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Amid the global health crisis instigated by COVID-19, the resurgence of tuberculosis (TB) has underscored the urgent need for innovative solutions. With TB claiming 1.6 million lives in 2021, it remains a formidable challenge, particularly in underdeveloped regions. Central to Mycobacterium tuberculosis (Mtb) pathogenesis is the decaprenylphosphoryl-β-D-ribose oxidase (DprE1)/decaprenylphosphoryl-2-keto-β-D-erythropentose reductase (DprE2) complex, pivotal for synthesizing decaprenylphosphoryl-arabinofuranose (DPA), a critical component of mycobacterial cell walls. DprE1 has emerged as a prime therapeutic target, with several inhibitors in clinical trials. This review elucidates the indispensability of DprE1, examines existing ligands, and delineates key considerations for the development of next-generation anti-TB therapeutics. Our analysis highlights the potential of DprE1 inhibitors to revolutionize TB treatment, emphasizing the need for continued research and development in this area to address the evolving landscape of TB and drug resistance. [ABSTRACT FROM AUTHOR]

The Mycobacterium cell wall is a capsule‐like structure comprising of various layers of biomolecules such as mycolic acid, peptidoglycans, and arabinogalactans, which provide the Mycobacteria a sort of cellular shield. Drugs like isoniazid, ethambutol, cycloserine, delamanid, and pretomanid inhibit cell wall synthesis by inhibiting one or the other enzymes involved in cell wall synthesis. Many enzymes present across these layers serve as potential targets for the design and development of newer anti‐TB drugs. Some of these targets are currently being exploited as the most druggable targets like DprE1, InhA, and MmpL3. Many of the anti‐TB agents present in clinical trials inhibit cell wall synthesis. The present article covers a systematic perspective of developing cell wall inhibitors targeting various enzymes involved in cell wall biosynthesis as potential drug candidates for treating Mtb infection. [ABSTRACT FROM AUTHOR]

The rising instances of drug resistance in Mycobacterium tuberculosis strains pose a significant global health challenge. Conventional tuberculosis (TB) treatments, which typically involve multiple antibiotics, face hurdles like drug resistance, reduced effectiveness, and heightened toxicity. Consequently, there is a pressing need for innovative anti-TB agents with new modes of action. Decaprenyl-phosphoryl-β-d-ribose 2′-epimerase 1(DprE1), a crucial enzyme in Mycobacterium tuberculosis, plays a vital role in cell wall biosynthesis – a critical aspect for the bacterium’s survival. Building on the success of diarylquinolines like bedaquiline, targeting DprE1 presents a promising avenue for developing anti-TB drugs, especially against drug-resistant strains. Our research focused on discovering novel DprE1 inhibitors using a ligand-based drug design strategy, starting with the established non-covalent inhibitor Ty38c. We assembled a library of 16 molecules, modifying them based on factors like drug-like properties, chemical accessibility, and synthetic feasibility. Molecular docking analyses of this library identified three molecules with binding affinities comparable to Ty38c. Among these, KS_QD_05 and KS_QD_04 are promising candidates, which were further validated through molecular dynamics simulation studies where root-mean-square deviation (RMSD) values of all three complexes reached a plateau, measuring around 0.3 nm, indicating that the apoprotein and all complexes stabilized during the simulation. The ligands KS_QD_04 and KS_QD_05 displayed significantly stable deviation. KS_QD_05 reached about 0.1 nm equilibrium value. However, the ligand KS_QD_04 reached an RMSD value of 0.17 nm and showed distress at 70 nm. KS_QD_04 and KS_QD_05 showed an average value of 1-3 H-bond interaction and regarding the RMSF values, both the compounds showed fluctuations less than 0.5 nm in the case of Mtb. DprE1 enzyme. This indicates the potential of both compounds to become lead compounds in the pursuit of DprE1 inhibitors for TB treatment.

Amid the global health crisis instigated by COVID-19, the resurgence of tuberculosis (TB) has underscored the urgent need for innovative solutions. With TB claiming 1.6 million lives in 2021, it remains a formidable challenge, particularly in underdeveloped regions. Central to Mycobacterium tuberculosis (Mtb) pathogenesis is the decaprenylphosphoryl-β-D-ribose oxidase (DprE1)/decaprenylphosphoryl-2-keto-β-D-erythropentose reductase (DprE2) complex, pivotal for synthesizing decaprenylphosphoryl-arabinofuranose (DPA), a critical component of mycobacterial cell walls. DprE1 has emerged as a prime therapeutic target, with several inhibitors in clinical trials. This review elucidates the indispensability of DprE1, examines existing ligands, and delineates key considerations for the development of next-generation anti-TB therapeutics. Our analysis highlights the potential of DprE1 inhibitors to revolutionize TB treatment, emphasizing the need for continued research and development in this area to address the evolving landscape of TB and drug resistance.

In the quest to combat tuberculosis, DprE1, a challenging target for novel anti-tubercular agents due to its small size and membrane location, has been a focus of research. DprE1 catalyzes the transformation of DPR into Ketoribose DPX, with Benzothiazinone emerging as a potent pharmacophore for inhibiting DprE1. Clinical trial drugs such as BTZ043, BTZ038, PBTZ169, and TMC-207 have shown promising results as DprE1 inhibitors. This study employed pharmacophore mapping of Pyrazolopyridine, Dinitrobenzamide, and Benzothiazinone derivatives to identify crucial features for eliciting a biological response. Benzothiazinone (Ligand code: 73) emerged as a reference ligand with a fitness score of 3.000. ROC analysis validated the pharmacophore with an excellent score of 0.71. To build a 3D QSAR model, a series of Benzothiazinone congeneric derivatives were explored. The model exhibited strong performance, with a standard deviation of 0.1531, a correlation coefficient for the training set (R2) value of 0.9754, and a correlation coefficient for test set Q2 value of 0.7632, indicating robust predictive capabilities. Contour maps guided the design of novel benzothiazinone derivatives, emphasizing steric, electrostatic, hydrophobic, H-bond acceptor, and H-bond donor groups for structure-activity relationships. Docking studies against PDB ID: 4NCR demonstrated favorable scores, with interactions aligning well with the in-built ligand 26 J. Docking validation via RMSD values supported the reliability of the docking results. This comprehensive approach aids in the design of novel benzothiazinone derivatives with potential anti-tubercular properties, contributing to the development of novel anti-tubercular agents which can be pivotal in the eradication of tuberculosis. [ABSTRACT FROM AUTHOR]

A simple and promising methodology was employed for the synthesis of (Z)-1-(benzo[d]thiazol-2-yl)-2-(3-substituted thiazolidine-4-one) hydrazine as antitubercular agents. In vitro activity was tested against Mycobacterium tuberculosis. Two derivatives among all the synthesized compounds were found to be highly effective. Furthermore, to rationalize the observed biological activity data, a molecular docking study has also been carried out against a potential target DprE1 enzyme. The interaction was shown between the oxygen of thiazolidinediones and Ser228. The bond distance (O—H) is 2.35 Å. The π-π-stacking was seen between His137 and thiazole ring electrons. The binding score of compound 15 is –7 kcal/mol, which suggests an excellent binding affinity toward the Dpre1 receptor. [ABSTRACT FROM AUTHOR]

Abstract Decaprenylphosphoryl-β-D-ribose-2′-epimerase (DprE1), a crucial enzyme in the process of arabinogalactan and lipoarabinomannan biosynthesis, has become the target of choice for anti-TB drug discovery in the recent past. The current study aims to find the potential DprE1 inhibitors through in-silico approaches. Here, we built the pharmacophore and 3D-QSAR model using the reported 40 azaindole derivatives of DprE1 inhibitors. The best pharmacophore hypothesis (ADRRR_1) was employed for the virtual screening of the chEMBL database. To identify prospective hits, molecules with good phase scores (> 2.000) were further evaluated by molecular docking studies for their ability to bind to the DprE1 enzyme (PDB: 4KW5). Based on their binding affinities (

