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Tuberculosis is one of the most common causes of death worldwide, with a rapid emergence of multi-drug-resistant strains underscoring the need for new antituberculosis drugs. Recent studies indicate that lansoprazole-a known gastric proton pump inhibitor and its intracellular metabolite, lansoprazole sulfide (LPZS)-are potential antituberculosis compounds. Yet, their inhibitory mechanism and site of action still remain unknown. Here, we combine biochemical, computational, and structural approaches to probe the interaction of LPZS with the respiratory chain supercomplex III 2 IV 2 of Mycobacterium smegmatis , a close homolog of Mycobacterium tuberculosis supercomplex. We show that LPZS binds to the Q o cavity of the mycobacterial supercomplex, inhibiting the quinol substrate oxidation process and the activity of the enzyme. We solve high-resolution (2.6 Å) cryo-electron microscopy (cryo-EM) structures of the supercomplex with bound LPZS that together with microsecond molecular dynamics simulations, directed mutagenesis, and functional assays reveal key interactions that stabilize the inhibitor, but also how mutations can lead to the emergence of drug resistance. Our combined findings reveal an inhibitory mechanism of LPZS and provide a structural basis for drug development against tuberculosis., Competing Interests: Competing interests statement:The authors declare no competing interest.

Tuberculosis (TB) continues to be a major global health burden, with high incidence and mortality rates, compounded by the emergence and spread of drug-resistant strains. The limitations of current TB medications and the urgent need for new drugs targeting drug-resistant strains, particularly multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB, underscore the pressing demand for innovative anti-TB drugs that can shorten treatment duration. This has led to a focus on targeting energy metabolism of Mycobacterium tuberculosis (Mtb) as a promising approach for drug discovery. This study focused on repurposing drugs against the crucial mycobacterial protein, electron transfer flavoprotein oxidoreductase (EtfD), integral to utilizing fatty acids and cholesterol as a carbon source during infection. The research adopted an integrative approach, starting with virtual screening of approved drugs from the ZINC20 database against EtfD, followed by molecular docking, and concluding with molecular dynamics (MD) simulations. Diacerein, levonadifloxacin, and gatifloxacin were identified as promising candidates for repurposing against TB based on their strong binding affinity, stability, and interactions with EtfD. ADMET analysis and anti-TB sensitivity predictions assessed their pharmacokinetic and therapeutic potential. Diacerein and levonadifloxacin, previously unexplored in anti-tuberculous therapy, along with gatifloxacin, known for its efficacy in drug-resistant TB, have broad-spectrum antimicrobial properties and favorable pharmacokinetic profiles, suggesting potential as alternatives to current TB treatments, especially against resistant strains. This study underscores the efficacy of computational drug repurposing, highlighting bacterial energy metabolism and lipid catabolism as fruitful targets. Further research is necessary to validate the clinical suitability and efficacy of diacerein, levonadifloxacin, and gatifloxacin, potentially enhancing the arsenal against global TB., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Arshad et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Mycobacterium tuberculosis (Mtb), the pathogen responsible for tuberculosis (TB), is the leading cause of bacterial disease-related death worldwide. Current antibiotic regimens for the treatment of TB remain dated and suffer from long treatment times as well as the development of drug resistance. As such, the search for novel chemical modalities that have selective or potent anti-Mtb properties remains an urgent priority, particularly against multidrug-resistant (MDR) Mtb strains. Herein, we design and synthesize 35 novel b enzo[c] p henanthridine d erivatives (BPDs). The two most potent compounds, BPD-6 and BPD-9, accumulated within the bacterial cell and exhibited strong inhibitory activity (MIC 90 ~2 to 10 µM) against multiple Mycobacterium strains while remaining inactive against a range of other Gram-negative and Gram-positive bacteria. BPD-6 and BPD-9 were also effective in reducing Mtb survival within infected macrophages, and BPD-9 reduced the burden of Mycobacterium bovis BCG in the lungs of infected mice. The two BPD compounds displayed comparable efficacy to rifampicin (RIF) against non-replicating Mtb (NR-Mtb). Importantly, BPD-6 and BPD-9 inhibited the growth of multiple MDR Mtb clinical isolates. Generation of BPD-9-resistant mutants identified the involvement of the Mmr efflux pump as an indirect resistance mechanism. The unique specificity of BPDs to Mycobacterium spp. and their efficacy against MDR Mtb isolates suggest a potential novel mechanism of action. The discovery of BPDs provides novel chemical scaffolds for anti-TB drug discovery.IMPORTANCEThe emergence of drug-resistant tuberculosis (TB) is a serious global health threat. There remains an urgent need to discover new antibiotics with unique mechanisms of action that are effective against drug-resistant Mycobacterium tuberculosis (Mtb). This study shows that novel semi-synthetic compounds can be derived from natural compounds to produce potent activity against Mtb. Importantly, the identified compounds have narrow spectrum activity against Mycobacterium species, including clinical multidrug-resistant (MDR) strains, are effective in infected macrophages and against non-replicating Mtb (NR-Mtb), and show anti-mycobacterial activity in mice. These new compounds provide promising chemical scaffolds to develop potent anti-Mtb drugs of the future., Competing Interests: The authors declare no conflict of interest.

A library of 25-series compounds was designed against Mycobacterium Tuberculosis (M.tb) to identify novel antitubercular drugs. In silico inhibition of InhA, an essential component of FAS-II, was successfully achieved. The drug ability, lead-likeness, and toxicity of the compounds were assessed using Swiss ADME, pkCSM, and Osiris Property Explorer, which revealed the potential for drug development of chalcone compounds. Through in silico research, it was confirmed that toxic-free compounds could bind to InhA. It was found that all of the compounds bind to InhA with binding affinities ranging from -7.78 to -10.29 kcal/mol -1 which is higher than the reference standard Isoniazid and Pyrazinamide. The top five compounds were synthesized from 15 toxic-free compounds. The structural characteristics of the compounds were determined using IR, NMR, and mass spectrometry techniques. These findings indicate that these substances are competitive, reversible, and specific InhA inhibitors of InhA. using the Alamar Blue assay method (H37RV, ATCC No. 27294), the in vitro anti-mycobacterial activity of each of the synthesized compounds against M.tb was evaluated. The two most powerful compounds were (2E)-3-[4-(benzyloxy)-3,5-dimethylphenyl] and (2E)-1-(3,5-dibromophenyl)-3-(3-phenoxyphenyl) prop-2-en-1-one. In the MABA Assay, the MIC for 1-(3,5-dibromophenyl) prop-2-en-1-one was 6.25 μg/ml., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In previous studies, we demonstrated the potent activity of a library of 25 N,N'-disubstituted diamines (NNDDA) toward Trypanosomatid and Apicomplexa parasites. Considering the structure similarity between this collection and SQ109, an antituberculosis compound, and its compelling antiparasitic properties, we aimed to repurpose this library for tuberculosis treatment. We assayed this collection against Mycobacterium tuberculosis H37Rv and M. avium, obtaining several compounds with MIC values below 10 µM. The most active analogs were also evaluated against M. smegmatis, a non-pathogenic species, and the non-tuberculosis mycobacteria M. abscessus, M. kansasii, and M. fortuitum. 3c stands out as the lead mycobacterial compound of the collection, with potent activity against M. tuberculosis (minimal inhibitory concentration [MIC] = 3.4 µM) and moderate activity against M. smegmatis, M. kansasii, and M. fortuitum (all with MIC values of 26.8 µM). To unravel the mechanism of action, we employed the web-based platform Polypharmacology Browser 2 (PPB2), obtaining carbonic anhydrases as potential drug targets. Nevertheless, none of the compounds displayed experimental inhibition. In summary, our study confirms the validity of the repurposing approach and underscores the antimycobacterial potential of NNDDA compounds, especially the analog 3c, setting a stepping stone for further studies., (© 2024 Deutsche Pharmazeutische Gesellschaft.)

