Development Of Anti-tuberculosis Drugs Research Articles

3D-QSAR study of adenosine 5’-phosphosulfate (APS) analouges as ligands for APS reductase

Metabolism of sulfur (sulfur assimilation pathway, SAP) is one of the key pathways for the pathogenesis and survival of persistant bacteria, such as Mycobacterium tuberculosis (Mtb), in the latent period. Adenosine 5'-phosphosulfate reductase (APSR) is an important enzyme involved in the SAP, absent from the human body, so it might represent a valid target for development of new antituberculosis drugs. This work aimed to develop 3D-QSAR model based on the crystal structure of APSR from Pseudomonas aeruginosa, which shows high degree of homology with APSR from Mtb, in complex with its substrate, adenosine 5'-phosphosulfate (APS). 3D-QSAR model was built from a set of 16 nucleotide analogues of APS using alignment-independent descriptors derived from molecular interaction fields (MIF). The model improves the understanding of the key characteristics of molecules necessary for the interaction with target, and enables the rational design of novel small molecule inhibitors of Mtb APSR.

Drug Sensitivity Testing of Mycobacterium tuberculosis Growing in a Hollow Fiber Bioreactor.

Hollow fiber systems (HFSs) have been widely applied to study pharmacokinetic-pharmacodynamic (PK-PD) relationships in antibiotic research and development. The system comprises a bundle of high-density hollow capillary fibers that conduct a flow of medium with or without drug and an extra-capillary space (ECS) inoculated with the pathogen of interest. The semipermeable membrane of the hollow fibers allows for rapid exchange of small molecule drugs and solutes, while the pathogen is restricted to the ECS. The unique properties of the HFS are (1) the ability to simulate any PK profile within the fibers and ECS, including plasma or site-of-disease PK profiles, (2) the ability to simultaneously input several drugs with different half-lives, (3) the ability to manipulate growth conditions such as medium composition, carbon source, and pH, and (4) the ability to sample in both compartments in order to monitor drug concentrations and bacterial growth kinetics over time. The system is particularly suited for Mycobacterium tuberculosis research in a biosafety level 3 (BSL3) environment since pathogenic bacteria are sequestered in an isolated compartment. The HFS was qualified by the European Medicines Agency for antituberculosis drug development in 2015. Here, we describe the standard procedures used to study the growth kinetics of M. tuberculosis in the HFS and the killing effect of first-line antituberculous drugs applied under simulated human PK conditions. This animal-sparing and economical tool can be applied to optimize dosing schedules that minimize emergence of resistance and to prioritize drug regimens that accelerate sterilization.

PP382 Research On The Second-Line Anti-Tuberculosis Drugs Supply Based On Stakeholder Theory Of China

IntroductionChina is one of the twenty-seven countries with a high burden of Multidrug-resistant tuberculosis (MDR-TB) in the world. Of the new TB patients in China in 2017, about 63,000 are MDR-TB patients, accounting for one-third of the number of new MDR-TB patients worldwide.In the latest “China's 13th Five-Year Plan” national TB prevention and control plan promulgated in 2017, it is clearly emphasized that all regions should gradually incorporate TB into the payment catalogue of special outpatient medical insurance, according to local conditions. However, for this special group of MDR-TB patients, there is no specialized prevention and control policy at the national level, and there are also blind spots in the medical security policy.Responding to the drug needs of MDR-TB patients, it is necessary to provide patients with stable and affordable second-line anti-TB drugs. It is also necessary to understand the overall drug demand for second-line drugs nationwide to guide further policy formulation and budget research.MethodsThrough semi-structured group interviews and key informant interviews, five provinces and cities were investigated. Qualitative analysis was conducted based on stakeholder theory selected doctors and staff from Centers for Disease Control.ResultsThrough investigations in this study, problems like low purchasing price, insufficient purchasing volume, low drug supply efficiency, and monopoly producers were found. Through the analysis of roles and relationships among the major stakeholders in the second-line drug supply system, together with the motivation and resistance factors, it was found that all stakeholders have the motivation to solve the problem and face their dilemmas and obstacles at the same time.ConclusionsPatients with MDR-TB still have difficulties in obtaining medicines. The interests of various stakeholders need to be balanced to improve drug accessibility and affordability. It is recommended to take advantage of the country's centralized procurement, encourage the development and listing of new anti-tuberculosis drugs and generic drugs, and improve the supervision system to ensure the supply of drugs to benefit more patients with tuberculosis.