Tuberculosis (TB) remains a global health challenge with the emergence of drug-resistant Mycobacterium tuberculosis variants, necessitating innovative drug molecules. One potential target is the cell wall synthesis enzyme decaprenylphosphoryl-β-D-ribose 2′-epimerase (DprE1), crucial for virulence and survival. This study employed virtual screening of 111 Protein Data Bank (PDB) database molecules known for their inhibitory biological activity against DprE1 with known IC50 values. Six compounds, PubChem ID: 390820, 86287492, 155294899, 155522922, 162651615, and 162665075, exhibited promising attributes as drug candidates and validated against clinical trial inhibitors BTZ043, TBA-7371, PBTZ169, and OPC-167832. Concurrently, this research focused on DprE1 mutation effects using molecular dynamic simulations. Among the 10 mutations tested, C387N significantly influenced protein behavior, leading to structural alterations observed through root-mean-square deviation (RMSD), root-mean-square fluctuation (RMSF), radius of gyration (Rg), and solvent-accessible surface area (SASA) analysis. Ligand 2 (ID: 390820) emerged as a promising candidate through ligand-based pharmacophore analysis, displaying enhanced binding compared with reference inhibitors. Molecular dynamic simulations highlighted ligand 2's interaction with the C387N mutation, reducing fluctuations, augmenting hydrogen bonding, and influencing solvent accessibility. These collective findings emphasize ligand 2's efficacy, particularly against severe mutations, in enhancing protein-ligand complex stability. Integrated computational and pharmacophore methodologies offer valuable insights into drug candidates and their interactions within intricate protein environments. This research lays a strategic foundation for targeted interventions against drug-resistant TB, highlighting ligand 2's potential for advanced drug development strategies. [ABSTRACT FROM AUTHOR]

Decaprenylphosphoryl-β-D-ribose-2′-epimerase (DprE1), a crucial enzyme in the process of arabinogalactan and lipoarabinomannan biosynthesis, has become the target of choice for anti-TB drug discovery in the recent past. The current study aims to find the potential DprE1 inhibitors through in-silico approaches. Here, we built the pharmacophore and 3D-QSAR model using the reported 40 azaindole derivatives of DprE1 inhibitors. The best pharmacophore hypothesis (ADRRR_1) was employed for the virtual screening of the chEMBL database. To identify prospective hits, molecules with good phase scores (> 2.000) were further evaluated by molecular docking studies for their ability to bind to the DprE1 enzyme (PDB: 4KW5). Based on their binding affinities (< − 9.0 kcal/mole), the best hits were subjected to the calculation of free-binding energies (Prime/MM-GBSA), pharmacokinetic, and druglikeness evaluations. The top 10 hits retrieved from these results were selected to predict their inhibitory activities via the developed 3D-QSAR model with a regression coefficient (R2) value of 0.9608 and predictive coefficient (Q2) value of 0.7313. The induced fit docking (IFD) studies and in-silico prediction of anti-TB sensitivity for these top 10 hits were also implemented. Molecular dynamics simulations (MDS) were performed for the top 5 hit molecules for 200 ns to check the stability of the hits with DprE1. Based on their conformational stability throughout the 200 ns simulation, hit 2 (chEMBL_SDF:357100) was identified as the best hit against DprE1 with an accepted safety profile. The MD results were also in accordance with the docking score, MM-GBSA value, and 3D-QSAR predicted activity. The hit 2 molecule, (N-(3-((2-(((1r,4r)-4-(dimethylamino)cyclohexyl)amino)-9-isopropyl-9H-purin-6-yl)amino)phenyl)acrylamide) could serve as a lead for the discovery of a novel DprE1 inhibiting anti-TB drug. [ABSTRACT FROM AUTHOR]

Tuberculosis (TB) is a disease that plagues the frailest members of society. We have developed a family of N-alkyl nitrobenzamides that exhibit promising antitubercular activities and can be considered a structural simplification of known inhibitors of decaprenylphosphoryl-β-D-ribofuranose 2′-oxidase (DprE1), an essential Mycobacterium tuberculosis (Mtb) enzyme and an emergent antitubercular target. Hereby, we report the development of these compounds via a simple synthetic methodology as well as their stability, cytotoxicity, and antitubercular activity. Studying their in vitro activity revealed that the 3,5-dinitro and the 3-nitro-5-trifluoromethyl derivatives were the most active, and within these, the derivatives with intermediate lipophilicities presented the best activities (MIC of 16 ng/mL). Additionally, in an ex vivo macrophage model of infection, the derivatives with chain lengths of six and twelve carbon atoms presented the best results, exhibiting activity profiles comparable to isoniazid. Although the proof is not definite, the assessment of susceptibility over multiple mycobacterial species, together with the structure similarities with known inhibitors of this enzyme, support DprE1 as a likely target of action for the compounds. This idea is also reinforced by the docking studies, where the fit of our more active compounds to the DprE1 binding pocket is very similar to what was observed for known inhibitors like DNB1. [ABSTRACT FROM AUTHOR]

Tuberculosis (TB) continues to be a major global health challenge and a leading cause of death from infectious diseases. Inspired by the results from a previous work by our group on antimycobacterial N-alkylnitrobenzamides, which are structurally related to the nitrobenzamide family of decaprenylphosphoryl-β-d-ribose oxidase (DprE1) inhibitors, the present study explored a broad array of substituted benzamides. We particularly focused on previously unexplored 3,5-dinitrobenzamide derivatives. Starting with 3,5-dinitrobenzoic acid, we synthesized a diverse library of amides, incorporating both linear and cyclic amine moieties and also assessed the impact of terminal aromatic groups connected through ether, ester, or amide bonds on the bioactivity of the compounds. The synthesis primarily utilized nucleophilic addition/elimination, SN2, and Mitsunobu reactions. The activity was impacted mainly by two structural features, the addition of an aromatic moiety as a terminal group and the type of linker. The most interesting compounds (c2, d1, and d2, MIC = 0.031 μg/mL) exhibited activities against Mycobacterium Tuberculosis (Mtb) H37Rv comparable to isoniazid. Complementary computational studies helped elucidate potential interactions with DprE1, enhancing our understanding of the molecular basis of their action. Our findings suggest that the most active compounds provide a promising foundation for the continued development of new antimycobacterial agents. [ABSTRACT FROM AUTHOR]

Herein, we report the design of a new set of pyrazine-2-carbohydrazide derivatives (T1–T20) and in silico investigations to evaluate their inhibition activity against the enzyme, decaprenylphosphoryl- β -D-ribose 2′-epimerase (DprE1). The derivatives interact with the Cys387 residue of the enzyme's active site through hydrogen bonds. Further, we synthesized these compounds and evaluated their efficacy against the M. tuberculosis H37Rv strain. Compounds T16 and T19 displayed promising antitubercular activity, boasting a minimal inhibitory concentration of 1.56 μ g/mL. Furthermore, we assessed the antibacterial activity of these compounds against a range of pathogens, including S. aureus, S. mutans, E. coli and S. Typhi. Additionally, we evaluated their antifungal potency against A. niger. Notably, compounds T4, T8, T9, T16 and T19 exhibited noteworthy antibacterial activity against tested bacterial strains. Compounds T4, T9, T16, T17, T18 and T19 showed significant inhibition activity against A. niger. Importantly, all active compounds demonstrated low cytotoxicity, with IC50 values exceeding 300 μ M, ensuring no harm to normal cells. To gain a deeper understanding of these compounds, we conducted in silico investigations to evaluate their pharmacokinetics and pharmacochemical properties. Additionally, we employed DFT studies to explore the electronic characteristics of these compounds, providing valuable insights into their potential applications in the pharmaceutical field. A new series of pyrazine-2-carbohydrazide derivatives were synthesized. Two compounds T16 and T19 exhibited notable antitubercular activity, demonstrating a MIC of 1.56 μ g/mL. The active compounds demonstrated low toxicity, with IC 5 0 values surpassing 300 μ M and the compounds showed favorable interactions with the DprE1 enzyme in the docking studies. [ABSTRACT FROM AUTHOR]