Spectinamides are a novel class of narrow-spectrum antitubercular agents with the potential to treat drug-resistant tuberculosis infections. Spectinamide 1810 has shown a good safety record following subcutaneous injection in mice or infusion in rats but exhibits transient acute toxicity following bolus administration in either species. To improve the therapeutic index of 1810, an injectable prodrug strategy was explored. The injectable phosphate prodrug 3408 has a superior maximum tolerated dose compared to 1810 or Gentamicin. Following intravenous administration in rodents, prodrug 3408 was quickly converted to 1810. The resulting 1810 exposure and pharmacokinetic profile after 3408 administration was identical to equivalent molar amounts of 1810 given directly by intravenous administration. 3408 and the parent 1810 exhibited similar overall efficacy in a BALB/c acute tuberculosis efficacy model. Delivery of 1810 in phosphate prodrug form, therefore, holds the potential to improve further the therapeutic index of an already promising tuberculosis antibiotic., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: RL, JL, and BM disclose intellectual property rights associated with spectinamide series., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), continues to pose a significant global health threat. Identifying new druggable targets is crucial for the advancement of drug development. Equally critical is the development of precise methods for monitoring Mtb to effectively combat this disease. Addressing these needs, our study pinpointed the pore domain (PD) of MtbMmpL3 as a new binding site for virtual screening, which led to the discovery of the small molecule ZY27. To confirm the binding site and action mode of ZY27, we employed cosolvent molecular dynamics (CMD), steered molecular dynamics (SMD), and long timescale molecular dynamics (MD) simulations of 5 μs. These in silico studies verified that ZY27 binds to the PD of MtbMmpL3. In antimicrobial activity tests, ZY27 exhibited potent anti-Mtb activity and high selectivity among mycobacterial species. Whole-genome sequencing of spontaneous ZY27-resistant Mtb variants, complemented by acid-fast staining experiments, confirmed that ZY27 specifically targets MtbMmpL3. Utilizing the ligand-protein binding data, we designed and synthesized two solvatochromic fluorescent probes, 27FP1 and 27FP2, based on ZY27. Further investigations through flow cytometry and confocal microscopy confirmed that these probes specifically label Mtb cells via the MtbMmpL3 binding mechanism., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The rise of drug-resistant Mycobacterium tuberculosis (Mtb) has extended the duration of tuberculosis (TB) treatment and reduced the likelihood of cure. One strategy to combat this issue is the development of inhibitors targeting the virulence factors of bacterial pathogens. Mtb' catalase (KatG) is crucial for its detoxification mechanisms and also serves as a significant virulence factor for the bacterium. In this study, twelve derivatives synthesized from 5-fluoropyridine and benzo[b]thiophene demonstrated antimycobacterial efficacy with minimum inhibitory concentrations (MICs) varying between 0.5 and 32 μg/mL. Compound 2, 1-(benzo[b]thiophen-2-ylmethylene) thiosemicarbazide, emerged as the most potent candidate. It effectively inhibited Mtb KatG, enhanced the production of reactive oxygen species (ROS) in Mtb, and achieved Mtb killing within 96 hours at a concentration of 2 μg/mL (4×MIC). Molecular docking simulations revealed that compound 2 binds tightly to the active site of Mtb-KatG with a docking score of 114, indicating that it may serve as a potent inhibitor of Mtb-KatG. The rabbit skin tuberculosis model was employed to assess the virulence of Mtb. Animal study results indicated that the granulomas induced by Mtb after treatment with compound 2 were reduced in size, exhibited a lower bacterial load, and the bacteria were no longer aggregated, in contrast to those caused by untreated Mtb. Hence, compound 2 can be regarded as a molecule capable of neutralizing the virulence factors of Mtb. This research offers insights into the design of anti-Mtb molecules with novel mechanisms of action., (© 2024 Wiley-VHCA AG, Zurich, Switzerland.)

In the chronicles of human history, infectious diseases played a pivotal role, influencing societies, steering advancements in medicine, and significantly impacting the well-being of people worldwide. Consequently, in the pursuit of identifying effective combating agents for infectious ailments, the Co(II), Ni(II), Cu(II), Zn(II) complexes of N'-(4-nitrobenzylidene)benzohydrazide were synthesized in the current investigation. Numerous spectral and physical analysis were conducted to characterize the compounds which revealed octahedral stereochemistry of complexes. The anti-tuberculosis, anti-inflammatory, antibacterial and antifungal investigations demonstrated that the compounds (1-5) have significant efficacy for these infectious ailments. The [Zn(L) 2 (H 2 O) 2 ] complex (5) has comparable TB inhibition potency to streptomycin as shown by MIC value of 0.0196±0.0003 μmol/mL. Additionally, the anti-inflammatory, antibacterial and antifungal studies also revealed the comparable inhibiting property of (5) to standard drugs with significant IC 50 (07.49±0.08 μM) and MIC (0.0098 μmol/mL) values. Furthermore, pharmacophore modeling with addition of molecular docking, DFT, MESP, ADMET were employed against compounds (1-5) to give a new insight in biological evaluations. The pharmacophore modeling suggested that (5) has a distinctive pharmacophoric features including cationic sites, hydrogen-bond donors and acceptors which provide valuable insights into rational drug design for specific pharmacological applications. Moreover, another in silico investigations authenticate the bioactivity of (5) through substantial binding affinities, binding energy, stability, hardness, electrophilicity etc. Overall, the combined computational and experimental results highlight the potential of [Zn(L) 2 (H 2 O) 2 ] as a promising candidate for tuberculosis treatment, meriting further in vivo investigations., (© 2024 Wiley-VHCA AG, Zurich, Switzerland.)

Generative drug design facilitates the creation of compounds effective against pathogenic target proteins. This opens up the potential to discover novel compounds within the vast chemical space and fosters the development of innovative therapeutic strategies. However, the practicality of generated molecules is often limited, as many designs focus on a narrow set of drug-related properties, failing to improve the success rate of subsequent drug discovery process. To overcome these challenges, we develop TamGen, a method that employs a GPT-like chemical language model and enables target-aware molecule generation and compound refinement. We demonstrate that the compounds generated by TamGen have improved molecular quality and viability. Additionally, we have integrated TamGen into a drug discovery pipeline and identified 14 compounds showing compelling inhibitory activity against the Tuberculosis ClpP protease, with the most effective compound exhibiting a half maximal inhibitory concentration (IC 50 ) of 1.9 μM. Our findings underscore the practical potential and real-world applicability of generative drug design approaches, paving the way for future advancements in the field., (© 2024. The Author(s).)

Multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) continue as public health concerns. Inhaled drug therapy for TB has substantial benefits in combating the causal agent of TB (Mycobacterium tuberculosis). Pretomanid is a promising candidate in an optional combined regimen for XDR-TB. Pretomanid has demonstrated high potency against M. tuberculosis in both the active and latent phases. Conventional spray drying was used to formulate pretomanid as dry powder inhalers (DPIs) for deep lung delivery using a proliposomal system with a trehalose coarse excipient to enhance the drug solubility. Co-spray drying with L-leucine protected hygroscopic trehalose in formulations and improved powder aerosolization. Higher amounts of L-leucine (40-50 % w/w) resulted in the formation of mesoporous particles with high percentages of drug content and entrapment efficiency. The aerosolized powders demonstrated both geometric and median aerodynamic diameters < 5 µm with > 90 % emitted dose and > 50 % fine particle fraction. Upon reconstitution in simulated physiological fluid, the proliposomes completely converted to liposomes, exhibiting suitable particle sizes (130-300 nm) with stable colloids and improving drug solubility, leading to higher drug dissolution compared to the drug alone. Inhalable pretomanid showed higher antimycobacterial activity than pretomanid alone. The formulations were safe for all broncho-epithelial cell lines and alveolar macrophages, thus indicating their potential suitability for DPIs targeting pulmonary TB., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Tuberculosis remains a leading cause of death from a single infection worldwide. Drug resistance to existing and even new antimycobacterials calls for research into novel targets and unexplored mechanisms of action. Recently we reported on the development of tight-binding inhibitors of Mycobacterium tuberculosis (Mtb) lipoamide dehydrogenase (Lpd), which selectively inhibit the bacterial but not the human enzyme based on a differential modality of inhibitor interaction with these targets. Here we report on the striking improvement in inhibitor residence time on the Mtb enzyme associated with scaffold progression from an indazole to 2-cyanoindole. Cryo-EM of Lpd with the bound 2-cyanoindole inhibitor 19 confirmed displacement of the buried water molecule deep in the binding channel with a cyano group. The ensuing hours-long improvement in on-target residence time is associated with enhanced antibacterial activity in axenic culture and in primary mouse macrophages. Resistance to 2-cyanoindole inhibitors involves mutations within the inhibitor binding site that have little effect on inhibitor affinity but change the modality of inhibitor-target interaction, resulting in fast dissociation from Lpd. These findings underscore that on-target residence time is a major determinant of antibacterial activity and in vivo efficacy., (© 2024 Wiley-VCH GmbH.)

Tuberculosis (TB) is a global health concern caused by the bacterium Mycobacterium tuberculosis. This infectious disease primarily affects the lungs but can also impact other organs. Effective TB control involves early diagnosis, appropriate treatment with a combination of antibiotics, and public health measures to prevent transmission. However, ongoing challenges include drug-resistant strains and socioeconomic factors influencing its prevalence. Drugs such as isoniazid, pyrazinamide, ethambutol, ethionamide, linezolid, and levofloxacin are approved for the treatment of drug-susceptible tuberculosis. The properties and other activities of the drug, can be analyzed by modelling its chemical structure in terms of a molecular graph [Formula: see text], by considering the atoms as the vertex set [Formula: see text] and the bonds between the two atoms as the edge set [Formula: see text]. A molecular descriptor or topological index of [Formula: see text] represents the corresponding chemical molecule as a numerical value. Domination is one of the key concepts in the molecular structure used to analyze the properties of atoms. In this article, the domination distance-based topological indices of the drugs isoniazid, pyrazinamide, ethambutol, ethionamide, linezolid, and levofloxacin are computed to conduct QSPR (Quantitative Structure-Property Relationship) analysis, exploring their physicochemical and ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) properties. Quadratic regression is then used in the QSPR analysis to examine the physicochemical and ADMET properties of these drugs. The results of this analysis indicate that the domination Schultz index and domination SM index are the indices most strongly correlated with the majority of the physicochemical and ADMET properties. The QSPR analysis can also be extended to analogs of these drugs and to other treatment drugs, such as rifampin and rifapentine, to further explore their properties., (© 2024. The Author(s).)

Spread of antimicrobial resistances urges a need for new drugs against Mycobacterium tuberculosis (Mtb) with mechanisms differing from current antibiotics. Previously, callyaerins were identified as promising anti-tubercular agents, representing a class of hydrophobic cyclopeptides with an unusual (Z)-2,3-di-aminoacrylamide unit. Here, we investigated the molecular mechanisms underlying their antimycobacterial properties. Structure-activity relationship studies enabled the identification of structural determinants relevant for antibacterial activity. Callyaerins are bacteriostatics selectively active against Mtb, including extensively drug-resistant strains, with minimal cytotoxicity against human cells and promising intracellular activity. By combining mutant screens and various chemical proteomics approaches, we showed that callyaerins target the non-essential, Mtb-specific membrane protein Rv2113, triggering a complex dysregulation of the proteome, characterized by global downregulation of lipid biosynthesis, cell division, DNA repair, and replication. Our study thus identifies Rv2113 as a previously undescribed Mtb-specific drug target and demonstrates that also non-essential proteins may represent efficacious targets for antimycobacterial drugs., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The nonproton pumping type II NADH dehydrogenase in Mycobacterium tuberculosis is essential for meeting the energy needs in terms of ATP under normal aerobic and stressful hypoxic environmental states. Type II NADH dehydrogenase conduits electrons into the electron transport chain in Mycobacterium tuberculosis , which results in ATP synthesis. Therefore, the inhibition of NDH-2 ensures the abolishment of the entire ATP synthesis machinery. Also, type II NADH dehydrogenase is absent in the mammalian genome, thus making it a potential target for antituberculosis drug discovery. Herein, we have screened a commercially available library of drug-like molecules and have identified a hit having a benzimidazole core moiety ( 6 , H37Rv mc 2 6230; minimum inhibitory concentration (MIC) = 16 μg/mL and ATP IC 50 = 0.23 μg/mL) interfering with the oxidative phosphorylation pathway. Extensive medicinal chemistry optimization resulted in analogue 8, with MIC = 4 μg/mL and ATP IC 50 = 0.05 μg/mL against the H37Rv mc 2 6230 strain of Mycobacterium tuberculosis . Compounds 6 and 8 were found to be active against mono- and multidrug-resistant mycobacterium strains and demonstrated a bactericidal response. The Peredox-mCherry experiment and identification of single-nucleotide polymorphisms in mutants of CBR-5992 (a known type II NADH dehydrogenase inhibitor) were used to confirm the molecules as inhibitors of the type II NADH dehydrogenase enzyme. The safety index >10 for the test active molecules revealed the safety of test molecules.

New drugs and mechanisms of action targeting Mycobacterium tuberculosis are urgently needed to solve the global pandemic of tuberculosis. We previously demonstrated that the 8-hydroxyquinoline series has rapid bactericidal activity against M. tuberculosis . In this work, we determined that the activity of the 8HQ series is potentiated by copper ions and that the activity is dependent on copper since activity was reduced when copper was depleted from the medium. We determined that exposure to 8HQs led to an increase in intracellular copper. The increase in copper ions was specific since we saw no changes for other metal cations (zinc, iron, magnesium, manganese, or calcium). We observed the transient generation of reactive oxygen species after 8HQ exposure which disappeared by 24 h. Inhibition of growth could be partially relieved by scavenging hydroxyl radicals. We excluded the possibility that 8HQs are toxic by DNA intercalation. We screened a panel of hypomorph strains and identified sensitized strains. The pattern of sensitized strains did not suggest a specific target, but metalloenzymes, proteins with Fe-S clusters, and cell envelope biosynthetic enzymes were highlighted. These data suggest that 8HQs do not have a specific intracellular target, but act as copper ionophores, and that the mode of action is via copper-dependent toxicity.

