Potent Antimycobacterial Activity Research Articles

Dimethyl itaconate is effective in host-directed antimicrobial responses against mycobacterial infections through multifaceted innate immune pathways

BackgroundItaconate, a crucial immunometabolite, plays a critical role in linking immune and metabolic functions to influence host defense and inflammation. Due to its polar structure, the esterified cell-permeable derivatives of itaconate are being developed to provide therapeutic opportunities in infectious and inflammatory diseases. Yet, it remains largely uncharacterized whether itaconate derivatives have potentials in promoting host-directed therapeutics (HDT) against mycobacterial infections. Here, we report dimethyl itaconate (DMI) as the promising candidate for HDT against both Mycobacterium tuberculosis (Mtb) and nontuberculous mycobacteria by orchestrating multiple innate immune programs.ResultsDMI per se has low bactericidal activity against Mtb, M. bovis Bacillus Calmette–Guérin (BCG), and M. avium (Mav). However, DMI robustly activated intracellular elimination of multiple mycobacterial strains (Mtb, BCG, Mav, and even to multidrug-resistant Mtb) in macrophages and in vivo. DMI significantly suppressed the production of interleukin-6 and -10, whereas it enhanced autophagy and phagosomal maturation, during Mtb infection. DMI-mediated autophagy partly contributed to antimicrobial host defenses in macrophages. Moreover, DMI significantly downregulated the activation of signal transducer and activator of transcription 3 signaling during infection with Mtb, BCG, and Mav.ConclusionTogether, DMI has potent anti-mycobacterial activities in macrophages and in vivo through promoting multifaceted ways for innate host defenses. DMI may bring light to new candidate for HDT against Mtb and nontuberculous mycobacteria, both of which infections are often intractable with antibiotic resistance.

Medicinal Plants as Therapeutic Alternatives to Combat Mycobacterium tuberculosis: A Comprehensive Review

Tuberculosis (TB) is a serious infectious disease caused by Mycobacterium tuberculosis (MTB) and a significant health concern worldwide. The main threat to the elimination of TB is the development of resistance by MTB to the currently used antibiotics and more extended treatment methods, which is a massive burden on the health care system. As a result, there is an urgent need to identify new, effective therapeutic strategies with fewer adverse effects. The traditional medicines found in South Asia and Africa have a reservoir of medicinal plants and plant-based compounds that are considered another reliable option for human beings to treat various diseases. Abundant research is available for the biotherapeutic potential of naturally occurring compounds in various diseases but has been lagging in the area of TB. Plant-based compounds, or phytoproducts, are being investigated as potential anti-mycobacterial agents by reducing bacterial burden or modulating the immune system, thereby minimizing adverse effects. The efficacy of these phytochemicals has been evaluated through drug delivery using nanoformulations. This review aims to emphasize the value of anti-TB compounds derived from plants and provide a summary of current research on phytochemicals with potential anti-mycobacterial activity against MTB. This article aims to inform readers about the numerous potential herbal treatment options available for combatting TB.

Histone deacetylase (HDAC) inhibitors- based drugs are effective to control Mycobacterium tuberculosis infection and promote the sensibility for rifampicin in MDR strain.

Tuberculosis (TB) is a major public health problem, which has been aggravated by the alarming growth of drug-resistant tuberculosis. Therefore, the development of a safer and more effective treatment is needed. The aim of this work was repositioning and evaluate histone deacetylases (HDAC) inhibitors- based drugs with potential antimycobacterial activity. Using an in silico pharmacological repositioning strategy, three molecules that bind to the catalytic site of histone deacetylase were selected. Pneumocytes type II and macrophages were infected with Mycobacterium tuberculosis and treated with pre-selected HDAC inhibitors (HDACi). Subsequently, the ability of each of these molecules to directly promote the elimination of M. tuberculosis was evaluated by colony-forming unit (CFU)/mL. We assessed the expression of antimicrobial peptides and respiratory burst using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Aminoacetanilide (ACE), N-Boc-1,2-phenylenediamine (N-BOC), 1,3-Diphenylurea (DFU), reduce bacillary loads in macrophages and increase the production of β-defensin-2, LL-37, superoxide dismutase (SOD) 3 and inducible nitric oxide synthase (iNOS). While only the use of ACE in type II pneumocytes decreases the bacterial load through increasing LL-37 expression. Furthermore, the use of ACE and rifampicin inhibited the survival of intracellular multi-drug resistance M. tuberculosis. Our data support the usefulness of in silico approaches for drug repositioning to provide a potential adjunctive therapy for TB.

