containing hybrids that can simultaneously act on dual or multiple targets in Mycobacterium tuberculosis have the potential to circumvent drug resistance, enhance efficacy, reduce side effects and improve pharmacokinetic as well as pharmacodynamic profiles. Thus, 1,2,3-triazole-containing hybrids are useful scaffolds for the development of antitubercular agents. This review aims to highlight recent advances of 1,2,3-triazole-containing hybrids with potential activity against various forms of M. tuberculosis, covering articles published between 2015 and 2020. The structure-activity relationship and the mechanism of action are also discussed to facilitate further rational design of more effective drug candidates.

In Silico-Guided Identification of New Potent Inhibitors of Carbonic Anhydrases Expressed in Vibrio cholerae

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.

Antibacterial carbonic anhydrase inhibitors: an update on the recent literature

INTRODUCTION

The clinically licensed drugs used as antibiotics prevent the microbial growth interfering with the biosynthesis of proteins, nucleic acids, microorganism wall biosynthesis or wall permeability, and microbial metabolic pathways. A serious, emerging problem is the arisen of extensive drug resistance afflicting most countries worldwide.

AREAS COVERED

An exciting approach to fight drug resistance is the identification of essential enzymes encoded by pathogen genomes. Inhibition of such enzymes may impair microbial growth or virulence due to interference with crucial metabolic processes. Genome exploration of pathogenic and nonpathogenic microorganisms has revealed carbonic anhydrases (CAs, EC 4.2.1.1) as possible antibacterial targets.

EXPERT OPINION

Balancing the equilibrium between CO₂ and HCO₃ ^- is essential for microbial metabolism and is regulated by at least four classes of CAs. Classical CA inhibitors (CAIs) such as ethoxzolamide were shown to kill the gastric pathogen Helicobacter pylori in vitro, whereas acetazolamide and some of its more lipophilic derivatives were shown to be effective against vancomycin-resistant Enterococcus spp., with MICs in the range of 0.007-2 µg/mL, better than linezolid, the only clinically used agent available to date. Such results reinforce the rationale of considering existing and newly designed CAIs as antibacterials with an alternative mechanism of action.

Novel Indole-Based Hydrazones as Potent Inhibitors of the α-class Carbonic Anhydrase from Pathogenic Bacterium Vibrio cholerae

Due to the increasing resistance of currently used antimicrobial drugs, there is an urgent problem for the treatment of cholera disease, selective inhibition of the α-class carbonic anhydrases (CA, EC 4.2.1.1) from the pathogenic bacterium Vibrio cholerae (VcCA) presents an alternative therapeutic target. In this study, a series of hydrazone derivatives, carrying the 2-(hydrazinocarbonyl)-3-phenyl-1H-indole-5-sulfonamide scaffold, have been evaluated as inhibitors of the VcCA with molecular modeling studies. The results suggest that these compounds may bind to the active site of VcCA. To verify this, VcCA enzyme inhibition studies were performed and as predicted most of the tested compounds displayed potent inhibitory activities against VcCA with three compounds showing K_I values lower than 30 nM. In addition, all these compounds showed selectivity for VcCA and the off-targets hCA I and II.

Continued exploration and tail approach synthesis of benzenesulfonamides containing triazole and dual triazole moieties as carbonic anhydrase I, II, IV and IX inhibitors

A library of twenty two novel 1,2,3-triazole benzenesulfonamides incorporating thiosemicarbazide, 5(4H)-thione-1,2,4-triazole and variously substituted phenacyl appended 1,2,4-triazole as tail were designed, synthesized and assessed for their efficacy as inhibitors against carbonic anhydrase human (h) isoforms hCA I, II, IV and IX. The physiologically important and off-target cytosolic isoform hCA I was weakly inhibited by most of the newly synthesized sulfonamides while the glaucoma associated isoform hCA II was moderately inhibited with KIs spanning in low nanomolar range (KI = 8.0 nM-0.903 μM). The membrane bound isoform hCA IV, which is known to be involved in glaucoma and retinitis pigmentosa among others, was strongly inhibited by all newly synthesized sulfonamides out of which nine compounds inhibited isoform hCA IV even more effectively as compared to standard drug acetazolamide (AAZ). The membrane bound isoform hCA IX, associated with growth of tumor cells, was moderately inhibited with KIs ranging between 51 nM-3.198 μM. The effect of appending variously substituted tails on heterocyclic moieties over inhibition potential of synthesized sulfonamides is also disclosed which can be of further interest in pharmacological studies for exploring synthesis of isoform selective inhibitors.

Mycobacterium tuberculosis β-Carbonic Anhydrases: Novel Targets for Developing Antituberculosis Drugs

The genome of Mycobacterium tuberculosis (Mtb) encodes three β-carbonic anhydrases (CAs, EC 4.2.1.1) that are crucial for the life cycle of the bacterium. The Mtbβ-CAs have been cloned and characterized, and the catalytic activities of the enzymes have been studied. The crystal structures of two of the enzymes have been resolved. In vitro inhibition studies have been conducted using different classes of carbonic anhydrase inhibitors (CAIs). In vivo inhibition studies of pathogenic bacteria containing β-CAs showed that β-CA inhibitors effectively inhibited the growth of pathogenic bacteria. The in vitro and in vivo studies clearly demonstrated that β-CAs of not only mycobacterial species, but also other pathogenic bacteria, can be targeted for developing novel antimycobacterial agents for treating tuberculosis and other microbial infections that are resistant to existing drugs. In this review, we present the molecular and structural data on three β-CAs of Mtb that will give us better insights into the roles of these enzymes in pathogenic bacterial species. We also present data from both in vitro inhibition studies using different classes of chemical compounds and in vivo inhibition studies focusing on M. marinum, a model organism and close relative of Mtb.