Inhibitors of Decaprenylphosphoryl‐β‐D‐ribose 2′‐epimerase (DprE1) are being thoroughly explored as potential pharmacological entities for the development of new anti‐tubercular therapeutics. In this context, benzothiazole‐bearing compounds have emerged as potential non‐covalent DprE1 inhibitors active against mycobacterium tuberculosis. In view of the promising anti‐tubercular activity of benzothiazole based non‐covalent DprE1 inhibitor TCA1; a series of thirty small peptide conjugates of benzothiazole‐2‐carboxylic acid has been synthesized and evaluated for their anti‐tubercular activity against the M.tb H37Ra strain by broth microdilution assay. Among the compounds tested, compounds methyl (6‐methoxybenzo[d]thiazole‐2 carbonyl)tryptophylalaninate and methyl (6‐methylbenzo[d]thiazole‐2‐carbonyl)tryptophylalaninate demonstrated potential anti‐tubercular activity with minimum inhibitory concentration (MIC) values of 4 and 8 μg/mL, respectively. These compounds were further identified to be mycobactericidal and are completely killing the microbes at 8‐16 μg/mL concentrations. Furthermore, the cytotoxicity study of most potent compound methyl (6‐methoxybenzo[d]thiazole‐2 carbonyl)tryptophylalaninate illustrated no significant toxicity to the human cell line HepG2. Moreover, synthesised compounds were subject to molecular docking, ADME studies and MM‐GBSA calculations. In silico studies suggest that these compounds show strong interactions with key amino acids in the binding pocket of DprE1 (PDBID: 4KW5) with the most active conjugates residing well (with docking scores of −08.49 and −7.902 kcal/mol). [ABSTRACT FROM AUTHOR]

Mycobacterium tuberculosis causes tuberculosis (TB), which is a common but life‐debilitating disease. The continued development of resistance to frontline anti‐TB drugs such as isoniazid and rifampicin threatens the efficacy of currently available treatment procedures. This highlights the need to explore diverse approaches essential for drug development against multi‐drug‐resistant strains of tuberculosis. Drug development relies on the findings associated with novel protein targets, which play a crucial role in the disease life cycle. DprE1, an enzyme that plays a critical role in the cell wall synthesis of M. tuberculosis, has been recognized as a promising target for drug development. In the present study, based on previous experimental findings, seven mutant models of DprE1 involved in DprE1 resistance are predicted using homology modeling. Further, potential inhibitors are selected based on their efficacy and IC50 values. Shortlisted inhibitors are docked with the wild‐type and mutant structures of DprE1. The deduced inhibitor molecule (ZINC5) is found to possess high potential as a lead inhibitor for all the models of DprE1. It can be used to circumvent drug resistance in the current treatment regime.

In this study, new benzothiazole–pyrimidine hybrids (5a–c, 6, 7a–f, and 8–15) were designed and synthesised. Two different functionalities on the pyrimidine moiety of lead compound 4 were subjected to a variety of chemical changes with the goal of creating various functionalities and cyclisation to further elucidate the target structures. The potency of the new molecules was tested against different tuberculosis (TB) strains. The results indicated that compounds 5c, 5b, 12, and 15 (MIC = 0.24–0.98 µg/mL) are highly active against the first-line drug-sensitive strain of Mycobacterium tuberculosis (ATCC 25177). Thereafter, the anti-tubercular activity was evaluated against the two drug-resistant TB strains; ATCC 35822 and RCMB 2674, where, many compounds exhibited good activity with MIC = 0.98–62.5 3 µg/mL and 3.9–62.5 µg/mL, respectively. Compounds 5c and 15 having the highest anti-tubercular efficiency towards sensitive strain, displayed the best activity for the resistant strains by showing the MIC = 0.98 and 1.95 µg/mL for MDR TB, and showing the MIC = 3.9 and 7.81 µg/mL for XDR TB, consecutively. Finally, molecular docking studies were performed for the two most active compounds 5c and 15 to explore their enzymatic inhibitory activities.

Tuberculosis (TB) is a disease that plagues the frailest members of society. We have developed a family of N-alkyl nitrobenzamides that exhibit promising antitubercular activities and can be considered a structural simplification of known inhibitors of decaprenylphosphoryl-β-D-ribofuranose 2′-oxidase (DprE1), an essential Mycobacterium tuberculosis (Mtb) enzyme and an emergent antitubercular target. Hereby, we report the development of these compounds via a simple synthetic methodology as well as their stability, cytotoxicity, and antitubercular activity. Studying their in vitro activity revealed that the 3,5-dinitro and the 3-nitro-5-trifluoromethyl derivatives were the most active, and within these, the derivatives with intermediate lipophilicities presented the best activities (MIC of 16 ng/mL). Additionally, in an ex vivo macrophage model of infection, the derivatives with chain lengths of six and twelve carbon atoms presented the best results, exhibiting activity profiles comparable to isoniazid. Although the proof is not definite, the assessment of susceptibility over multiple mycobacterial species, together with the structure similarities with known inhibitors of this enzyme, support DprE1 as a likely target of action for the compounds. This idea is also reinforced by the docking studies, where the fit of our more active compounds to the DprE1 binding pocket is very similar to what was observed for known inhibitors like DNB1.

Tuberculosis (TB) continues to be a major global health challenge and a leading cause of death from infectious diseases. Inspired by the results from a previous work by our group on antimycobacterial N-alkylnitrobenzamides, which are structurally related to the nitrobenzamide family of decaprenylphosphoryl-β-d-ribose oxidase (DprE1) inhibitors, the present study explored a broad array of substituted benzamides. We particularly focused on previously unexplored 3,5-dinitrobenzamide derivatives. Starting with 3,5-dinitrobenzoic acid, we synthesized a diverse library of amides, incorporating both linear and cyclic amine moieties and also assessed the impact of terminal aromatic groups connected through ether, ester, or amide bonds on the bioactivity of the compounds. The synthesis primarily utilized nucleophilic addition/elimination, SN2, and Mitsunobu reactions. The activity was impacted mainly by two structural features, the addition of an aromatic moiety as a terminal group and the type of linker. The most interesting compounds (c2, d1, and d2, MIC = 0.031 μg/mL) exhibited activities against Mycobacterium Tuberculosis (Mtb) H37Rv comparable to isoniazid. Complementary computational studies helped elucidate potential interactions with DprE1, enhancing our understanding of the molecular basis of their action. Our findings suggest that the most active compounds provide a promising foundation for the continued development of new antimycobacterial agents.

ABSTRACT About a quarter of the world’s population is infected with Mycobacterium tuberculosis, equivalent to about two billion people. With the emergence of multidrug-resistant tuberculosis, those existing anti-tuberculosis drugs no longer meet the demand for cure anymore; there is an urgent need for the development of new anti-tuberculosis drugs. Decaprenylphosphoryl-β-D-ribose 2´-epimerase (DprE1) has been proven to be a potential antimycobacterial target, and several inhibitors have entered clinical trial. Herein, we designed and synthesized a series of compounds based on the indole and benzomorpholine by using the strategy of scaffold hopping. The preferred compound B18 showed strong antimycobacterial activity in H37Rv and drug-resistant clinical isolates. In addition, compound B18 did not exhibit antimycobacterial efficacy against other species of strains. Subsequently, the target of B18 was identified as DprE1 by analyzing spontaneous compound-resistant mutation data, and a docking study was performed to illustrate the binding mode between B18 and DprE1. In general, compound B18 is compatible to current DprE1 inhibitors, even higher phosphodiesterase 6C selectivity and plasma protein binding rate, which represent a new type of effective reversible DprE1 inhibitor. IMPORTANCE Drug therapy remains the cornerstone of tuberculosis (TB) treatment, yet first-line anti-tuberculosis drugs are associated with significant adverse effects that can compromise patient outcomes. Moreover, prolonged and widespread use has led to an alarming rise in drug-resistant strains of Mycobacterium tuberculosis, including multidrug-resistant [MDR-tuberculosis (TB)] and extensively drug-resistant (XDR-TB) forms. Urgent action is needed to develop novel anti-tuberculosis agents capable of overcoming these challenges. We report that compound B18, a decaprenylphosphoryl-β-D-ribose 2´-epimerase inhibitor with a benzomorpholine backbone, exhibits potent activity against not only the non-pathogenic strain H37Ra, but also the pathogenic strain H37Rv and clinical MDR and XDR strains. Preliminary druggability studies indicate that B18 possesses high safety and acceptable pharmacokinetic properties, rendering it a promising candidate for further development as a novel anti-tuberculosis agent.