Drug-resistant Mycobacterium tuberculosis is a significant cause of infectious disease morbidity and mortality for which new antimicrobials are urgently needed. Inhibitors of mycobacterial respiratory energy metabolism have emerged as promising next-generation antimicrobials, but a number of targets remain unexplored. Succinate dehydrogenase (SDH), a focal point in mycobacterial central carbon metabolism and respiratory energy production, is required for growth and survival in M. tuberculosis under a number of conditions, highlighting the potential of inhibitors targeting mycobacterial SDH enzymes. To advance SDH as a novel drug target in M. tuberculosis , we utilized a combination of biochemical screening and in-silico deep learning technologies to identify multiple chemical scaffolds capable of inhibiting mycobacterial SDH activity. Antimicrobial susceptibility assays show that lead inhibitors are bacteriostatic agents with activity against wild-type and drug-resistant strains of M. tuberculosis . Mode of action studies on lead compounds demonstrate that the specific inhibition of SDH activity dysregulates mycobacterial metabolism and respiration and results in the secretion of intracellular succinate. Interaction assays demonstrate that the chemical inhibition of SDH activity potentiates the activity of other bioenergetic inhibitors and prevents the emergence of resistance to a variety of drugs. Overall, this study shows that SDH inhibitors are promising next-generation antimicrobials against M. tuberculosis .

Tuberculosis (TB), an airborne infectious disease caused by Mycobacterium tuberculosis, has become the leading cause of death. The subsequent emergence of multidrug-resistant, extensively drug-resistant and totally drug-resistant strains, brings an urgent need to discover novel anti-TB drugs. Among them, microbial-derived anti-mycobacterial peptides, including ribosomally synthesized and post-translationally modified peptides (RiPPs) and multimodular nonribosomal peptides (NRPs), now arise as promising candidates for TB treatment. This review presents 96 natural RiPP and NRP families from bacteria and fungi that have broad spectrum in vitro activities against non-resistant and drug-resistant mycobacteria. In addition, intracellular targets of 22 molecules are the subject of much attention. Meanwhile, chemical features of 38 families could be modified in order to improve properties. In final, structure-activity relationships suggest that the modifications of various groups, especially the peptide side chains, the amino acid moieties, the cyclic peptide skeletons, various special groups, stereochemistry and entire peptide chain length are important for increasing the potency., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests. Yun Xue reports financial support was provided by National Natural Science Foundation of China. Pengchao Zhao reports financial support was provided by Open Fund of Key Laboratory of Biotechnology and Bioresources Utilization (Dalian Minzu University), Ministry of Education. Yun Xue reports a relationship with No that includes: non-financial support. Yun Xue has patent No pending to No. No If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

New 2-pyrrolamidobenzothiazole-based inhibitors of mycobacterial DNA gyrase were discovered. Among these, compounds 49 and 51, show excellent antibacterial activity against Mycobacterium tuberculosis and Mycobacterium abscessus with a notable preference for mycobacteria. Both compounds can penetrate infected macrophages and reduce intracellular M. tuberculosis load. Compound 51 is a potent inhibitor of DNA gyrase (M. tuberculosis DNA gyrase IC 50  = 4.1 nM, Escherichia coli DNA gyrase IC 50 of <10 nM), selective for bacterial topoisomerases. It displays low MIC 90 values (M. tuberculosis: 0.63 μM; M. abscessus: 2.5 μM), showing specificity for mycobacteria, and no apparent toxicity. Compound 49 not only displays potent antimycobacterial activity (MIC 90 values of 2.5 μM for M. tuberculosis and 0.63 μM for M. abscessus) and selectivity for mycobacteria but also exhibits favorable solubility (kinetic solubility = 55 μM) and plasma protein binding (with a fraction unbound of 2.9 % for human and 4.7 % for mouse). These findings underscore the potential of fine-tuning molecular properties to develop DNA gyrase B inhibitors that specifically target the mycobacterial chemical space, mitigating the risk of resistance development in non-target pathogens and minimizing harm to the microbiome., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Masson SAS.)

Background: Galatella is a genus in the family Asteraceae, represented by 35-45 species. Considering the high effectiveness of the ethyl acetate (EtOAc) fraction of G. grimmii against Mycobacterium tuberculosis (MIC = 0.5 µg/mL), a bioassay-directed fractionation of this extract was carried out., Methods: The methanolic extract of the aerial parts of G. grimmii was obtained using maceration, then it was suspended in water and partitioned with petroleum ether, dichloromethane (CH 2 Cl 2 ), EtOAc, and n-butanol (n-BuOH), successively. The most potent fraction (EtOAc), was selected for further isolation by Sephadex LH-20 and semi-preparative HPLC to obtain active compounds., Results: Fractionation of the EtOAc solvent fraction resulted in the characterization of five compounds, among them, compounds 1 and 2 showed the highest anti-mycobacterial effects with MICs of 0.062 and 1.00 µg/mL against H37Rv M. tuberculosis, respectively, which were higher than those of rifampin (MIC of 1.25 µg/mL) and isoniazid (MIC of 0.31 µg/mL), as positive controls. Also, compound 1 ​​inhibited all tested strains of drug-resistant Mycobacterium (MDR and XDR). Notably, the isolated compounds have been reported for the first time from G. grimmii., Conclusion: Due to the potent anti-mycobacterial effect of isolated compounds from G. grimmii, this study could pave the way for developing a novel class of natural anti-tuberculosis compounds., (© 2024. The Author(s).)

The mycobacterial F-ATP synthase is responsible for the optimal growth, metabolism and viability of Mycobacteria, establishing it as a validated target for the development of anti-TB therapeutics. Herein, we report the discovery of an N-acyl phenothiazine derivative, termed PT6, targeting the mycobacterial F-ATP synthase. PT6 is bactericidal and active against the drug sensitive, Rifampicin-resistant as well as Multidrug-resistant tuberculosis strains. Compound PT6 showed noteworthy inhibition of F-ATP synthesis, exhibiting an IC 50 of 0.788 µM in M. smegmatis IMVs and was observed that it could deplete intracellular ATP levels, exhibiting an IC 50 of 30 µM. PT6 displayed a high selectivity towards mycobacterial ATP synthase compared to mitochondrial ATP synthase. Compound PT6 showed a minor synergistic effect in combination with Rifampicin and Isoniazid. PT6 demonstrated null cytotoxicity as confirmed by assessing its toxicity against VERO cell lines. Further, the binding mechanism and the activity profile of PT6 were validated by employing in silico techniques such as molecular docking, Prime MM/GBSA, DFT and ADMET analysis. These results suggest that PT6 presents an attractive lead for the discovery of a novel class of mycobacterial F-ATP synthase inhibitors., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

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.