Discovery of small molecule inhibitors of Mycobacterium tuberculosis ClpC1: SAR studies and antimycobacterial evaluation

The emergence of drug-resistant strains of Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB) in humans, is a primary reason for treatment failure. Currently, only limited options are available for the management of multi-drug resistant TB, warranting the design of novel anti-TB drugs by exploiting newer targets. One of the caseinolytic protease (Clp) machinery components, an unfoldase known as ClpC1, has emerged as a distinct anti-TB drug target owing to its essential role in the pathogen's survival. The naturally occurring cyclic peptides targeting the Mtb ClpC1, exhibit potent antimycobacterial activity. However, the large, complex, and poor synthetic tractability of these peptides limit their clinical application. Identification of small molecule inhibitors of Mtb ClpC1 will be useful for future drug development. Here, we report the discovery of a bisquinoline chemotype from the screening of a small molecule chemical library against Mtb ClpC1. The hit molecule binds with ClpC1 and exhibits dose-dependent inhibition of its enzymatic activity by direct binding. The in vitro growth of Mtb is inhibited by the hit molecule at a minimum inhibitory concentration of 12.5 µM. Investigation of the structure–activity relationship by chemical synthesis underlines the requirement of the two quinoline rings, 9/10 carbon linker, and the importance of basic ring nitrogen for its inhibitory activity. To our knowledge, this is the first report on the systematic analysis of small molecule inhibitors of Mtb ClpC1.

The Struggle to End a Millennia-Long Pandemic: Novel Candidate and Repurposed Drugs for the Treatment of Tuberculosis.

This article provides an encompassing review of the current pipeline of putative and developed treatments for tuberculosis, including multidrug-resistant strains. The review has organized each compound according to its site of activity. To provide context, mention of drugs within current recommended treatment regimens is made, thereafter followed by discussion on recently developed and upcoming molecules at established and novel targets. The review is designed to provide a clinically applicable understanding of the compounds that are deemed most currently relevant, including those already under clinical study and those that have shown promising pre-clinical results. An extensive review of the efficacy and safety data for key contemporary drugs already incorporated into treatment regimens, such as bedaquiline, pretomanid, and linezolid, is provided. The three levels of the bacterial cell wall (mycolic acid, arabinogalactan, and peptidoglycan layers) are highlighted and important compounds designed to target each layer are delineated. Amongst others, the highly optimistic and potent anti-mycobacterial activity of agents such as BTZ-043, PBTZ 169, and OPC-167832 are emphasized. The evolving spectrum of oxazolidinones, such as sutezolid, delpazolid, and TBI-223, all aiming to exceed the efficacy achieved with linezolid yet offer a safer alternative to the potential toxicity, are reviewed. New and exciting prospective agents with novel mechanisms of impact against TB, including 3-aminomethyl benzoxaboroles and telacebec, are underscored. We describe new diaryloquinolines in development, striving to build on the immense success of bedaquiline. Finally, we discuss some of these compounds that have shown encouraging additive or synergistic benefit when used in combination, providing some promise for the future in treating this ancient scourge.

2,4-Disubstituted pyridine derivatives are effective against intracellular and biofilm-forming tubercle bacilli.