Decaprenyl-phosphoryl-ribose 2′-epimerase (DprE1) inhibitors are an innovative and futuristic orally active group of antituberculosis agents. A few DprE1 inhibitors are in the clinical trial for tuberculosis (TB), including macozinone. This review highlights the discovery, developmental status, clinical studies, patents, and prospects of macozinone (MCZ). The patent and non-patent literature search was done by entering keywords such as macozinone; MCZ; PBTZ169; PBTZ-169 in Pubmed, Espacenet, Patentscope, and the USPTO databases. However, data on Sci-Finder was searched using CAS registry number: 1377239–83–2. MCZ clinical trial studies were retrieved from the clinicaltrials.gov database using the exact keywords. The chemical structure of MCZ was disclosed in 2009. Accordingly, patents/patent applications published from 2009 to June 12, 2022, have been discussed herein. MCZ and MCZ hydrochloride salt patents were granted in 2014 and 2019, respectively, in the USA. The patent literature and the clinical trial studies suggest capsule, tablet, and suspension formulations of crystalline MCZ and its hydrochloride salt as the possible and prospective dosage forms to treat TB. Some combinations of MCZ with other drugs (chloroquine, telacebec, tafenoquine, TBI-166, and sanfetrinem) with improved anti-TB efficacy have been documented. Based on the literature covered in this review article on the clinical studies and patents applied/granted to MCZ, it can be inferred that MCZ seems to be a promising DprE1 inhibitor and could help to tackle the emerging dilemma of drug-resistant either as a monotherapy or in combination with additional anti-TB agents. Furthermore, the authors anticipate the development of new combinations, salts, and polymorphs of MCZ as anti-TB agents shortly. This review article might prove beneficial to the scientific community as it summarizes chemistry, pharmacology and provides an update on the clinical studies and patents/patent applications of one of the emerging anti-TB drugs in one place.

Cases of drug-resistant tuberculosis (TB) have increased worldwide in the last few years, and it is a major threat to global TB control strategies and the human population. Mycobacterium tuberculosis is a common causative agent responsible for increasing cases of TB and as reported by WHO, approximately, 1.5 million death occurred from TB in 2020. Identification of new therapies against drug-resistant TB is an urgent need to be considered primarily. The current investigation aims to find the potential biogenic chalcone against the potential targets of drug-resistant TB via in silico approach. The ligand library of biogenic chalcones was screened against DprE1. Results of molecular docking and in silico ADMET prediction revealed that ZINC000005158606 has lead-like properties against the targeted protein. Pharmacophore modeling was done to identify the pharmacophoric features and their geometric distance present in ZINC000005158606. The binding stability study performed using molecular dynamics (MD) simulation of the DprE1-ZINC000005158606 complex revealed the conformational stability of the complex system over 100 ns with minimum deviation. Further, the in silico anti-TB sensitivity of ZINC000005158606 was found to be higher as compared to the standards against Mycobacterium tuberculosis. The overall in silico investigation indicated the potential of identified hit to act as a lead molecule against Mycobacterium tuberculosis. [ABSTRACT FROM AUTHOR]

The article reviews and analyzes 63 scientific publications devoted to new classes of antituberculosis drugs – DprE1 inhibitors. Currently, compounds BTZ-043, PBTZ-169 (makozinone), TBA-7371 and OPC-167832 are tested at different stages of clinical trials. DprE1 inhibitors are promising drugs with antituberculosis activity, which requires further clinical trials.

Mycobacterial infections and multidrug-resistant (MDR) strains of Mycobacterium generate high mortality, this has triggered the scientific community to search for novel, effective, and safer therapeutics. A series of 4, 5-disubstituted-1, 3, 4-oxadiazole derivatives were screened for mycobacterial activity against H37Rv, MDR and XDR strains. To recognize the mechanism of action of these compounds and to identify their supposed drug target, molecular docking and dynamics studies were employed against DprE1 mycobacterial enzyme, which is reported to be an essential enzyme for mycobacterial growth and survival. The ADME and drug-likeness properties revealed that all the compounds have good pharmacokinetic properties. All the compounds have high affinity towards the enzyme. The newly synthesized derivatives were confirmed through FT-IR, 1 H-NMR, and LCMS. In-vitro microplate alamar blue assay (MABA) to determine the MIC (minimum inhibitory concentration) values against Mycobacterium tuberculosis H37Rv was performed for the synthesized compounds. The synthesized compounds 2A, 3A, 4A, 5A and 6A exhibited promising activity against Mycobacterium tuberculosis. [ABSTRACT FROM AUTHOR]

Background: DprE1, which is a flavoenzyme, is very important for cell wall biosynthesis in Mycobacterium tuberculosis (Mtb) and for the pathogenesis, virulence, lethality, and stress resistance of the host. Drug-resistant tuberculosis is a challenging global human health issue, necessitating the development of novel, more effective treatment regimens without adverse effects. DprE1 represents a potential therapeutic target. It was explored as a drug target utilizing benzothiazoles (BTZ), which are enormously potential anti-bacterial agents and are currently being explored as anti-mycobacterial entities. Materials and Methods: We used virtual screening of bioactive molecules from PubChem and ZINC databases targeting DprE1, having bioactive thousands of molecules known for anti-microbial activity. In the present study, we selected 100 compounds as the most promising candidates to act as potential DprE1 inhibitors to control this emerging condition of tuberculosis infection. To identify the six topranked compounds, molecular docking was used to calculate the binding affinities (ranging from -8.3 to 10.0 kcal/mol) between various compounds (C1-C6) and the DprE1 protein. Results: Based on the results of an ADMET analysis, these six chemicals are safer potential drug candidates, as neither AMES toxicity nor carcinogenicity is present when toxicological properties are considered. Out of 6 compounds, the top-ranked compound exhibiting the best binding affinity against the drug target DprE1 (Pdb-id;4FEH) receptor was further subjected to molecular dynamic simulation for 100 nanoseconds to check the stability and trajectories by root-mean-square deviation (RMSD) and root-mean-square fluctuation (RMSF) graphs and interacting coordinates using Desmond Schrodinger Software. Conclusion: Our in-silico investigation identified potent inhibitors for the DprE1 protein of Mtb, and these compounds can be considered and recommended as the lead molecules in the treatment of tuberculosis. [ABSTRACT FROM AUTHOR]

Decaprenyl-phosphoryl-ribose 2′-epimerase (DprE1) inhibitors are an innovative and futuristic orally active group of antituberculosis agents. A few DprE1 inhibitors are in the clinical trial for tuberculosis (TB), including macozinone. This review highlights the discovery, developmental status, clinical studies, patents, and prospects of macozinone (MCZ). The patent and non-patent literature search was done by entering keywords such as macozinone; MCZ; PBTZ169; PBTZ-169 in Pubmed, Espacenet, Patentscope, and the USPTO databases. However, data on Sci-Finder was searched using CAS registry number: 1377239–83–2. MCZ clinical trial studies were retrieved from the clinicaltrials.gov database using the exact keywords. The chemical structure of MCZ was disclosed in 2009. Accordingly, patents/patent applications published from 2009 to June 12, 2022, have been discussed herein. MCZ and MCZ hydrochloride salt patents were granted in 2014 and 2019, respectively, in the USA. The patent literature and the clinical trial studies suggest capsule, tablet, and suspension formulations of crystalline MCZ and its hydrochloride salt as the possible and prospective dosage forms to treat TB. Some combinations of MCZ with other drugs (chloroquine, telacebec, tafenoquine, TBI-166, and sanfetrinem) with improved anti-TB efficacy have been documented. Based on the literature covered in this review article on the clinical studies and patents applied/granted to MCZ, it can be inferred that MCZ seems to be a promising DprE1 inhibitor and could help to tackle the emerging dilemma of drug-resistant either as a monotherapy or in combination with additional anti-TB agents. Furthermore, the authors anticipate the development of new combinations, salts, and polymorphs of MCZ as anti-TB agents shortly. This review article might prove beneficial to the scientific community as it summarizes chemistry, pharmacology and provides an update on the clinical studies and patents/patent applications of one of the emerging anti-TB drugs in one place. [ABSTRACT FROM AUTHOR]

Decaprenylphosphoryl-β-d-ribose-2'-epimerase (DprE1) is a druggable target which is being exploited for the development of new anti-TB agents. In the present work, we report developing a pharmacophore model and performing virtual screening of Asinex database using the developed pharmacophore model to get eight hits as potential DprE1 inhibitors. The hits were used as leads to design new 3-phenylpyrazolo[1,5- a ]pyrimidine-2,7(1 H ,4 H )-dione based potential anti-TB agents. On the basis of the identified lead molecules, a total of 18 compounds were synthesized and evaluated for their anti-TB activity by using MABA. ADMET predictions for all the compounds revealed that these compounds have drug-like and lead-like properties. One of the final compounds was found to exhibit potent anti-TB activity against Mycobacterium bovis .Communicated by Ramaswamy H. Sarma.