Tuberculosis (TB) is an infectious airborne disease caused by Mycobacterium tuberculosis. Since the 1990 s, many countries have made significant progress in reducing the incidence of TB and associated mortality by improving health services and strengthening surveillance systems. Nevertheless, due to the emergence of multidrug-resistant TB (MDR-TB), alongside extensively drug-resistant TB (XDR-TB) and TB-HIV co-infection, TB remains one of the lead causes of death arising from infectious disease worldwide, especially in developing countries and disadvantaged populations. Marine natural products (MNPs) have received a large amount of attention in recent years as a source of pharmaceutical constituents and lead compounds, and are expected to offer significant resources and potential in the fields of drug development and biotechnology in the years to come. This review summarizes 169 marine natural products and their synthetic derivatives displaying anti-TB activity from 2013 to the present, including their structures, sources and functions. Partial synthetic information and structure-activity relationships (SARs) are also included., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Despite the WHO's recommended treatment regimen, challenges such as patient non-adherence and the emergence of drug-resistant strains persist with TB claiming 1.5 million lives annually. In this study, we propose a novel approach by targeting the DNA replication-machinery of M.tb through drug-repurposing. The β2-Sliding clamp (DnaN), a key component of this complex, emerges as a potentially vulnerable target due to its distinct structure and lack of human homology. Leveraging TBVS, we screened ∼2600 FDA-approved drugs, identifying five potential DnaN inhibitors, by employing computational studies, including molecular-docking and molecular-dynamics simulations. The shortlisted compounds were subjected to in-vitro and ex-vivo studies, evaluating their anti-mycobacterial potential. Notably, Dicoumarol, Paromomycin, and Posaconazole exhibited anti-TB properties with a MIC value of 6.25, 3.12 and 50 μg/ml respectively, with Dicoumarol and Paromomycin, demonstrating efficacy in reducing live M.tb within macrophages. Biophysical analyses confirmed the strong binding-affinity of DnaN drug complexes, validating our in-silico predictions. Moreover, RNA-Seq data revealed the upregulation of proteins associated with DNA repair and replication mechanisms upon Paromomycin treatment. This study explores repurposing FDA-approved drugs to target TB via the mycobacterial DNA replication-machinery, showing promising inhibitory effects. It sets the stage for further clinical research, demonstrating the potential of drug repurposing in TB treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Tuberculosis (TB) is an infectious disease that primarily affects the lungs of humans and accounts for Mycobacterium tuberculosis (Mtb) bacteria as the etiologic agent. In this study, we introduce a computational framework designed to identify the important chemical features crucial for the effective inhibition of Mtb β-CAs. Through applying a mechanistic model, we elucidated the essential features pivotal for robust inhibition. Using this model, we engineered molecules that exhibit potent inhibitory activity and introduce relevant novel chemistry. The designed molecules were prioritized for synthesis based on their predicted pKi values via the QSAR (Quantitative Structure-Activity Relationship) model. All the rationally designed and synthesized compounds were evaluated in vitro against different carbonic anhydrase isoforms expressed from the pathogen Mtb; moreover, the off-target and widely human-expressed CA I and II were also evaluated. Among the reported derivatives, 2, 4, and 5 demonstrated the most valuable in vitro activity, resulting in promising candidates for the treatment of TB infection. All the synthesized molecules exhibited favorable pharmacokinetic and toxicological profiles based on in silico predictions. Docking analysis confirmed that the zinc-binding groups bind effectively into the catalytic triad of the Mtb β-Cas, supporting the in vitro outcomes with these binding interactions. Furthermore, molecules with good prediction accuracies according to previously established mechanistic and QSAR models were utilized to delve deeper into the realm of systems biology to understand their mechanism in combating tuberculotic pathogenesis. The results pointed to the key involvement of the compounds in modulating immune responses via NF-κβ1, SRC kinase, and TNF-α to modulate granuloma formation and clearance via T cells. This dual action, in which the pathogen's enzyme is inhibited while modulating the human immune machinery, represents a paradigm shift toward more effective and comprehensive treatment approaches for combating tuberculosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The increasing prevalence of drug-resistant Mycobacterium tuberculosis strains stimulates the discovery of new drug candidates. Among them are 8-hydroxyquinoline (8HQ) derivatives that exhibited antimicrobial properties. Unfortunately, there is a lack of data assessing possible targets for this class mainly against Mycobacterium tuberculosis enoyl-acyl carrier protein reductase (MtInhA), a validated target in this field. Thus, the main purpose of this study was to identify 8HQ derivatives that are active against M. tuberculosis and MtInhA. Initially, the screening against the microorganism of a small antimicrobial library and its new derivatives that possess some structural similarity with MtInhA inhibitors identified four 7-substituted-8HQ (series 5 - 5a, 5c, 5d and 5i) and four 5-substituted-8HQ active derivatives (series 7 - 7a, 7c, 7d and 7j). In general, the 7-substituted 8-HQs were more potent and, in the enzymatic assay, were able to inhibit MtInhA at low micromolar range. However, the 5-substituted-8-HQs that presented antimycobacterial activity were not able to inhibit MtInhA. These findings indicate the non-promiscuous nature of 8-HQ derivatives and emphasize the significance of selecting appropriate substituents to achieve in vitro enzyme inhibition. Finally, 7-substituted-8HQ series are promising new derivatives for structure-based drug design and further development., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

In pursuit of potential chemotherapeutic alternates to combat severe tuberculosis infections, novel heterocyclic templates derived from clinically approved anti-TB drug isoniazid and isatin have been synthesized that demonstrate potent inhibitory action against Mycobacterium tuberculosis, and compound 4i with nitrophenyl motif exhibited the highest anti-TB efficacy with a MIC value of 2.54 μM/ml. Notably, the same nitro analog 4i shows the best antioxidant efficacy among all the synthesized compounds with an IC 50 value of 37.37 μg/ml, suggesting a synergistic influence of antioxidant proficiency on the anti-TB action. The titled compounds exhibit explicit binding affinity with the InhA receptor. The befitting biochemical reactivity and near-appropriate pharmacokinetic proficiency of the isoniazid conjugates is reflected in the density functional theory (DFT) studies and ADMET screening. The remarkable anti-TB action of the isoniazid cognates with marked radical quenching ability may serve as a base for developing multi-target medications to confront drug-resistant TB pathogens., (© 2024 Wiley-VHCA AG, Zurich, Switzerland.)

The treatment of Mycobacterium avium infections is still long, complex, and often poorly tolerated, besides emergence of resistances. New active molecules that are more effective and better tolerated are deeply needed. Mefloquine and its enantiomers ((+) Erythro-mefloquine ((+)-EMQ) and (-)-Erythro-mefloquine ((-)-EMQ)) have shown efficacy in both in vitro and in vivo, in a mouse model of M. avium intraveinous infection. However, no study reports aerosol model of infection or combination with gold standard treatment. That was the aim of our study. In an aerosol model of M. avium infection in BALB/c mice, we used five treatment groups as followed: Clarithromycin-Ethambutol-Rifampicin (CLR-EMB-RIF, standard of care, n = 15), CLR-EMB-MFQ (n = 15), CLR-EMB-(+)-EMQ (n = 15), CLR-EMB-(-)-EMQ (n = 15) and an untreated group (n = 25). To evaluate drug efficacy, we sacrificed each month over 3 months, 5 mice from each group. Lung homogenates were diluted and plated for colony forming unit count (CFU) expressed in Log10. At each time point, we found a significant difference between the untreated group and each of the treatment groups (p<0.005). The (+)-EMQ-CLR-EMB group was the group with the lowest CFU count at each time point but never reached statistical significance. The results of each group 3 months after treatment are: (+)-EMQ-CLR-EMB (4.43 ± 0.26), RIF-CLR-EMB (4.83 ± 0.37), (-)-EMQ-CLR-EMB (4.82 ± 0.18), MFQ-CLR-EMB (4.70 ± 0.21). In conclusion, MFQ and its enantiomers appear to be as effective as rifampicin in combination therapy. Further studies are needed to evaluate the ability of these drugs to prevent selection of clarithromycin resistant strains and potential for lung sterilization., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Froment et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

A focussed library of pyridyl and 2-hydroxyphenyl chalcones were synthesized and tested for growth inhibitory activity against Mycobacterium tuberculosis H37Rv, and normal and cancer breast cell lines. Pyridyl chalcones bearing lipophilic A-ring, e.g., dichloro-phenyl-( 14 ), pyrene-1-yl ( 20 )- and biphenyl-4-yl ( 21 ) moieties were found to be the most potent of the series inhibiting the growth of M. tuberculosis H37Rv with IC 90 values ranging from 8.9-28 µM. Aryl chalcones containing a 3-methoxyphenyl A-ring and either p -Br-phenyl ( 25 ) or p -Cl-phenyl ( 26 ) B-rings showed an IC 90 value of 28 µM. Aryl-chalcones were generally less toxic to HepG2 cells compared to pyridyl-chalcones. Dose-dependent antiproliferative activity against MDA468 cells was observed for trimethoxy-phenyl ( 16 ) and anthracene-9-yl ( 19 ) pyridyl-chalcones with IC 50 values of 0.7 and 0.3 µM, respectively. Docking studies revealed that chalone 20 was predicted to bind to the M. tuberculosis protein tyrosine phosphatases B (PtpB) with higher affinity compared to a previously reported PtpB inhibitor.