Identification of fusarielin M as a novel inhibitor of Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB)

The secreted Mycobacterium tuberculosis (Mtb) protein tyrosine phosphatase B (MptpB) is an essential virulence factor required for the intracellular survival of Mtb within host macrophages. MptpB has become a promising target for the development of novel anti-tuberculosis (TB) drugs. In this study, two new fusarielins, fusarielins M (1) and N (2), and a biogenetically related known compound, fusarielin G (3) were isolated from the marine-derived fungus Fusarium graminearum SYSU-MS5127. Their inhibitory effects on MptpB were evaluated. Among these compounds, fusarielin M substantially inhibited MptpB with a half-maximal inhibitory concentration (IC50) of 1.05 ± 0.08 μM, and an inhibition constant (Ki) of 1.03 ± 0.39 μM. Surface plasmon resonance analysis was used to characterize the interaction between fusarielin M and MptpB in vitro. Fusarielin M also exhibited cellular activity in blocking MptpB-mediated Erk1/2 and p38 inactivation in macrophages. Importantly, fusarielin M (20 μM) substantially reduced intracellular mycobacterial growth within macrophages, causing a 62% reduction in the bacterial burden. The binding mode of fusarielin M was further explored via molecular docking which suggested that fusarielin M binds to the active site of MptpB, forming a hydrogen bond with the side chain of Asp165; this is unique in the P-loop of MptpB compared to conventional human PTPs. The contact between fusarielin M and Asp165 in the catalytic loop provides a potential basis for inhibitor selectivity. Therefore, fusarielin M shows great potential as an anti-TB drug candidate.

Handling the Hurdles on the Way to Anti-tuberculosis Drug Development.

The global epidemic of tuberculosis (TB) imposes a sustained epidemiologic vigilance and investments in research by governments. Mycobacterium tuberculosis, the main causative agent of TB in human beings, is a very successful pathogen, being the main cause of death in the population among infectious agents. In 2018, ~10 million individuals were contaminated with this bacillus and became ill with TB, and about 1.2 million succumbed to the disease. Most of the success of the M. tuberculosis to linger in the population comes from its ability to persist in an asymptomatic latent state into the host and, in fact, the majority of the individuals are unaware of being contaminated. Even though TB is a treatable disease and is curable in most cases, the treatment is lengthy and laborious. In addition, the rise of resistance to first-line anti-TB drugs elicits a response from TB research groups to discover new chemical entities, preferably with novel mechanisms of action. The pathway to find a new TB drug, however, is arduous and has many barriers that are difficult to overcome. Fortunately, several approaches are available today to be pursued by scientists interested in anti-TB drug development, which goes from massively testing chemical compounds against mycobacteria, to discovering new molecular targets by genetic manipulation. This review presents some difficulties found along the TB drug development process and illustrates different approaches that might be used to try to identify new molecules or targets that are able to impair M. tuberculosis survival.

Structure-based Discovery of Narirutin as a Shikimate kinase Inhibitor with Anti-tubercular Potency.

Shikimate pathway is essential for tubercular bacillus but it is absent in mammals. Therefore, Shikimate kinase and other enzymes in the pathway are potential targets for the development of novel anti-tuberculosis drugs. In the present study, Shikimate kinase is selected as the target for in silico screening of phytochemicals with an aim to discover a novel herbal drug against Mycobacterium tuberculosis (Mtb). A structure-based drug discovery approach is undertaken for the execution of the objective. Virtual screening of phytochemical database NPACT against the target, Shikimate kinase (PDB ID 3BAF), is carried out followed by toxicity and drug-likeness filtration. Finally, a lead, narirutin was selected for in vitro anti-tubercular study. Narirutin, present in citrus fruits, emerges as the lead. It is considered to be non-toxic with predicted high LD50 value, 12000 mg/kg body weight. The phytochemical is tested for its antitubercular activity in vitro. It has MIC99 62.5 μg/mL against the MtbH37Rv strain. This is the first-ever report to show anti-tuberculosis potency of narirutin.

Andrographolide exerts anti-inflammatory effects in Mycobacterium tuberculosis-infected macrophages by regulating the Notch1/Akt/NF-κB axis.