Benzothiazole-bearing compounds have emerged as potential noncovalent DprE1 (decaprenylphosphoryl-β-d-ribose-2'-epimerase) inhibitors active against Mycobacterium tuberculosis . Based on structure-based virtual screening (PDB ID: 4KW5), a focused library of thirty-one skeletally diverse benzothiazole amides was prepared, and the compounds were assessed for their antitubercular activity against M.tb H37Ra. Most potent compounds 3b and 3n were further evaluated against the M.tb H37Rv strain by the microdilution assay method. Among the compounds evaluated, bis - benzothiazole amide 3n emerged as a hit molecule and demonstrated promising antitubercular activity with minimum inhibitory concentration (MIC) values of 0.45 μg/mL and 8.0 μg/mL against H 37 Ra and H 37 Rv, respectively. Based on the preliminary hit molecule ( 3n) , a focused library of 12 more bis-benzothiazole amide derivatives was further prepared by varying the substituents on either side to obtain new leads and generate a structure-activity relationship (SAR). Among these compounds, 6a, 6c , and 6d demonstrated remarkable antitubercular activity with MIC values of 0.5 μg/mL against H37Ra and 1.0, 2.0, and 8.0 μg/mL against H 37 Rv, respectively. The most active compound, 6a , also displayed significant efficacy against four drug-resistant tuberculosis strains. Compound 6a was assessed for in vitro cytotoxicity against the HepG2 cell line, and it displayed insignificant cytotoxicity. Furthermore, time-kill kinetic studies demonstrated time- and dose-dependent bactericidal activity of this compound. The GFP release assay revealed that compound 6a targets the inhibition of a cell wall component. SNPs in dprE-1 gene assessment revealed that compound 6a binds to tyrosine at position 314 of DprE1 and replaces it with histidine, causing resistance similar to that of standard TCA1. In silico docking studies further suggest that the strong noncovalent interactions of these compounds may lead to the development of potent noncovalent DprE1 inhibitors.

Nitrobenzothiazinones (BTZs) are undergoing late-stage development as a novel class of potent antitubercular drug candidates with two compounds in clinical phases. BTZs inhibit decaprenylphosphoryl-β- d -ribose oxidase 1 (DprE1), a key enzyme in cell wall biosynthesis of mycobacteria. Their mechanism of action involves an in-situ -reduction of the nitro moiety to a reactive nitroso intermediate capable of covalent binding to Cys387 in the catalytic cavity. The electron-deficient nature of the aromatic core is a key driver for the formation of hydride-Meisenheimer complexes (HMC) as main metabolites in vivo. To mimic the electrophilic character of the nitroso moiety, bioisosteric replacement with different electrophilic warheads was attempted to reduce HMC formation without compromising covalent reactivity. Herein, we synthesized and characterized various covalent warheads covering different reaction principles. Covalent inhibition was confirmed for most active antimycobacterial compounds by enzymatic inhibition assays and peptide fragment analysis. [Display omitted] [ABSTRACT FROM AUTHOR]

Introduction.Tuberculosis (TB) is one of the top ten causes of death worldwide. Improvement of the treatment options via development of new drugs and treatment regimens that would be more convenient for patients is one of key options of improving the effecacy of the TB prevention and careis. Since the creation of new treatment regimens by minimizing the number of the drugs used and reducing the duration of treatment is the most promising and correct direction, macozinone, a new candidate of the benzothiazinone series, can become the basis for development of new chemotherapy regimens for drug-resistant forms of TB including the combination of macozinone with the most effective modern anti-TB drugs. Aim.Comparative evaluation of the pharmacokinetic properties of macozinone capsules 80 mg and the new dosage form a dispersible tablet for preparation of oral solution. Materials and methods.Solubility of the substance macozinone in biorelevant media in vitro, permeability of macozinone in the test Caco-2 in vitro, as well as pharmacokinetics of macozinone in dogs in vivo were evaluated. Results.The solubility assessment in biorelevant media showed that the average limit of macozinone substance dissolution in the pH 5.0 acetate buffer solution was from 6 to 9 mg/l, in FaSSIF medium (fasted) from 2.5 to 4 mg/l, and in FeSSIF medium (after meals) from 16.8 to 29 mg/l. It is established that the cell permeability of the pharmaceutical substance macozinone in the CACO-2 test system is on average 2.510-6cm/s in the forward direction from the apical to basolateral cell membrane, and 1.510-6cm/s in the reverse direction, which corresponds to low permeability. The main pharmacokinetic parameters of macozinone dispersable tablets 160 mg, after dosing with food and on an empty stomach, as well as capsules 80 mg, when administered on an empty stomach in vivo studies in dogs are presented. Discussion.The specific physicochemical properties of macozinone, the problems of developing the new dosage form, as well as ways of solving some of them are presented. Conclusion.In the process of new dosage forms development, the existing chemical properties of the macozinone substance should be considered. One of the promising ways of increasing bioavailability and, consiquently, efficacy is development a fundamentally new drug form with modified release within the absorption window.

Tuberculosis is a chronic infectious disease, usually localized in the respiratory system and representing one of the most important global social and biomedical health problems associated with the spread of therapy-resistant forms (multidrug-resistant and extensively drug-resistant tuberculosis). One of the most promising targets for the development of antimycobacterial drugs is the enzyme DprE1, which is involved in the synthesis of the cell wall of mycobacteria. In the series of DprE1 inhibitor drugs, the most advanced drug is PBTZ169 (INN maсozinone). Clinical trials (CT) of the efficacy and safety of macozinone are conducted by the pharmaceutical company LLC NEARMEDIC PLUS in the Russian Federation, and in other countries (Sponsors: Innovative Medicines for Tuberculosis Foundation, cole polytechnique fdrale de Lausanne and Bill and Melinda Gates Foundation). The publication describes results of completed I, IIa and Ib phases CT, conducted in the Russian Federation. Aim. The goal of phase I CT was to assess the safety, tolerability and pharmacokinetics (PK) of PBTZ169, 40 mg capsule, after single and multiple administration under fasting conditions in increasing doses in healthy volunteers. The goal of phase IIa CT was to study the efficacy (in terms of early bactericidal activity EBA), safety and PK of the drug PBTZ169, 80 mg capsules, in various doses, when used as monotherapy in patients with newly diagnosed respiratory tuberculosis with bacterial excretion and retained sensitivity to isoniazid and rifampicin. The purpose of phase Ib CT was to evaluate the safety, tolerability, PK of PBTZ169, 80 mg capsule, after single, double and multiple administration under fasting conditions in increasing doses, as well as the effect of food on its bioavailability in healthy volunteers. Materials and methods. The data of 100 healthy volunteers and 15 patients with newly diagnosed pulmonary tuberculosis, who received the study medication PBTZ169, capsules 40 mg and 80 mg, in the dose range 40 mg 1280 mg of PBTZ169, obtained during phase I, IIa and Ib CTs were analyzed. During I phases CTs, safety, tolerability, and PK of the drug after a single and multiple administration under fasting condition and after meals at rising doses were evaluated. The safety assessment included evaluation of AE/SAE, vital signs, ECG results, and laboratory tests results in the safety population. In the course of phase IIa CT, in addition to safety, tolerance, and PK evaluation, the efficacy of the drug (in terms of EBA) using sputum culture on agar with CFU/ml counting (main method) and quantitative PCR method (auxiliary method) was evaluated. Results. During all CTs, a high safety and tolerability profile was shown, the main PK parameters of the drug and the efficacy were described. PBTZ169 demonstrated linear PK in the dosage range up to 640 mg after single and multiple administration, a statistically significant of EBA of the drug after monotherapy at the dose of 640 mg/day was demonstrate, and it was concluded that the preferred regimen of the drug PBTZ169 intake is administration after meals. Good tolerability and a favorable safety profile of the drug in the studied doses range were demonstrate during all the CTs. Conclusion. One of the most promising and currently studied drugs-inhibitors of DprE1, a new target for the cell wall of mycobacteria, is PBTZ169 or macozinone, which is being develop by the Russian pharmaceutical company NEARMEDIC PLUS ltd.