It was recently reported that 4-substituted picolinohydrazonamides carrying hydrophilic cyclic amines, such as morpholine and pyrrolidine, at the end of their thiosemicarbazide chain have potent antimycobacterial activity in vitro at concentrations below 1μg/ml. Here, two selected compounds, 2,4-disubstituted pyridine derivatives 11 and 15, revealed significant bactericidal activity against Mycobacterium tuberculosis localized intracellularly within human macrophages, as well as against biofilm-forming tubercle bacilli. Mutants were selected that were resistant to the investigated compounds at an efficiency similar to that identified in the presence of the first line antituberculosis drug rifampicin. The resistant mutants were viable in the presence of the tested compounds exclusively on solid media. Genome-wide sequencing of the mutants selected in the presence of compound 11 revealed the accumulation of nonsynonymous mutations in the mmpR5 gene encoding a transcriptional repressor of the MmpS5-MmpL5 efflux pump, whose upregulation has been associated with bedaquiline resistance. The depletion of MmpR5 in wild-type M. tuberculosis using CRISPR-Cas9 technology increased the resistance of this strain to compound 11. Mass spectrometry-based proteomics (LC-MS/MS) of wild-type tubercle bacilli growing in subinhibitory concentrations of compounds 11 or 15 revealed 15 overproduced proteins not detectable in the control cells, including virulence-related proteins.

Silver nanoparticles synthesized from the seaweed Sargassum polycystum and screening for their biological potential

World-wide antimicrobial resistant is biggest threat in global health. It requires the urgent need of multisectoral action for the scientific community to achieve the sustainable development Goals. Due to their antimicrobial properties, silver nanoparticles are potential activates to pathogens, which explains their potential for multiple applications in various fields. In the present studies, we evaluate the antimicrobial properties of a Sargassum polycystum algal extract, an unrivaled green synthetic method for producing -defined shaped seaweed silver nanoparticles. To confirm their structure and size, some characterization techniques are used, such as Absorption spectrophotometer (UV–VIS), Fourier transforms infrared spectroscopy (FTIR), Scanning electron Microscope (SEM), Transmission electron microscopy (TEM) and X-Ray diffraction (XRD). Evaluate the antibacterial and anti-mycobacterial activity using silver nanoparticles. The toxicity study of this silver nanoparticle has been done with the help of zebrafish larva. The biological nanoparticle having good antimicrobial activity against Staphylococcus aureus, Micrococcus luteus, Pseudomonas fluorescens and Candida albicans and also it shows potent activity against MTB H37Rv, SHRE sensitive MTB Rifampicin resistant MTB around 98%. Seaweed nanoparticles had lower toxicity for the survival of the fish larvae. In comparison, other dosages will arrest the cell cycle and leads to death. The present finding revealed that these seaweeds nanoparticles have potential anti-mycobacterial activity against pathogens at low concentrations. This makes them a potent source of antibacterial and anti-TB agents

Identification of novel inhibitors for mycobacterial polyketide synthase 13 via in silico drug screening assisted by the parallel compound screening with genetic algorithm-based programs.

Identifying small compounds capable of inhibiting Mycobacterium tuberculosis polyketide synthase 13 (Pks13), in charge of final step of mycolic acid biosynthesis, could lead to the development of a novel antituberculosis drug. This study screened for lead compounds capable of targeting M. tuberculosis Pks13 from a chemical library comprising 154,118 compounds through multiple in silico docking simulations. The parallel compound screening (PCS), conducted via two genetic algorithm-based programs was applied in the screening strategy. Out of seven experimentally validated compounds, four compounds showed inhibitory effects on the growth of the model mycobacteria (Mycobacterium smegmatis). Subsequent docking simulation of analogs of the promising leads with the assistance of PCS resulted in the identification of three additional compounds with potent antimycobacterial effects (compounds A1, A2, and A5). Further, molecular dynamics simulation predicted stable interaction between M. tuberculosis Pks13 active site and compound A2, which showed potent antimycobacterial activity comparable to that of isoniazid. The present study demonstrated the efficacy of in silico structure-based drug screening through PCS in antituberculosis drug discovery.