Tuberculosis is a serious public health problem aggravated by the slow progress in the development of newanti-tuberculosisdrugs. The hyper-reactive TB patients have suffered from chronic inflammation which could cause deleterious effects on their bodies. Therefore, it is imperative to develop an adjunctive therapy based on inflammatory modulation during Mycobacterium tuberculosis (Mtb) infection. The present study aims to investigate the immune regulatory effects of Andrographolide (Andro) on Mtb-infected macrophages and its underlying mechanisms. The results showed that Andro inhibits the production of IL-1β and other inflammatory cytokines in a dose-dependent manner. The down-regulation of IL-1β expression causes the declining expression of IL-8 and MCP-1 in lung epithelial cells which were co-cultured with Mtb-infected macrophages. The inhibition of the activation of NF-κB pathway, but not the inhibition of MAPK signaling pathway, accounts for the anti-inflammatory role of Andro. Further studies elucidated that Andro could evoke the activation of autophagy to degrade NLRP3, which ultimately inhibited inflammasome activation and subsequent IL-1β production. Finally, the relevant results demonstrated that Andro inhibited the Notch1 pathway to down-regulate the phosphorylation of Akt/mTOR and NF-κB p65 subunit. Taken together, Andro has been found to suppress the Notch1/Akt/NF-κB signaling pathway. Both Akt inhibition-induced autophagy and inhibition of the NF-κB pathway contributed to restraining the activation of NLRP3 inflammasome and subsequent IL-1β production. Then, the decreased production of IL-1β influenced chemokine expression in lung epithelial cells. Based on these results, anti-inflammatory effect of Andro in TB infection is merit further investigation.

Targeting MmpL3 for anti-tuberculosis drug development.

The unique architecture of the mycobacterial cell envelope plays an important role in Mycobacterium tuberculosis (Mtb) pathogenesis. A critical protein in cell envelope biogenesis in mycobacteria, required for transport of precursors, trehalose monomycolates (TMMs), is the Mycobacterial membrane protein large 3 (MmpL3). Due to its central role in TMM transport, MmpL3 has been an attractive therapeutic target and a key target for several preclinical agents. In 2019, the first crystal structures of the MmpL3 transporter and its complexes with lipids and inhibitors were reported. These structures revealed several unique structural features of MmpL3 and provided invaluable information on the mechanism of TMM transport. This review aims to highlight the recent advances made in the function of MmpL3 and summarises structural findings. The overall goal is to provide a mechanistic perspective of MmpL3-mediated lipid transport and inhibition, and to highlight the prospects for potential antituberculosis therapies.

Quantification of Natural Growth of Two Strains of Mycobacterium Marinum for Translational Antituberculosis Drug Development.

The zebrafish infected with Mycobacterium marinum (M. marinum) is an attractive tuberculosis disease model, showing similar pathogenesis to Mycobacterium tuberculosis (M. tuberculosis) infections in humans. To translate pharmacological findings from this disease model to higher vertebrates, a quantitative understanding of the natural growth of M. marinum in comparison to the natural growth of M. tuberculosis is essential. Here, the natural growth of two strains of M. marinum, E11 and MUSA, is studied over an extended period using an established model‐based approach, the multistate tuberculosis pharmacometric (MTP) model, for comparison to that of M. tuberculosis. Poikilotherm‐derived strain E11 and human‐derived strain MUSA were grown undisturbed up to 221 days and viability of cultures (colony forming unit (CFU)/mL) was determined by plating at different time points. Nonlinear mixed effects modeling using the MTP model quantified the bacterial growth, the transfer among fast, slow, and non‐multiplying states, and the inoculi. Both strains showed initial logistic growth, reaching a maximum after 20–25 days for E11 and MUSA, respectively, followed by a decrease to a new plateau. Natural growth of both E11 and MUSA was best described with Gompertz growth functions. For E11, the inoculum was best described in the slow‐multiplying state, for MUSA in the fast‐multiplying state. Natural growth of E11 was most similar to that of M. tuberculosis, whereas MUSA showed more aggressive growth behavior. Characterization of natural growth of M. marinum and quantitative comparison with M. tuberculosis brings the zebrafish tuberculosis disease model closer to the quantitative translational pipeline of antituberculosis drug development.

Expression and purification of soluble recombinant SapM from Mycobacterium tuberculosis

SapM from Mycobacterium tuberculosis is a secreted phosphatase critical for pathogen survival inside the host, representing an attractive target for the development of anti-tuberculosis drugs. The main limitation to biochemical and structural studies of SapM has been the lack of a suitable protocol to produce soluble recombinant protein. The aim of the present work was to produce SapM in Escherichia coli in a soluble and catalytically active form. We describe here the construct design, expression and purification of soluble SapM using Sarkosyl as a solubility-enhancing agent and auto-induction media. We demonstrate that solubilisation of the recombinant protein with Sarkosyl, and further purification, yields a catalytically active enzyme with high purity and monodisperse. The identity and molecular weight of the recombinant SapM was confirmed by mass spectrometry analyses, and we provide evidence that SapM behaves as a monomer in solution. Overall, this work lays the foundation for further studies to exploit SapM as a drug target, and provides a protocol for producing active and soluble recombinant enzymes that are hard to solubilise in E. coli.