Emerging threats of multi-drug resistant (MDR), extensively drug-resistant (XDR), and totally drug-resistant (TDR) tuberculosis led to the discovery of a novel target which was entitled Decaprenylphosphoryl-β-D-ribose 2'-epimerase (DprE1) enzyme. DprE1 is composed of two isoforms, decaprenylphosphoryl-β-D-ribose oxidase (DprE1) and decaprenylphosphoryl-D-2-keto erythro pentose reductase (DprE2). The enzymes, DprE1 and DprE2, regulate the two-step epimerization process to form DPA (Decaprenylphosphoryl arabinose) from DPX (Decaprenylphosphoryl-D-ribose), which is the sole precursor in the cell wall synthesis of arabinogalactan (AG) and lipoarabinomannan (LAM). Target-based and whole-cell-based screening played an imperative role in the identification of the druggable target, DprE1, whereas the druggability of the DprE2 enzyme is not proved yet. To date, diverse scaffolds of heterocyclic and aromatic ring systems have been reported as DprE1 inhibitors based on their interaction mode, i.e. covalent, and non-covalent inhibitors. This review describes the structure-activity relationship (SAR) of reported covalent and non-covalent inhibitors to enlighten about the crucial pharmacophoric features required for DprE1 inhibition, along with in-silico studies which characterize the amino acid residues responsible for covalent and non-covalent interactions.Communicated by Ramaswamy H. Sarma.

DprE1 inhibitors were analysed by high-throughput screening against mycobacterial cells, which produce a new class of compounds known as anti-tubercular agents. DprE1 is a fundamental mycobacterial enzyme that is responsible for the synthesis of mycobacterial cell walls. DprE1 is identified as a new target and the compounds inhibiting this target are proved to be active against such mycobacterial cells that are resistant to conventionally available marketed TB drugs. In this interest, a set of some new azo benzimidazole, prepared by condensing diazonium derivatives of benzimidazole with different suitable aromatic derivatives, were used as ligand against Mycobacterium tuberculosis DprE1 receptor. For this purpose, the crystal structure of Mycobacterium tuberculosis DprE1 in complex with the non-covalent inhibitor QN118 (PDB ID: 4P8N, 1.79 Å X-ray resolution) was retrieved from the RCSB Protein Database and used as the target. All the compounds were firmly inhibited by filling the active sites in the model with low energy values. The Present study backed that the anti-TB compounds designed by Mohanty et al. (2018) justify their in silico inhibitory property on DprE1. So, these compounds can be of clinical importance against specific diseases that may be related to the protein DprE1. [ABSTRACT FROM AUTHOR]

A very interesting foundation for this study is the creation of new methods for modifying compounds with a 1,2,3-triazole and chalcone scaffolds, as these compounds are significant in organic synthesis, particularly in the synthesis of bioactive organic compounds. To contribute to the development of an efficient method for the conversion of antimicrobial and antituberculosis heterocyclics, a novel series of cyclohepta pyridinone fused 1,2,3-triazolyl chalcones were designed and synthesized. All the newly prepared scaffolds were characterized by FT-IR, NMR ( 1 H & 13 C) and mass spectrometry. Among the tested compounds, hybrids 8b, 8d, and 8f exhibited exceptional antibacterial susceptibilities with zone of inhibition 27.84±0.04, 32.27±0.02, and 38.26±0.01 mm against the tested E. faecalis bacteria, whereas 8d had better antitubercular potency against M. tuberculosis H 37 Rv strain with MIC value 5.25 μg/mL, compared to Streptomycin [MIC=5.01 μg/mL]. All the synthesized compounds were initially assessed in silico against the targeted protein i. e., DprE1 that indicated compound 8d, 8f and 8h along with several other 1,2,3-triazole compounds as possible inhibitors. Based on docking results, 8d showed that the amino acids His 74 (A), Lys 76 (A), Cys 332 (A), Asp 331 (A), Val 307 (A), Tyr 357 (A), Met 226 (A), Gln 276 (A), Gly 75 (A), Peo 58 (A), Leu 259 (A), and Lys 309 (A) exhibited highly stable binding to DprE1 receptor of Mycobacterium tuberculosis (PDB: 4G3 U). Moreover, these scaffolds physicochemical characteristics, filtration molecular properties, assessment of toxicity, and bioactivity scores were assessed in relation to ADME (absorption, distribution, metabolism, and excretion)., (© 2024 Wiley-VHCA AG.)

Abstract Tuberculosis has proved harmful to the entire history of mankind from past several decades. Decaprenyl-phosphoryl-ribose 2′-epimerase (DprE1) is a recent target which was identified in 2009 but unfortunately it is neither explored nor crossed phase II. In past several decades few targets were identified for effective antitubercular drug discovery. Resistance is the major problem for effective antitubercular drug discovery. Arabinose is constituent of mycobacterium cell wall. Biosynthesis of arabinose is FAD dependant two step epimerisation reaction which is catalysed by DprE1 and DprE2 flavoprotein enzymes. The current review is mainly emphases on DprE1 as a perspective challenge for further research.

Benzothiazinones with 8‐NO2 group is a novel class of compounds with potent antitubercular activity, especially BTZ043 and PBTZ169, which covalently inhibit DprE1. 8‐CN benzothiazinones is reported as another type of benzothiazinones with potent antitubercular activity. Taking this as the starting point, a series of 8‐CN benzothiazinones are synthesized and evaluated for their antitubercular activity. To better understand the antitubercular activity of this series of benzothiazinones, the difference between the molecular structures of CN01 and PBTZ169 in crystal are analyzed. CN01 and PBTZ169 show completely different conformations of the piperazine ring. Density functional theory analysis (DFT) and molecular dynamics (MD) simulation are performed to provide more details to explain the different antitubercular activity. All the analysis based on crystallography, quantum chemistry, and molecular modeling lay a foundation for the subsequent structural optimization of 8‐CN benzothiazinones. [ABSTRACT FROM AUTHOR]

[Display omitted] • The design and synthesis of new indolinone-tethered benzothiophene hybrids were reported. • First, MICs were determined against the sensitive M. tuberculosis strain ATCC 25177. • The most potent compounds were furtherly assessed versus resistant MDR-TB and XDR-TB. • Validated in vivo pharmacokinetic study was performed for the most potent derivative 6 h. • Molecular docking was carried out in DprE1 active site. Joining the global effort to eradicate tuberculosis, one of the deadliest infectious killers in the world, we disclose in this paper the design and synthesis of new indolinone-tethered benzothiophene hybrids 6a-i and 7a-i as potential anti-tubercular agents. The MICs were determined in vitro for the synthesized compounds against the sensitive M. tuberculosis strain ATCC 25177. Potent compounds 6b , 6d , 6f , 6h , 7a , 7b, 7d , 7f , 7h and 7i were furtherly assessed versus resistant MDR-TB and XDR-TB. Structure activity relationship investigation of the synthesized compounds was illustrated, accordingly. Superlative potency was unveiled for compound 6h (MIC = 0.48, 1.95 and 7.81 µg/mL for ATCC 25177 sensitive TB strain, resistant MDR-TB and XDR-TB, respectively). Moreover, validated in vivo pharmacokinetic study was performed for the most potent derivative 6h revealing superior pharmacokinetic profile over the reference drug. For further exploration of the anti-tubercular mechanism of action, molecular docking was carried out for the former compound in DprE1 active site as one of the important biological targets of TB. The binding mode and the docking score uncovered exceptional binding when compared to the co-crystallized ligand suggesting that it maybe the underlying target for its outstanding anti-tubercular potency. [ABSTRACT FROM AUTHOR]