Nano-Based Drug Delivery Systems of Potent MmpL3 Inhibitors for Tuberculosis Treatment.

Tuberculosis remains one of the world’s deadliest infectious diseases, accounting for nearly 1.3 million deaths every year. Tuberculosis treatment is challenging because of the toxicity, decreased bioavailability at the target site of the conventional drugs and, most importantly, low adherence of patients; this leads to drug resistance. Here, we describe the development of suitable nanocarriers with specific physicochemical properties to efficiently deliver two potent antimycobacterial compounds. We prepared nanoemulsions and niosomes formulations and loaded them with two different MmpL3 inhibitors previously identified (NEs + BM635 and NIs + BM859). NEs + BM635 and NIs + BM859 were deeply characterized for their physicochemical properties and anti-mycobacterial activity. NEs + BM635 and NIs + BM859 showed good hydrodynamic diameter, ζ-Potential, PDI, drug-entrapment efficiency, polarity, and microviscosity and stability. Even though both formulations proved to perform well, only NIs + BM859 showed potent antimycobacterial activity against M. tuberculosis (MIC = 0.6 µM) compared to that of the free compound. This is most probably caused by the fact that BM635, being highly hydrophobic, encounters maximum hindrance in diffusion, whereas BM859, characterized by high solubility in aqueous medium (152 µM), diffuses more easily. The niosomal formulation described in this work may be a useful therapeutic tool for tuberculosis treatment, and further studies will follow to characterize the in vivo behavior of the formulation.

Tachyplesin and CyLoP-1 as efficient anti-mycobacterial peptides: A novel finding

Mycobacterium tuberculosis is an etiological agent of tuberculosis (TB) known to be a highly contagious disease and is the major cause of mortality from a single infectious agent worldwide. Emergence of multi-drug resistant and extremely drug resistant strains of M. tuberculosis has made TB management extremely challenging eliciting the urgent need for alternative therapeutics. Peptide based therapeutic strategies are an emerging area that can be employed as a prospective alternative to the currently existing therapeutic regime for TB treatment. Here, we are reporting the anti-mycobacterial activity of two peptides, Tachyplesin and CyLoP-1, derived from marine horseshoe crab and snake toxin respectively, with potent anti-mycobacterial activity against various mycobacterium species. Both the peptides exhibit appreciable antimicrobial and anti-biofilm activities against mycobacterium species with minimum cytotoxicity towards macrophage cells. They are also effective in eliminating mycobacterium cells from infected macrophage cells. Tachyplesin acts on mycobacterium cells in a lytic manner with outer membrane disruption confirmed by propidium iodide uptake with slight membrane depolarization and reactive oxygen species (ROS) production. CyLoP-1, on the other hand, does not rupture the mycobacterium cells even at high concentrations. It seems to follow intracellular pathway of killing mycobacterium cells by production of more ROS and membrane depolarization. Both the peptides do not lead to apoptotic way of mycobacterium cell death. These results suggest an effective peptide-based antimicrobial strategy for development of future anti-TB therapeutics.

Characterization of Pyridomycin B Reveals the Formation of Functional Groups in Antimycobacterial Pyridomycin.