MmpS5-MmpL5 Transporters Provide Mycobacterium smegmatis Resistance to imidazo[1,2-b][1,2,4,5]tetrazines.

The emergence and spread of drug-resistant Mycobacterium tuberculosis strains (including MDR, XDR, and TDR) force scientists worldwide to search for new anti-tuberculosis drugs. We have previously reported a number of imidazo[1,2-b][1,2,4,5]tetrazines–putative inhibitors of mycobacterial eukaryotic-type serine-threonine protein-kinases, active against M. tuberculosis. Whole genomic sequences of spontaneous drug-resistant M. smegmatis mutants revealed four genes possibly involved in imidazo[1,2-b][1,2,4,5]tetrazines resistance; however, the exact mechanism of resistance remain unknown. We used different approaches (construction of targeted mutants, overexpression of the wild-type (w.t.) and mutant genes, and gene-expression studies) to assess the role of the previously identified mutations. We show that mutations in MSMEG_1380 gene lead to overexpression of the mmpS5-mmpL5 operon in M. smegmatis, thus providing resistance to imidazo[1,2-b][1,2,4,5]tetrazines by increased efflux through the MmpS5-MmpL5 system, similarly to the mechanisms of resistance described for M. tuberculosis and M. abscessus. Mycobacterial MmpS5-MmpL5 transporters should be considered as an MDR-efflux system and they should be taken into account at early stages of anti-tuberculosis drug development.

Design, synthesis, and evaluation of new 2-(quinoline-4-yloxy)acetamide-based antituberculosis agents

Using a classical molecular simplification approach, a series of 36 quinolines were synthesized and evaluated as in vitro inhibitors of Mycobacterium tuberculosis (M. tuberculosis) growth. Structure–activity relationship (SAR) studies leaded to potent antitubercular agents, with minimum inhibitory concentration (MIC) values as low as 0.3 μM against M. tuberculosis H37Rv reference strain. Furthermore, the lead compounds were active against multidrug-resistant strains, without cross-resistance with some first- and second-line drugs. Testing the molecules against a spontaneous mutant strain containing a single mutation in the qcrB gene (T313A) indicated that the synthesized quinolines targeted the cytochrome bc1 complex. In addition, leading compounds were devoid of apparent toxicity to HepG2 and Vero cells and showed moderate elimination rates in human liver S9 fractions. Finally, the selected structures inhibited M. tuberculosis growth in a macrophage model of tuberculosis infection. Taken together, these data indicate that this class of compounds may furnish candidates for the future development of antituberculosis drugs.

Digging Deeper to Save the Old Anti-tuberculosis Target: D-Alanine-D-Alanine Ligase With a Novel Inhibitor, IMB-0283.

The emergence of drug-resistant Mycobacterium tuberculosis (Mtb) has hampered treatments for tuberculosis, which consequently now require novel agents to overcome such drug resistance. The genetically stable D-alanine–D-alanine ligase A (DdlA) has been deemed as an excellent therapeutic target for tuberculosis. In the present study, a competitive inhibitor (IMB-0283) of DdlA was obtained via high-throughput screening. The minimum inhibitory concentrations (MIC) of IMB-0283 for the standard and clinical drug-resistant Mtb strains ranged from 0.25 to 4.00 μg/mL, whereas the conventional inhibitor of DdlA, D-cycloserine (DCS), only inhibited the growth of the standard Mtb strain at 16 μg/mL. The lethal effect of IMB-0283 on Mtb was found to act intracellularly in a DdlA-dependent manner. Specifically, IMB-0283 prevented the synthesis of neonatal cell walls but did not damage mature cell walls. Compared with those of DCS, IMB-0283 exhibited lower cytotoxicity and a higher selective index (SI). At the same dosages of treatment, IMB-0283 reduced bacterial load (log CFU/mL) in an acute animal model from 5.58 to 4.40, while DCS did not yield any such treatment efficacy. Taken together, the lower cytotoxicity and more efficacious in vivo activity of IMB-0283 suggest that it is a promising lead compound for antituberculosis drug development.