Introduction: One of the most devastating and leading diseases is Tuberculosis (TB), caused by Mycobacterium tuberculosis . Even though many synthetic drugs are available in the market, to increase the therapeutic efficacy and reduce toxicity. Isoniazid is the primary drug used in the treatment of tuberculosis., Methods: The main objective of the study is to perform molecular docking studies and synthesize the derivatives of isonicotinamide along with the anti-tubercular activity. The isonicotinamide derivatives (a-j) are prepared using isoniazid, carbon disulphate, methyl cyanide, and benzaldehyde derivatives and characterized by TLC, IR, 1 HNMR, and Mass spectroscopy. The enzyme decaprenylphosphoryl-D-ribose oxidase (DprE1) of M. tuberculosis had good binding capacity with all the ligands revealed in molecular docking studies. In-vitro studies indicated that all the ligands showed anti-tuberculosis with strain M. tuberculosis ., Results: The analysis was based on the binding energy and minimum inhibitory concentration (MIC). The highest and lowest binding energy is -4.22 Kcal/mol (f) and -8.45 Kcal/mol (d), and the MIC for compound d was found to be 644.22 nM. Among all the ligands, compound 5d has the most cytotoxic effect and lower IC 50 values and better bioavailability., Conclusion: This investigation helps in the development of better anti-tubercular therapy., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

DprE1 is involved in the synthesis of Mycobacterium tuberculosis cell wall and is a potent drug target for Tuberculosis (TB) treatment. The structure and dynamics of the loops L-I and L-II flanking the inhibitor binding site was studied using molecular dynamics (MD) simulation and MMPBSA in Amber v18. Docking and three-dimensional quantitative structure-activity relationship (3D-QSAR) of 55 Morpholino-pyrimidine (MP) inhibitors was carried out using Autodock v1.2.0 and Forge v10. ADMET analysis was done using SwissADME and pkCSM. All MP inhibitors docked in the DprE1 binding pocket, making contacts with L-II residues. MD studies showed that L-I and L-II unfold in the absence of the inhibitor but fold stably structure with reduced protein motions in the presence of MP-38, the highest affinity inhibitor. This was confirmed by k-means clustering and secondary structure analysis. L-II residues, L317, F320 and R325 contributed most towards the MMPBSA binding free energy of MP-38. A robust field-based 3D-QSAR model showed values of r 2 train = 0.982, r 2 = 0.516. The MP inhibitor field points were broadly divided into negative electrostatics near the A, B rings and hydrophobic electrostatics near the D, E rings. Addition of negative groups at methanone position and ring B as well as addition of hydrophobic and bulky groups at ring E will improve activity. Highly active compounds 47, 49 and 50 of MP series exhibited highly favourable drug-like properties. SAR and ADMET insights attained from this model will help in the development of active DprE1 inhibitors in future.Communicated by Ramaswamy H. Sarma.test = 0.702 and q 2 = 0.516. The MP inhibitor field points were broadly divided into negative electrostatics near the A, B rings and hydrophobic electrostatics near the D, E rings. Addition of negative groups at methanone position and ring B as well as addition of hydrophobic and bulky groups at ring E will improve activity. Highly active compounds 47, 49 and 50 of MP series exhibited highly favourable drug-like properties. SAR and ADMET insights attained from this model will help in the development of active DprE1 inhibitors in future.Communicated by Ramaswamy H. Sarma.

In this study, new benzothiazole-pyrimidine hybrids ( 5a - c , 6 , 7a - f , and 8 - 15 ) were designed and synthesised. Two different functionalities on the pyrimidine moiety of lead compound 4 were subjected to a variety of chemical changes with the goal of creating various functionalities and cyclisation to further elucidate the target structures. The potency of the new molecules was tested against different tuberculosis (TB) strains. The results indicated that compounds 5c , 5b , 12 , and 15 (MIC = 0.24-0.98 µg/mL) are highly active against the first-line drug-sensitive strain of Mycobacterium tuberculosis (ATCC 25177). Thereafter, the anti-tubercular activity was evaluated against the two drug-resistant TB strains; ATCC 35822 and RCMB 2674, where, many compounds exhibited good activity with MIC = 0.98-62.5 3 µg/mL and 3.9-62.5 µg/mL, respectively. Compounds 5c and 15 having the highest anti-tubercular efficiency towards sensitive strain, displayed the best activity for the resistant strains by showing the MIC = 0.98 and 1.95 µg/mL for MDR TB, and showing the MIC = 3.9 and 7.81 µg/mL for XDR TB, consecutively. Finally, molecular docking studies were performed for the two most active compounds 5c and 15 to explore their enzymatic inhibitory activities.

Graphical abstract Highlights • Compound 50 was cherry-picked from ~6.2 million compounds by virtual screening. • The anti-TB effects of compound 50 were evaluated in vivo and in vitro. • The compound 50 was confirmed no toxicity in vivo and in vitro. Abstract Despite the increasing need of new antituberculosis drugs, the number of agents approved for the market has fallen to an all-time low. In response to the emerging drug resistance followed, structurally unique chemical entities will be highlighted. decaprenylphosphoryl- β - d -ribose oxidase (DprE1) participating in the biosynthesis of mycobacterium cell wall is a highly vulnerable and validated antituberculosis target. On the basis of it, a systematic strategy was applied to identify a high-quality lead compound (compound 50) that inhibits the essential enzyme DprE1, thus blocking the synthesis of the mycobacterial cell wall to kill M. tuberculosis in vitro and in vivo. Correspondingly, the rational design and synthetic strategy for compound 50 was reported. Notably, the compound 50 has been confirmed to be no toxicity. Altogether, our data suggest the compound 50 targeting DprE1 is a promising candidate for the tuberculosis (TB) therapy. [ABSTRACT FROM AUTHOR]

Phenotypic screening of an in-house library of small molecule purine derivatives against Mycobacterium tuberculosis (Mtb) led to the identification of 2-morpholino-7-(naphthalen-2-ylmethyl)-1,7-dihydro-6 H -purin-6-one 10 as a potent antimycobacterial agent with MIC 99 of 4 μM. Thorough structure-activity relationship studies revealed the importance of 7-(naphthalen-2-ylmethyl) substitution for antimycobacterial activity, yet opened the possibility of structural modifications at positions 2 and 6 of the purine core. As the result, optimized analogues with 6-amino or ethylamino substitution 56 and 64 , respectively, were developed. These compounds showed strong in vitro antimycobacterial activity with MIC of 1 μM against Mtb H 37 Rv and against several clinically isolated drug-resistant strains, had limited toxicity to mammalian cell lines, medium clearance with respect to phase I metabolic deactivation (27 and 16.8 μL/min/mg), sufficient aqueous solubility (>90 μM) and high plasma stability. Interestingly, investigated purines, including compounds 56 and 64 , lacked activity against a panel of Gram-negative and Gram-positive bacterial strains, indicating a specific mycobacterial molecular target. To investigate the mechanism of action, Mtb mutants resistant to hit compound 10 were isolated and their genomes were sequenced. Mutations were found in dprE1 (Rv3790), which encodes decaprenylphosphoryl-β- d -ribose oxidase DprE1, enzyme essential for the biosynthesis of arabinose, a vital component of the mycobacterial cell wall. Inhibition of DprE1 by 2,6-disubstituted 7-(naphthalen-2-ylmethyl)-7 H -purines was proved using radiolabelling experiments in Mtb H 37 Rv in vitro. Finally, structure-binding relationships between selected purines and DprE1 using molecular modeling studies in tandem with molecular dynamic simulations revealed the key structural features for effective drug-target interaction. [Display omitted] • The phenotypic screening revealed antitubercular compounds in the purine family. • The initial hit 10 with MIC value of 4 μM (Mtb H 37 Rv) was optimized by SAR study. • Lead compounds showed antimycobacterial activity against drug-resistant strains. • Whole-genome sequencing and radiolabelling experiments confirmed DprE1 as a target. • The structure-binding relationship was elucidated by applying MM/MD simulations. [ABSTRACT FROM AUTHOR]