Toward repositioning the antitubercular clinical candidate SQ109 as an antimalarial, analogs were investigated for structure-activity relationships for activity against asexual blood stages of the human malaria parasite Plasmodium falciparum pathogenic forms, as well as transmissible, sexual stage gametocytes. We show that equipotent activity (IC 50 ) in the 100-300 nM range could be attained for both asexual and sexual stages, with the activity of most compounds retained against a multidrug-resistant strain. The multistage activity profile relies on high lipophilicity ascribed to the adamantane headgroup, and antiplasmodial activity is critically dependent on the diamine linker. Frontrunner compounds showed conserved activity against genetically diverse southern African clinical isolates. We additionally validated that this series could block transmission to mosquitoes, marking these compounds as novel chemotypes with multistage antiplasmodial activity.

Thiopeptides are ribosomally biosynthesized and post-translationally modified peptides (RiPPs) that potently inhibit the growth of Gram-positive bacteria by targeting multiple steps in protein biosynthesis. The poor pharmacological properties of thiopeptides, particularly their low aqueous solubility, has hindered their development into clinically useful antibiotics. Antimicrobial activity screens of a library of Actinomycetota extracts led to discovery of the novel polyglycosylated thiopeptides persiathiacins A and B from Actinokineospora sp. UTMC 2448. Persiathiacin A is active against methicillin-resistant Staphylococcus aureus and several Mycobacterium tuberculosis strains, including drug-resistant and multidrug-resistant clinical isolates, and does not significantly affect the growth of ovarian cancer cells at concentrations up to 400 μM. Polyglycosylated thiopeptides are extremely rare and nothing is known about their biosynthesis. Sequencing and analysis of the Actinokineospora sp. UTMC 2448 genome enabled identification of the putative persiathiacin biosynthetic gene cluster (BGC). A cytochrome P450 encoded by this gene cluster catalyzes the hydroxylation of nosiheptide in vitro and in vivo, consistent with the proposal that the cluster directs persiathiacin biosynthesis. Several genes in the cluster encode homologues of enzymes known to catalyze the assembly and attachment of deoxysugars during the biosynthesis of other classes of glycosylated natural products. One of these encodes a glycosyl transferase that was shown to catalyze attachment of a D-glucose residue to nosiheptide in vitro. The discovery of the persiathiacins and their BGC thus provides the basis for the development of biosynthetic engineering approaches to the creation of novel (poly)glycosylated thiopeptide derivatives with enhanced pharmacological properties.

Liposomal formulations of antibiotics for inhalation offer the potential for the delivery of high drug doses, controlled drug release kinetics in the lung, and an excellent safety profile. In this study, we evaluated the in vivo performance of a liposomal formulation for the poorly soluble, antituberculosis agent, bedaquiline. Bedaquiline was encapsulated within monodisperse liposomes of ∼70 nm at a relatively high drug concentration (∼3.6 mg/mL). Formulations with or without fucose residues, which bind to C-type lectin receptors and mediate a preferential binding to macrophage mannose receptor, were prepared, and efficacy was assessed in an in vivo C3HeB/FeJ mouse model of tuberculosis infection (H37Rv strain). Seven intranasal instillations of 5 mg/kg bedaquiline formulations administered every second day resulted in a significant reduction in lung burden (∼0.4-0.6 Δlog 10 CFU), although no differences between fucosylated and nonfucosylated formulations were observed. A pharmacokinetic study in healthy, noninfected Balb/c mice demonstrated that intranasal administration of a single dose of 2.5 mg/kg bedaquiline liposomal formulation (fucosylated) improved the lung bioavailability 6-fold compared to intravenous administration of the same formulation at the same dose. Importantly, intranasal administration reduced systemic concentrations of the primary metabolite, N -desmethyl-bedaquiline (M2), compared with both intravenous and oral administration. This is a clinically relevant finding as the M2 metabolite is associated with a higher risk of QT-prolongation in predisposed patients. The results clearly demonstrate that a bedaquiline liposomal inhalation suspension may show enhanced antitubercular activity in the lung while reducing systemic side effects, thus meriting further nonclinical investigation.

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.

Central nervous system tuberculosis (CNS-TB) is a severe form of extra-pulmonary tuberculosis with high mortality and morbidity rates. The standard treatment regimen for CNS-TB parallels that of pulmonary TB, despite the challenge posed by the blood-brain barrier (BBB), which limits the efficacy of first-line anti-TB drugs (ATDs). Nose-to-brain (N2B) drug delivery offers a promising solution for achieving high ATD concentrations directly at infection sites in the brain while bypassing the BBB. This study aimed to develop chitosan nanoparticles encapsulating ATDs, specifically isoniazid (INH) and rifampicin (RIF). These nanoparticles were further processed into micro-sized chitosan nano-aggregates (NA) via spray drying. Both INH-NA and RIF-NA showed strong mucoadhesion and significantly higher permeation rates across RPMI 2650 cells compared to free ATDs. Intranasal administration of these NAs to TB-infected mice for four weeks resulted in a significant reduction of mycobacterial load by approximately ∼2.86 Log 10 CFU compared to the untreated group. This preclinical data highlights the efficacy of intranasal chitosan nano-aggregates in treating CNS-TB, demonstrating high therapeutic potential, and addressing brain inflammation challenges. To our knowledge, this study is the first to show nasal delivery of ATD nano-formulations for CNS-TB management.

Tuberculosis (TB) remains a major public health challenge, with research on new anti-TB drugs crucial for global TB elimination efforts. Here, we report a novel class of anti-TB agents. Especially, compounds 5b and 5j exhibited the highest activity [minimum inhibitory concentration (MIC) H37Rv: 0.16 and 0.12 μg/mL]. Chiral resolution was performed on compounds 5b and 5j ; the isomers were evaluated for their activity and safety, confirming that the R -isomer 5bb and 5jb displayed significant anti-TB activity (MIC H37Rv: 0.03-0.06 μg/mL; MDR- Mtb : 0.125-0.06 μg/mL) and low hERG toxicity. Further evaluations on 5bb and 5jb demonstrated good metabolic stability, favorable kinetic parameters and oral bioavailability (F: 56.7 and 63.8%, respectively). The results of in vivo activity assessment indicate that 5bb and 5jb exhibit protective and therapeutic effects on zebrafish larvae and adult zebrafish infected with Mycobacterium marinum . Based on these results, compounds 5bb and 5jb are considered promising candidates for further in-depth studies.

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., (© 2024 John Wiley & Sons Ltd.)

Two libraries of quinoline-based hybrids 1-(7-chloroquinolin-4-yl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine and 7-chloro-N-phenylquinolin-4-amine were synthesized and evaluated for their α-glucosidase inhibitory and antioxidant properties. Compounds with 4-methylpiperidine and para-trifluoromethoxy groups, respectively, showed the most promising α-glucosidase inhibition activity with IC 50 =46.70 and 40.84 μM, compared to the reference inhibitor, acarbose (IC 50 =51.73 μM). Structure-activity relationship analysis suggested that the cyclic secondary amine pendants and para-phenyl substituents account for the variable enzyme inhibition. Antioxidant profiling further revealed that compounds with an N-methylpiperazine and N-ethylpiperazine ring, respectively, have good DPPH scavenging abilities with IC 50 =0.18, 0.58 and 0.93 mM, as compared to ascorbic acid (IC 50 =0.05 mM), while the best DPPH scavenger is NO 2 -substituted compound (IC 50 =0.08 mM). Also, compound with N-(2-hydroxyethyl)piperazine moiety emerged as the best NO radical scavenger with IC 50 =0.28 mM. Molecular docking studies showed that the present compounds are orthosteric inhibitors with their quinoline, pyrimidine, and 4-amino units as crucial pharmacophores furnishing α-glucosidase binding at the catalytic site. Taken together, these compounds exhibit dual potentials; i. e., potent α-glucosidase inhibitors and excellent free radical scavengers. Hence, they may serve as structural templates in the search for agents to manage Type 2 diabetes mellitus. Finally, in preliminary assays investigating the anti-tubercular potential of these compounds, two pyrazolopyrimidine series compounds and a 7-chloro-N-phenylquinolin-4-amine hybrid showed sub-10 μM whole-cell activities against Mycobacterium tuberculosis., (© 2024 The Authors. ChemistryOpen published by Wiley-VCH GmbH.)