Pyridomycin, a cyclodepsipeptide with potent antimycobacterial activity, specifically inhibits the InhA enoyl reductase of Mycobacterium tuberculosis. Structure-activity relationship studies indicated that the enolic acid moiety in the pyridomycin core system is an important pharmacophoric group, and the natural configuration of the C-10 hydroxyl contributes to the bioactivity of pyridomycin. The ring structure of pyridomycin was generated by the nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) hybrid system (PyrE-PyrF-PyrG). Bioinformatics analysis reveals that short-chain dehydrogenase/reductase (SDR) family protein Pyr2 functions as a 3-oxoacyl acyl carrier protein (ACP) reductase in the pyridomycin pathway. Inactivation of pyr2 resulted in accumulation of pyridomycin B, a new pyridomycin analogue featured with enol moiety in pyridyl alanine moiety and a saturated 3-methylvaleric acid group. The elucidated structure of pyridomycin B suggests that rather than functioning as a post-tailoring enzyme, Pyr2 catalyzes ketoreduction to form the C-10 hydroxyl group in pyridyl alanine moiety and the double bond formation of the enolic acid moiety derived from isoleucine when the intermediate assembled by PKS-NRPS machinery is still tethered to the last NRPS module in a special energy-saving manner. Ser-His-Lys residues constitute the active site of Pyr2, which is different from the typically conserved Tyr-based catalytic triad in the majority of SDRs. Site-directed mutation identified that His154 in the active site is a critical residue for pyridomycin B production. These findings will improve our understanding of pyridomycin biosynthetic logic, identify the missing link for the double bound formation of enol ester in pyridomycin, and enable the creation of chemical diversity of pyridomycin derivatives. IMPORTANCE Tuberculosis (TB) is one of the world's leading causes of death by infection. Recently, pyridomycin, the antituberculous natural product from Streptomyces has garnered considerable attention for being determined as a target inhibitor of InhA enoyl reductase of Mycobacterium tuberculosis. In this study, we report a new pyridomycin analogue from mutant HTT12, demonstrate the essential role of a previously ignored gene pyr2 in pyridomycin biosynthetic pathway, and imply that Pyr2 functions as a trans ketoreductase (KR) contributing to the formation of functional groups of pyridomycin utilizing a distinct catalytic mechanism. As enol moiety are important for pharmaceutical activities of pyridomycin, our work would expand our understanding of the mechanism of SDR family proteins and set the stage for future bioengineering of new pyridomycin derivatives.

Phytochemical, Cytotoxicity, and Antimycobacterial Activity Evaluation of Extracts and Compounds from the Stem Bark of Albizia coriaria Welw ex. Oliver.

Background Albizia coriaria Welw ex. Oliver (Fabaceae) is one of the plants used by herbalists in the East Africa community to prepare herbal remedies for the management of symptoms of TB. Despite its widespread use, the antimycobacterial activity of this plant was uninvestigated and there was contradicting information regarding its cytotoxicity. Methods Cytotoxicity (MTT), antimycobacterial activity (MABA), and phytochemical screening were conducted on crude extracts (hexane, chloroform, acetone, and methanol) of the stem bark of A. coriaria. Gas chromatography-mass spectrometry (GC-MS) followed by Fourier transform infrared (FTIR) spectroscopy was carried out on the acetone and methanol extracts. The binding affinities and descriptors of pharmacokinetics and toxicity of the identified compounds were predicted using computational modelling software. Results The cytotoxic concentrations of all extracts were greater than 1000 μg/mL. The minimum inhibitory concentration of both the acetone and methanol extracts was 1250.0 ± 0.0 μg/mL against M. smegmatis, whereas that against M. tuberculosis was 937.0 ± 442.0 μg/mL and 2500.0 ± 0.0 μg/mL, respectively. Hexane and chloroform extracts were not active against both strains. Alkaloids, triterpenes, flavonoids, tannins, and saponins were the predominant phytochemicals present. GC-MS analysis revealed twenty-eight and nineteen compounds in acetone and methanol extracts, respectively. Among these was hydroquinone, which was previously reported to possess antimycobacterial activity. Seven compounds identified through GC-MS analysis had better binding affinities for the mycobacterial ATPase and polyketide synthase-13 than isoniazid and rifampicin. These compounds also showed variable but promising pharmacokinetic properties with minimum toxicity. Conclusion There are phytochemicals in A. coriaria stem bark with potential antimycobacterial activity and acceptable cytotoxicity, which can be further explored and optimized for the development of novel antitubercular drugs.

