Mycobacterium Tuberculosis DprE1 Research Articles

Computational approaches to identify novel inhibitors for the drug‐ resistant Mycobacterium tuberculosis DprE1 enzyme

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.

Synthesis, Antitubercular and Antimicrobial Activity of 1,2,4‐Triazolidine‐3‐thione Functionalized Coumarin and Phenyl Derivatives and Molecular Docking Studies

AbstractTuberculosis (TB) is still a demanding worldwide health problem and mycobacterium tuberculosis (MTB) remains one of the most toxic human pathogens. In pursuit of searching new antitubercular and antimicrobial agents, substituted coumarin and phenyl‐1,2,4‐triazolidine‐3‐thiones 4a‐i and 5a‐e have been synthesized and evaluated for their antitubercular and antimicrobial activities. Most of the Substituted coumarin and phenyl‐1,2,4‐triazolidine‐3‐thiones showed promising activity against Mycobacterium tuberculosis (H37Rv). The title compounds have exhibited excellent in vitro antibacterial activity against the S.aureus, Bacillus sps and E.coli with the values of low MIC ranging from of 0.4 to 1.6 μg/mL. In vitro antifungal activity shown that the compounds 4a‐i and 5a‐e are excellent antifungal agents against Candida albicans, Aspergillus flavus, Aspergillus niger and Aspergillus fumigate fungal stains with the values of low minimum inhibitory concentrations (MIC) ranging from 0.4 to 6.25 μg/mL. Molecular docking study was performed for all the synthesized compounds with E.coli as antibacterial and Mycobacterium tuberculosis DprE1 as antituberculosis.

Design, Synthesis and Molecular Docking Studies of Novel Triazole‐Chromene Conjugates as Antitubercular, Antioxidant and Antifungal Agents

AbstractA green and efficient protocol has been developed for the synthesis of novel 1,2,3‐triazole‐chromene conjugates (7 a‐j) via ultrasound assisted and NaHCO3 catalyzed for the first time. Structures of all the new conjugates were deduced by various spectroscopic techniques. The newly synthesized triazole‐chromene conjugates were evaluated for their in vitro antitubercular activity against Mycobacterium tuberculosis (MTB) H37Rv strain. The conjugates 7 f and 7 h were found to be most active with MIC value 12.5 μg/mL. Furthermore, all the conjugates were screened for their antioxidant activity and are highly active (IC50=7.05‐14 μg/mL) than the reference drug BHT (16.47 μg/mL). The triazole‐chromene conjugates were also screened for their in vitro antifungal activity and some of the conjugates 7 a, 7 b, 7 d, 7 e, 7 f and 7 i were exhibited potent activity (MIC=6.25‐25 μg/mL) than the reference drug Miconazole. Docking studies showed significant binding affinity in the active site of Mycobacterium tuberculosis DprE1 enzyme.

Novel insight into the reaction of nitro, nitroso and hydroxylamino benzothiazinones and of benzoxacinones with Mycobacterium tuberculosis DprE1

Nitro-substituted 1,3-benzothiazinones (nitro-BTZs) are mechanism-based covalent inhibitors of Mycobacterium tuberculosis decaprenylphosphoryl-β-D-ribose-2′-oxidase (DprE1) with strong antimycobacterial properties. We prepared a number of oxidized and reduced forms of nitro-BTZs to probe the mechanism of inactivation of the enzyme and to identify opportunities for further chemistry. The kinetics of inactivation of DprE1 was examined using an enzymatic assay that monitored reaction progress up to 100 min, permitting compound ranking according to kinact/Ki values. The side-chain at the 2-position and heteroatom identity at the 1-position of the BTZs were found to be important for inhibitory activity. We obtained crystal structures with several compounds covalently bound. The data suggest that steps upstream from the covalent end-points are likely the key determinants of potency and reactivity. The results of protein mass spectrometry using a 7-chloro-nitro-BTZ suggest that nucleophilic reactions at the 7-position do not operate and support a previously proposed mechanism in which BTZ activation by a reduced flavin intermediate is required. Unexpectedly, a hydroxylamino-BTZ showed time-dependent inhibition and mass spectrometry corroborated that this hydroxylamino-BTZ is a mechanism-based suicide inhibitor of DprE1. With this BTZ derivative, we propose a new covalent mechanism of inhibition of DprE1 that takes advantage of the oxidation cycle of the enzyme.

Structural and inhibition analysis of novel sulfur-rich 2-mercaptobenzothiazole and 1,2,3-triazole ligands against Mycobacterium tuberculosis DprE1 enzyme.

Mycobacterium tuberculosis decaprenylphosphoryl-β-D-ribose oxidase (MtbDprE1) acts in concert with decaprenylphosphoryl-β-D-ribose 2-epimerase (MtbDprE2) and catalyzes the epimerization of DPR into DPA. DPA is the sole precursor for synthesis of arabinogalactan and lipoarabinomannan in the mycobacterial cell wall. MtbDprE1 is a unique antimalarial drug target and many covalent and non-covalent inhibitors against MtbDprE1 have been studied for their antituberculosis activities. In the current study, we have purified MtbDprE1 enzyme and synthesized six sulfur-rich 2-mercaptobenzothiazole and 1, 2, 3-triazole conjugated ligands and performed binding analysis with MtbDprE1. All ligands have shown competitive binding, as observed for other covalently and noncovalently bound MtbDprE1 inhibitors. Molecular docking analysis of six ligands with MtbDprE1 shows that they occupy the substrate binding pocket of MtbDprE1 and are stabilized by hydrogen bonds and van der Waals interactions. Our study shows that sulfur-rich 2-mercaptobenzothiazole ligands act as specific inhibitors against MtbDprE1 and could be used as antituberculosis agents.

DprE1, a new taxonomic marker in mycobacteria

Among the species of the Mycobacterium genus, more than 50 have been recognized as human pathogens. In spite of the different diseases caused by mycobacteria, the interspecies genetic similarity ranges from 94% to 100%, and for some species, this value is higher than in other bacteria. Consequently, it is important to understand the relationships existing among mycobacterial species. In this context, the possibility to use Mycobacterium tuberculosis dprE1 gene as new phylogenetic/taxonomic marker has been explored. The dprE1 gene codes for the target of benzothiazinones, belonging to a very promising class of antitubercular drugs. Mutations in cysteine 387 of DprE1 are responsible for benzothiazinone resistance. The DprE1 tree, obtained with 73 amino acid sequences of mycobacterial species, revealed that concerning the benzothiazinone sensitivity/resistance, it is possible to discriminate two clusters. To validate it, a concatamer obtained from the amino acid sequences of nine mycobacterial housekeeping genes was performed. The concatamer revealed that there is no separation between the benzothiazinone-susceptible and benzothiazinone-resistant species; consequently, this parameter is not linked to the phylogeny. DprE1 tree might represent a good taxonomic marker for the assignment of a mycobacterial isolate to a species. Moreover, the concatamer represents a good reference phylogeny for the Mycobacterium genus.