Over the past 2000 years, tuberculosis (TB) has been responsible for more deaths than any other infectious disease. In recent years, there has been a recovery of research and development (R&D) efforts focused on TB drugs. This is driven by the pressing need to combat the global spread of the disease and develop improved therapies for both drug-sensitive and drug-resistant strains. Many new TB drug candidates have recently entered clinical trials, marking the beginning of a rebirth in this area after decades of neglect. The problem is that very few of the hundreds of compounds identified each year as potential anti-TB drugs really make it to the clinical development stage. This perspective focuses on the primary obstacles and approaches involved in the development of new medications for TB. This will help medicinal chemists better understand TB drug challenges and develop novel drug candidates., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This study aims to investigate the therapeutic potential of herbal remedies, specifically resveratrol and lignans, as alternative treatments for tuberculosis (TB), given the challenges posed by drug-resistant strains and adverse effects of conventional therapies. A comprehensive review of the literature was conducted to analyze the mechanisms of action, safety profiles, and efficacy of resveratrol and lignans in the context of TB management. This review focused on the bactericidal and bacteriostatic effects of these compounds, examining their interaction with Mycobacterium tuberculosis within macrophages. Resveratrol and lignans were found to exhibit significant antibacterial properties through mechanisms such as SIRT1 modulation, coenzyme A transferase inhibition, suppression of intracellular bacterial proliferation in macrophages, and induction of autophagy. These mechanisms contribute to their effectiveness in combating TB and highlight their potential as alternative therapeutic agents., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The emergence of superbugs of multi-drug resistant (MDR/RR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis ( Mtb ) strains at a faster rate is posing a serious threat to Tuberculosis (TB) control worldwide. Mtb enoyl-acyl carrier protein reductase (InhA) is a well-established target of the front-line anti-TB prodrug Isoniazid (INH), which requires activation by Catalase-peroxidase enzyme (KatG) in order to inhibit InhA enzyme, that is crucial for the biosynthesis of the mycobacterial cell wall. Currently, due to widespread resistance to this drug, it is necessary to identify new clinical candidates that directly inhibit InhA enzyme and do not require activation by KatG, thereby circumventing most of the resistance mechanisms. In the present study, high-throughput virtual screening of ASINEX database was carried out to identify potential direct inhibitors of Mtb InhA. Best twenty compounds with good binding energies ranging between -12.36 and -9.27 kcal/mol were selected as promising virtual screening hits. These molecules were subjected to ADME study followed by toxicity prediction. Finally, four top-ranked molecules which are structurally diverse and possess best binding affinity than the co-crystalized ligand have been chosen for MD simulation studies followed by MM-GBSA analysis to validate and ensure the stability of hits in the active site of the enzyme. Based on the 100 ns MD simulation studies and binding free energy estimates, three hit molecules B244, B369, and B310 could be considered as potential inhibitors for Mtb InhA, which are likely to be potent against INH-resistant Mtb strains after successful experimental validation.Communicated by Ramaswamy H. Sarma.

Rifampicin is a frontline antibiotic in the management of tuberculosis. Since no spectrofluorimetric methods are reported for this drug, this approach was challenged to craft a sensitive, reliable, valid, fast, and green methodology. In recent years, fluorescence spectroscopy has received a lot of interest. Its benefits include ecological greenness and analytical performance. The pharmaceutical industries greatly like this approach because of its low energy and decreased solvent usage, which make it both economical and environmentally friendly. This methodology was based on utilizing the enhanced native fluorescence of the rifampicin at 341 nm after excitation at 241 nm in a beta-cyclodextrin micellar system. Modern developments in analytical chemistry have been applied to reduce risks to the workplace and environment by using distilled water as a dilution solvent for method application and optimization. The method was found excellent green with 97 eco-scale and 0.86 AGREE scores besides an 89.6 overall whiteness score. The range of linearity for rifampicin raw material was 0.2-1.5 μg·mL -1 , and the average recoveries for raw material and spiked plasma were 100.15% and 99.64%, respectively. The suggested technique worked well for the commercial oral syrup of Rimactane® and did not conflict with any common additives., (© 2024 John Wiley & Sons Ltd.)

Tuberculosis is a global serious problem that imposes major health, economic and social challenges worldwide. The search for new antitubercular drugs is extremely important which could be achieved via inhibition of different druggable targets. Mycobacterium tuberculosis enoyl acyl carrier protein reductase (InhA) enzyme is essential for the survival of M. tuberculosis. In this investigation, a series of coumarin based thiazole derivatives was synthesized relying on a molecular hybridization approach and was assessed against thewild typeMtb H37Rv and its mutant strain (ΔkatG) via inhibiting InhA enzyme. Among the synthesized derivatives, compounds 2b, 3i and 3j were the most potent against wild type M. tuberculosis with MIC values ranging from 6 to 8 μg/ mL and displayed low cytotoxicity towards mouse fibroblasts at concentrations 8-13 times higher than the MIC values. The three hybrids could also inhibit the growth of ΔkatGmutant strain which is resistant to isoniazid (INH). Compounds 2b and 3j were able to inhibit the growth of mycobacteria inside human macrophages, indicating their ability to penetrate human professional phagocytes. The two derivatives significantly suppress mycobacterial biofilm formation by 10-15 %. The promising target compounds were also assessed for their inhibitory effect against InhA and showed potent effectiveness with IC 50 values of 0.737 and 1.494 µM, respectively. Molecular docking studies revealed that the tested compounds occupied the active site of InhA in contact with the NAD + molecule. The 4-phenylcoumarin aromatic system showed binding interactions within the hydrophobic pocket of the active site. Furthermore, H-bond formation and π -π stacking interactions were also recorded for the promising derivatives., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Mycobacterium tuberculosis ( Mtb ) is one of the major causes of death worldwide and there is a pressing need for the development of novel drug leads. The Imidazole Glycerol Phosphate Dehydratase (IGPD) of Mtb is one of the key enzymes in the histidine biosynthesis pathway and has been recognized as the potentially underexploited drug target for anti-tuberculosis treatment. In the present study, 6063 structurally diverse plant secondary metabolites (PSM) were screened for their efficiency in inhibiting the catalytic activity of IGPD through molecular docking. The top 150 PSMs with the lowest binding energy represent the chemical classes, including Tannins (34%), Flavonoid Glycosides (14%), Terpene Glycosides (10%), Steroid Lactones (9.3%), Flavonoids (6.6%), Steroidal Glycosides (4.6%), etc. Bismahanine, Ashwagandhanolide, and Daurisoline form stable IGPD-inhibitor complexes with binding free energies of -291.3 ± 16.5, -279.0 ± 25.0, and -279.8 ± 17.6 KJ/mol, respectively, as determined by molecular dynamics simulations. These PSM demonstrated strong H-bond interactions with the amino acid residues Ile279, Arg281, and Lys276 in the catalytic region of IGPD, as revealed by structural snapshots. On the basis of our findings, these three PSM could be considered as possible leads against IGPD and should be explored in vitro and in vivo .Communicated by Ramaswamy H. Sarma.