Identification of thiophene-benzenesulfonamide derivatives for the treatment of multidrug-resistant tuberculosis

A series of thiophene-benzenesulfonamide derivatives was designed and synthesized by exploring the structure-activity relationship of lead compounds 2,3-disubstituted thiophenes 25a and 297F as antituberculosis agents, which displayed potent antimycobacterial activity against drug-susceptible and clinically isolated drug-resistant tuberculosis. In particular, compound 17b, which had improved activity (minimum inhibitory concentration of 0.023 μg/mL) compared with the lead compounds, displayed good intracellular antimycobacterial activity in macrophages with a reduction of 1.29 log10 CFU. A druggability evaluation indicated that compound 17b had favorable hepatocyte stability, low cytotoxicity, and low hERG channel inhibition. Moreover, compound 17b exhibited modest in vivo efficacy in an acute mouse model of tuberculosis. In addition, the molecular docking study elucidated the binding mode of compound 17b in the active site of DprE1. Therefore, compound 17b may be a promising antituberculosis lead for further research.

Discovery of novel nitrogenous heterocyclic-containing quinoxaline-1,4-di-N-oxides as potent activator of autophagy in M.tb-infected macrophages.

As a continuation of our research on antimycobacterial agents, a series of novel quinoxaline-1,4-di-N-oxides (QdNOs) containing various nitrogenous heterocyclic moieties at the R6 position were designed and synthesized. Antimycobacterial activities, as well as the cytotoxic effects, of the compounds were assayed. Four compounds (6b, 6f, 6n, and 6o), characterized by 2-carboxylate ethyl or benzyl ester, 6-imidazolyl or 1,2,4-triazolyl, and a 7-fluorine group, exhibited the most potent antimycobacterial activity against M.tb strain H37Rv (MIC≤0.25μg/mL) with low toxicity in VERO cells (SI=169.3-412.1). Compound 6o also exhibited excellent antimycobacterial activity in an M.tb-infected macrophage model and was selected for further exploration of the mode of antimycobacterial action of QdNOs. The results showed that compound 6o was capable of disrupting membrane integrity and disturbing energy homeostasis in M.tb. Furthermore, compound 6o noticeably increased cellular ROS levels and, subsequently, induced autophagy in M.tb-infected macrophages, possibly indicating the pathways of QdNOs-mediated inhibition of intracellular M.tb replication. The invivo pharmacokinetic (PK) profiles indicated that compounds 6o was acceptably safe and possesses favorable PK properties. Altogether, these findings suggest that compound 6o is a promising antimycobacterial candidate for further research.

Voatriafricanines A and B, Trimeric Vobasine-Aspidosperma-Aspidosperma Alkaloids from Voacanga africana.

Voatriafricanines A and B (1 and 2), the first examples of vobasine-aspidosperma-aspidosperma monoterpene trisindole alkaloids, were isolated from the stem barks of Voacanga africana, guided by a molecular networking strategy. Their structures, including absolute configurations, were elucidated by spectroscopic methods and ECD calculations. Compounds 1 and 2 possess intramolecular hydrogen bonding, sufficiently robust to transfer homonuclear and heteronuclear magnetizations. Compound 1 exhibited potent antimycobacterial activity with no discernible cytotoxic activity.

Quinoxaline Moiety: A Potential Scaffold against Mycobacterium tuberculosis.