Mycobacterium tuberculos is (Mtb) has an impermeable cell wall which gives it an inherent ability to resist many antibiotics. DprE1, an essential enzyme in Mtb cell wall synthesis, has been validated as a target for several TB drug candidates. The most potent and developmentally advanced DprE1 inhibitor, PBTZ169, is still undergoing clinical development. With high attrition rate, there is need to populate the development pipeline. Using a scaffold hopping strategy, we imprinted the benzenoid ring of PBTZ169 onto a quinolone nucleus. Twenty-two compounds were synthesised and screened for activity against Mtb, with six compounds exhibiting sub micromolar activity of MIC 90 <0.244 μM. Compound 25 further demonstrated sub-micromolar activity when evaluated against wild-type and fluoroquinolone-resistant Mtb strains. This compound maintained its sub-micromolar activity against a DprE1 P116S mutant strain but showed a significant reduction in activity when tested against the DprE1 C387S mutant. [Display omitted] • Novel, easily made nitroquinolone compounds. • Exhibit sub-micromolar activity against H37Rv strain. • Exhibit sub-micromolar activity against fluoroquinolone-resistant (GyrA_G88C) strain. • Exhibit moderate metabolic stability. • MoA involves covalent inhibition of DprE1. [ABSTRACT FROM AUTHOR]

Mycobacterium tuberculosis (Mtb) has numerous cell wall and non-cell wall mediated receptors for drug action, of which cell wall mediated targets were found to be more promising because of their pivotal role in bacterial protection and survival. Herein, we reported the design and synthesis of a series of pyrazole-linked triazoles based on the reported structural features of promising drug candidates that target DprE1 receptors through a Structure-based drug design (SBDD) approach (6a-6j and 7a-7j). The synthesized compounds were evaluated for their in-vitro antitubercular activity against virulent strains of Mtb H37Rv. In-silico studies revealed that most compounds exhibit binding interactions with crucial amino acids like Lys418, Tyr314, Tyr60, and Asp386 at DprE1. Furthermore, the protein-ligand (7j) shows appreciable stability compared to innate protein in a 100 ns molecular dynamic simulation study. In-vitro MAB assay revealed that 14 compounds exhibit significant antitubercular activity with minimum inhibitory concentration (MIC) of the 3.15-4.87 μM of the 20 compounds tested. An in-vitro cytotoxicity study on normal cell lines (MCF10) revealed safe compounds (IC 50 values:341.85 to 726.08 μM). Hence, the present study opens the development of new pyrazole-linked triazoles as probable DprE1 inhibitors., (© 2023 Wiley-VHCA AG, Zurich, Switzerland.)

Benzothiazinones (BTZs) have widely inspired medicinal chemistry and translational research due to their remarkable antitubercular potency and clinical potential. While most structure-activity relationship campaigns have largely focused on lateral chain modifications and substituents on the BTZ core, scaffold hopping strategies have been rarely investigated previously. In this work, we report the first example of ring expansion of the BTZ core toward benzofuran- and naphthalene-fused thiazinones. In vitro testing showed micromolar activity for both compounds, and molecular docking simulations provided insights into their reduced inhibitory capacity toward the enzymatic target (DprE1). Calculated electrochemical potentials revealed a lower susceptibility to reduction as opposed to BTZ drug candidates, in line with the mechanistic requirement for covalent binding., (© 2023 The Authors. Archiv der Pharmazie published by Wiley-VCH GmbH on behalf of Deutsche Pharmazeutische Gesellschaft.)

Nitro-containing compounds have emerged as important agents in the control of tuberculosis (TB). From a whole-cell high-throughput screen for Mycobacterium tuberculosis (Mtb) growth inhibitors, 10 nitro-containing compounds were prioritized for characterization and mechanism of action studies. HC2209, HC2210, and HC2211 are nitrofuran-based prodrugs that need the cofactor F 420 machinery for activation. Unlike pretomanid which depends only on deazaflavin-dependent nitroreductase (Ddn), these nitrofurans depend on Ddn and possibly another F 420 -dependent reductase for activation. These nitrofurans also differ from pretomanid in their potent activity against Mycobacterium abscessus . Four dinitrobenzamides (HC2217, HC2226, HC2238, and HC2239) and a nitrofuran (HC2250) are proposed to be inhibitors of decaprenyl-phosphoryl-ribose 2'-epimerase 1 (DprE1), based on isolation of resistant mutations in dprE1 . Unlike other DprE1 inhibitors, HC2250 was found to be potent against non-replicating persistent bacteria, suggesting additional targets. Two of the compounds, HC2233 and HC2234, were found to have potent, sterilizing activity against replicating and non-replicating Mtb in vitro , but a proposed mechanism of action could not be defined. In a pilot in vivo efficacy study, HC2210 was orally bioavailable and efficacious in reducing bacterial load by ~1 log in a chronic murine TB infection model., Competing Interests: R.B.A. is the founder and owner of Tarn Biosciences, Inc., a company that is working to develop new antimycobacterial drugs.

About a quarter of the world's population is infected with Mycobacterium tuberculosis , equivalent to about two billion people. With the emergence of multidrug-resistant tuberculosis, those existing anti-tuberculosis drugs no longer meet the demand for cure anymore; there is an urgent need for the development of new anti-tuberculosis drugs. Decaprenylphosphoryl-β-D-ribose 2´-epimerase (DprE1) has been proven to be a potential antimycobacterial target, and several inhibitors have entered clinical trial. Herein, we designed and synthesized a series of compounds based on the indole and benzomorpholine by using the strategy of scaffold hopping. The preferred compound B18 showed strong antimycobacterial activity in H37Rv and drug-resistant clinical isolates. In addition, compound B18 did not exhibit antimycobacterial efficacy against other species of strains. Subsequently, the target of B18 was identified as DprE1 by analyzing spontaneous compound-resistant mutation data, and a docking study was performed to illustrate the binding mode between B18 and DprE1. In general, compound B18 is compatible to current DprE1 inhibitors, even higher phosphodiesterase 6C selectivity and plasma protein binding rate, which represent a new type of effective reversible DprE1 inhibitor. IMPORTANCE Drug therapy remains the cornerstone of tuberculosis (TB) treatment, yet first-line anti-tuberculosis drugs are associated with significant adverse effects that can compromise patient outcomes. Moreover, prolonged and widespread use has led to an alarming rise in drug-resistant strains of Mycobacterium tuberculosis , including multidrug-resistant [MDR-tuberculosis (TB)] and extensively drug-resistant (XDR-TB) forms. Urgent action is needed to develop novel anti-tuberculosis agents capable of overcoming these challenges. We report that compound B18 , a decaprenylphosphoryl-β-D-ribose 2´-epimerase inhibitor with a benzomorpholine backbone, exhibits potent activity against not only the non-pathogenic strain H37Ra, but also the pathogenic strain H37Rv and clinical MDR and XDR strains. Preliminary druggability studies indicate that B18 possesses high safety and acceptable pharmacokinetic properties, rendering it a promising candidate for further development as a novel anti-tuberculosis agent.

In this study, docking studies were performed on a series of fluoro-substituted chalcones ( E1 – E7, Z1-Z7, H1–H7 ) with DprE1 enzyme inhibition activities. The results showed that both the positions of the substituents and the type of chalcones seemed to be critical for their inhibition against DprE1. Chalcone derivatives exhibited binding affinity values of < −8.0 kcal/mol. The compounds E6 , E7 , and Z7 having a double bond in the linker group were effective inhibitors and it were found that this structural motif had an influence on the binding profile of molecules. The best docking results were detected for Z7 , which is the cis -isomer of E7 from the E group. The SAR results of the novel DprE1 inhibitors were revealed in this study and the inhibitors were predicted to have excellent potencies from the developed models. The results could greatly contribute toward designing potential new DprE1 inhibitors with better activities. [ABSTRACT FROM AUTHOR]