Tuberculosis (TB) continues to pose a grave threat to global health, despite relentless eradication efforts. In 1882, Robert Koch discovered that Mycobacterium tuberculosis (Mtb) is the bacterium responsible for causing tuberculosis. It is a fact that tuberculosis has claimed the lives of more than one billion people in the last few decades. It is imperative that we must take immediate and effective action to increase resources for TB research and treatment. Effective TB treatments demand an extensive investment of both time and finances, often requiring 6-9 months of rigorous antibiotic therapy. The most efficient way to control tuberculosis is by receiving a childhood Bacillus Calmette-Guérin (BCG) vaccination. Despite years of research on vaccine development, we still do not have any new approved vaccine for tuberculosis, except BCG, which is partially effective in young children. This review discusses briefly the available treatment for tuberculosis and remarkable advancements in glycoconjugate-based TB vaccine developments in recent years (2013-2024) and offers valuable direction for future research priorities., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Personalized medicine is a rapidly revolving field that offers new opportunities for tailoring disease treatment to individual patients. The main idea behind this approach is to carefully select safe and effective medications and treatment plant based on each patient's unique pharmacokinetic profile. Isoniazid is a first-line anti-tuberculosis drug that has interindividual variability in its metabolic processing, leading to significant differences in plasma concentrations among patients receiving equivalent doses. This variability necessitates the creation of individualized treatment regimens as part of personalized medicine to achieve more effective therapy., Results: In this work, a deep eutectic solvent-based liquid-liquid microextraction approach for the separation and determination of isoniazid in human plasma by high-performance liquid chromatography with UV-Vis detection was developed for the first time. A new natural deep eutectic solvent based on thymol as a hydrogen bond donor and 4-methoxybenzaldehyde as a hydrogen bond acceptor was proposed as the extraction solvent. The developed microextraction procedure assumed two simultaneous processes during the mixing of the sample and extraction solvent: the derivatization of the polar analyte in the presence of 4-methoxybenzaldehyde (component of the natural deep eutectic solvent) with the formation of a hydrophobic Schiff base (1); mass transfer of the Schiff base from the sample phase to the extraction solvent phase (2). Under optimal conditions, the limits of detection and quantification were 20 and 60 μg L -1 , respectively. The RSD value was <10 %, the extraction recovery was 95 %., Significance: In this work, the possibility of isoniazid derivatization in the natural deep eutectic solvent phase with the formation of the Schiff base was presented for the first time. The approach provided the separation and preconcentration of polar isoniazid without the use of expensive derivatization agents and solid-phase extraction cartridges. The formation of the Schiff base was confirmed by mass spectrometry., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Resistant M. tuberculosis strains threaten pulmonary tuberculosis (P-TB) control since they limit drug options. Drug repositioning and new development strategies are urgently required to overcome resistance. Studies have already shown the beneficial role of the oral antidiabetic metformin as an anti-tuberculosis adjuvant drug. This work aimed to develop an inhalatory dry powder co-formulation of metformin and moxifloxacin to figure out a future option for P-TB treatment. Pre-formulation evaluations indicated the physicochemical compatibility of constituents, demonstrating powder crystallinity and acceptable drug content. Eight moxifloxacin-metformin dry powder formulations were produced by spray drying, and solid-state characterizations showed partial amorphization, ascribed to moxifloxacin. Four formulations containing L-leucine exhibited micromeritic and in vitro deposition profiles indicating pulmonary delivery suitability, like spherical and corrugated particle surface, geometric diameters < 5 μm, high emitted doses (>85 %), and mass median aerodynamic diameters between 1-5 μm. The use of a second spray dryer model further optimized the aerodynamic properties and yield of the best formulation, demonstrating the influence of the equipment used on the product obtained. Moreover, the final formulation showed high in vitro cell tolerability and characteristics in permeability studies indicative of good drug retention in the lungs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this study, a series of novel thieno [3, 2-b]pyridinone derivatives were designed and synthesized using a scaffold hopping strategy. Six compounds showed potent anti-mycobacterial activity (minimum inhibitory concentration (MIC) ≤ 1 μg/mL) against Mycobacterium tuberculosis (Mtb) UAlRa. Compound 6c displayed good activity against Mtb UAlRv (MIC = 0.5-1 μg/mL). Compounds 6c and 6i also showed activity against Mtb UAlRa in macrophages and exhibited low cytotoxicity against LO-2 cells. The selected compounds displayed a narrow antibacterial spectrum, with no activity against representative Gram-positive, Gram-negative bacteria, as well as fungi. Furthermore, compound 6c demonstrated favorable oral pharmacokinetic properties with a T 1/2 value of 47.99 h and exhibited good in vivo activity in an acute mouse model of tuberculosis (TB). The target of compound 6c was identified as a NADH-dependent enoyl-acyl carrier protein reductase (InhA) by genome sequencing of spontaneously compound 6c-resistant Mtb mutants, indicating that compound 6c may not require activation and can directly target InhA. In vitro antimicrobial assays against a recombinant M. smegmatis overexpressing the Mtb-InhA, along with InhA inhibition assays, confirmed that InhA is the target of thieno [3, 2-b]pyridinone derivatives. Overall, this study identified thieno [3, 2-b]pyridinone scaffold as a novel chemotype that is promising for the development of anti-TB agents., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Masson SAS.)

Nitrobenzothiazinones (BTZs) represent a novel type of antitubercular agents targeting DprE1. Two clinical candidates BTZ043 and PBTZ169, as well as many other BTZs showed potent anti-TB activity, but they are all highly lipophilic and their poor aqueous solubility is still a serious issue need to be addressed. Here, we designed and synthesized a series of new BTZ derivatives, wherein a hydrophilic COOH or NH 2 group is directly attached to the oxime moiety of TZY-5-84 discovered in our lab, through various linkers. Two compounds 1a and 3 were first reported to possess excellent activity against MTB H 37 Rv and MDR-MTB strains (MIC: <0.029-0.095 μM), low toxicity and acceptable oral PK profiles, as well as significantly improved water solubility (1200 and > 2000 μg/mL, respectively), suggesting they may serve as promising hydrophilic BTZs for further antitubercular drug discovery., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Bedaquiline (BDQ) is a drug used to treat multidrug-resistant tuberculosis (MDR-TB). It exhibits exposure-dependent efficacy in eliminating Mycobacterium tuberculosis (Mtb). An easy, efficient and precise reverse-phase ultrafast liquid chromatography (RP-UFLC) method was developed to validate the free base of the antitubercular medication BDQ. BDQ was separated using a 10:90 v/v mobile phase of ammonium acetate buffer solution (pH = 5.4) and high-performance liquid chromatography-grade methanol, with a flow rate of 1.5 mL/min and a UV detection wavelength of 226 nm. By using the Box-Behnken design (BBD) and response surface methodology (RSM), the method was optimised by varying critical analytical attributes (CAA) and critical performance attributes (CPAs) namely ammonium acetate fraction (%), flow rate (ml/min), buffer system molarity (M) and pH. BDQ was eluted at 7.5 min utilising isocratic elution. The method was linear in the concentration range of 0.5-300 μg/mL with limit of detection values of 0.039 μg/mL and limit of quantification of 0.12 μg/mL. The results indicate that this validated method can be used as an alternative method for assay of BDQ., (© 2024 The Author(s). Biomedical Chromatography published by John Wiley & Sons Ltd.)