Background. The past decades have seen numerous efforts to develop new antitubercular agents. Currently, the available regimens are lengthy, only partially effective, and associated with high rates of adverse events. The challenge is therefore to develop new agents with faster and more efficient action. The versatile quinoxaline ring possesses a broad spectrum of pharmacological activities, ensuring considerable attention to it in the field of medicinal chemistry. Objectives. In continuation of our program on the pharmacological activity of quinoxaline derivatives, this review focuses on potential antimycobacterial activity of recent quinoxaline derivatives and discusses their structure—activity relationship for designing new analogs with improved activity. Methods. The review compiles recent studies published between January 2011 and April 2021. Results. The final total of 23 studies were examined. Conclusions. Data from studies of quinoxaline and quinoxaline 1,4-di-N-oxide derivatives highlight that specific derivatives show encouraging perspectives in the treatment of Mycobacterium tuberculosis and the recent growing interest for these scaffolds. These interesting results warrant further investigation, which may allow identification of novel antitubercular candidates based on this scaffold.

Mycobacterium tuberculosis RpfE-Induced Prostaglandin E2 in Dendritic Cells Induces Th1/Th17 Cell Differentiation.

Prostaglandin E2 (PGE2) is an important biological mediator involved in the defense against Mycobacterium tuberculosis (Mtb) infection. Currently, there are no reports on the mycobacterial components that regulate PGE2 production. Previously, we have reported that RpfE-treated dendritic cells (DCs) effectively expanded the Th1 and Th17 cell responses simultaneously; however, the mechanism underlying Th1 and Th17 cell differentiation is unclear. Here, we show that PGE2 produced by RpfE-activated DCs via the MAPK and cyclooxygenase 2 signaling pathways induces Th1 and Th17 cell responses mainly via the EP4 receptor. Furthermore, mice administered intranasally with PGE2 displayed RpfE-induced antigen-specific Th1 and Th17 responses with a significant reduction in bacterial load in the lungs. Furthermore, the addition of optimal PGE2 amount to IL-2-IL-6-IL-23p19-IL-1β was essential for promoting differentiation into Th1/Th17 cells with strong bactericidal activity. These results suggest that RpfE-matured DCs produce PGE2 that induces Th1 and Th17 cell differentiation with potent anti-mycobacterial activity.

Four-Month Rifapentine Regimens with or without Moxifloxacin for Tuberculosis

BackgroundRifapentine-based regimens have potent antimycobacterial activity that may allow for a shorter course in patients with drug-susceptible pulmonary tuberculosis.MethodsIn an open-label, phase 3, randomized, controlled trial involving persons with newly diagnosed pulmonary tuberculosis from 13 countries, we compared two 4-month rifapentine-based regimens with a standard 6-month regimen consisting of rifampin, isoniazid, pyrazinamide, and ethambutol (control) using a noninferiority margin of 6.6 percentage points. In one 4-month regimen, rifampin was replaced with rifapentine; in the other, rifampin was replaced with rifapentine and ethambutol with moxifloxacin. The primary efficacy outcome was survival free of tuberculosis at 12 months.ResultsAmong 2516 participants who had undergone randomization, 2343 had a culture positive for Mycobacterium tuberculosis that was not resistant to isoniazid, rifampin, or fluoroquinolones (microbiologically eligible population; 768 in the control group, 791 in the rifapentine–moxifloxacin group, and 784 in the rifapentine group), of whom 194 were coinfected with human immunodeficiency virus and 1703 had cavitation on chest radiography. A total of 2234 participants could be assessed for the primary outcome (assessable population; 726 in the control group, 756 in the rifapentine–moxifloxacin group, and 752 in the rifapentine group). Rifapentine with moxifloxacin was noninferior to the control in the microbiologically eligible population (15.5% vs. 14.6% had an unfavorable outcome; difference, 1.0 percentage point; 95% confidence interval [CI], −2.6 to 4.5) and in the assessable population (11.6% vs. 9.6%; difference, 2.0 percentage points; 95% CI, −1.1 to 5.1). Noninferiority was shown in the secondary and sensitivity analyses. Rifapentine without moxifloxacin was not shown to be noninferior to the control in either population (17.7% vs. 14.6% with an unfavorable outcome in the microbiologically eligible population; difference, 3.0 percentage points [95% CI, −0.6 to 6.6]; and 14.2% vs. 9.6% in the assessable population; difference, 4.4 percentage points [95% CI, 1.2 to 7.7]). Adverse events of grade 3 or higher occurred during the on-treatment period in 19.3% of participants in the control group, 18.8% in the rifapentine–moxifloxacin group, and 14.3% in the rifapentine group.ConclusionsThe efficacy of a 4-month rifapentine-based regimen containing moxifloxacin was noninferior to the standard 6-month regimen in the treatment of tuberculosis. (Funded by the Centers for Disease Control and Prevention and others; Study 31/A5349 ClinicalTrials.gov number, NCT02410772.)

Discovery of Novel Thiophene-arylamide Derivatives as DprE1 Inhibitors with Potent Antimycobacterial Activities.

In this study, we report the design and synthesis of a series of novel thiophene-arylamide compounds derived from the noncovalent decaprenylphosphoryl-β-d-ribose 2′-epimerase (DprE1) inhibitor TCA1 through a structure-based scaffold hopping strategy. Systematic optimization of the two side chains flanking the thiophene core led to new lead compounds bearing a thiophene-arylamide scaffold with potent antimycobacterial activity and low cytotoxicity. Compounds 23j, 24f, 25a, and 25b exhibited potent in vitro activity against both drug-susceptible (minimum inhibitory concentration (MIC) = 0.02–0.12 μg/mL) and drug-resistant (MIC = 0.031–0.24 μg/mL) tuberculosis strains while retaining potent DprE1 inhibition (half maximal inhibitory concentration (IC50) = 0.2–0.9 μg/mL) and good intracellular antimycobacterial activity. In addition, these compounds showed good hepatocyte stability and low inhibition of the human ether-à-go-go related gene (hERG) channel. The representative compound 25a with acceptable pharmacokinetic property demonstrated significant bactericidal activity in an acute mouse model of tuberculosis. Moreover, the molecular docking study of template compound 23j provides new insight into the discovery of novel antitubercular agents targeting DprE1.

Development and Validation of a Liquid Chromatographic Method for Aroylhydrazones at Hydrolytic Conditions

Background: The indole-containing aroylhydrazone derivatives 3a-c with potent antimycobacterial activity against a referent strain M. tuberculosis H37Rv and low cytotoxicity were evaluated for their stability via the precise and accurate HPLC analytical method in aqueous media of different pH (2.0, 7.0, 9.0 and 12.0). Objective: The study describes the development and validation of a simple and reliable HPLC-UV procedure for the determination of aroylhydrazone derivatives and their hydrolytic stability. Additionally, to recognize if hydrolysis leads to generating undesired products, the degradation processes were identified. Method: The separation was achieved with a LiChrosorb®RP-18 (250 x 4.6 mm) column, at ambient temperature with isocratic mode with mobile phase containing mixture of component A (acetonitrile) and component B (0.001M NaH2PO4, with 5 mM 1-heptane sulfonic acid sodium salt, adjusted to pH 3.0) in a ratio 60:40 (v/v). The flow rate was 1.0 ml/min and the eluent was monitored at 297 nm. The proposed method was validated as per ICH guidelines. Result: The obtained results showed that the compounds were sensitive to hydrolytic decomposition in aqueous media, resulting in the splitting of the hydrazone bond. Rapid hydrolysis of substances was observed in the acid medium. The elevated temperature significantly accelerated the hydrolytic reaction. Relatively slow hydrolysis of 3a-c was observed in a neutral solution and aqueous solutions buffered to pH 9. The hydrolysis of 3a-c in neutral, alkaline and strong alkaline medium followed the pseudo- first-order reaction rate and showed a linear dependence of lnC versus time. Conclusion: A validated high-performance liquid chromatographic assay for the determination of the hydrolytic stability of a series of aroylhydrazones was developed and optimized for the first time. The methods devised are successfully applicable to the development of pharmaceutical formulations.