Structural modification of a novel inhibitor for mycobacterium enoyl-acyl carrier protein reductase assisted by In silico structure-based drug screening.

Mycobacterium tuberculosis enoyl-acyl carrier protein reductase (mtInhA) is involved in the biosynthesis of mycolic acids, a major component of mycobacterial cell walls, and has been targeted in the development of anti-tuberculosis (TB) drugs. In our previous in silico structure-based drug screening study, we identified KES4, a novel class of mtInhA inhibitor. KES4 is composed of four ring structures (A-D-rings) and molecular dynamic simulation predicted that the D-ring is essential for the interaction with mtInhA. The structure-activity relationship study of the D-ring was attempted and aided by in silico docking simulations to improve the mtInhA inhibitory activity of KES4. A virtual chemical library of the D-ring-modified KES4 was then constructed and subjected to in silico docking simulation against mtInhA using the GOLD program. The candidate compound showing the highest GOLD score, referred to as KEN1, was synthesized, and its biological properties were compared with those of the lead compound KES4. We achieved the synthesis of KEN1 and evaluated its effects on InhA activity, mycobacterial growth, and cytotoxicity. The antimycobacterial activity of KEN1 was comparable to that of the lead compound (KES4), although it exhibited superior activity in mtInhA inhibition. \. We obtained a KES4 derivative with high mtInhA inhibitory activity by in silico docking simulation with a chemical library consisting of a series of D-ring-modified KES4.

Population Pharmacokinetics of Rifampicin on Pulmonary Tuberculosis Patients

Abstract: This study aimed to establish a reasonable population pharmacokinetic model for rifampicin taken orally by patients with pulmonary tuberculosis, estimate pharmacokinetic parameters as well as influencing covariates. Blood samples of patients were collected at day 10 – 14 after commencing treatment. Time – concentration data were handled using non-linear mixed-effect model with Monolix 2018. An one-compartment, linear elimination, absorption with transit compartments model was found to be the most suitable for rifampicin. Volume of distribution (33,5 L) and clearance (9,62 L) were found to be influenced by fat-free mass (calculated using Janmahasatian’s method). Absorption-related parameters (Ktr, mean transit time and Ka) were found to have high inter-individual variability.
 Keywords
 Rifampicin, population pharmacokinetics, pulmonary tuberculosis.
 References
 [1] Christian Lienhardt et al, Target regimen profiles for treatment of tuberculosis: a WHO document (2017).[2] J.G. Pasipanodya et al, Serum drug concentrations predictive of pulmonary tuberculosis outcomes, The Journal of infectious diseases 208(9) (2013) 1464-1473. https://doi.org/10.1093/infdis/jit352[3] Jonathan Reynolds, Scott K Heysell (2014), Understanding pharmacokinetics to improve tuberculosis treatment outcome, Expert opinion on drug metabolism & toxicology 10(6) (2014) 813-823. https://doi.org/10.1517/17425255.2014.895813[4] E.F. Egelund, A.B. Barth, C.A. Peloquin (2011), Population pharmacokinetics and its role in anti-tuberculosis drug development and optimization of treatment, Current pharmaceutical design 17(27) (2017) 2889-2899. https://doi.org/10.2174/138161211797470246.[5] J.F. Murray, D.E. Schraufnagel, P.C. Hopewell, Treatment of tuberculosis. A historical perspective, Annals of the American Thoracic Society 12(12) (2015) 1749-1759. https://doi.org/10.1513/AnnalsATS.201509-632PS[6] K.E. Stott, et al, Pharmacokinetics of rifampicin in adult TB patients and healthy volunteers: a systematic review and meta-analysis, Journal of Antimicrobial Chemotherapy 73(9) (2018) 2305-2313. https://doi.org/10.1093/jac/dky152.[7] Le Thi Luyen, Ta Manh Hung et al, Simultaneous Determination of Pyrazinamide, Rifampicin, Ethambutol, Isoniazid and Acetyl Isoniazid in Human Plasma by LC-MS/MS Method, Journal of Applied Pharmaceutical Science 8(09) (2018) 061-073. https://doi.org/ 10.7324/JAPS.2018.8910.[8] M.T. Chirehwa et al, Model-based evaluation of higher doses of rifampin using a semimechanistic model incorporating autoinduction and saturation of hepatic extraction, Antimicrobial agents and chemotherapy 60(1) (2016) 487-494. https://doi.org/10.1128/AAC.01830-15.[9] Paolo Denti et al, A population pharmacokinetic model for rifampicin auto-induction, The 3rd international workshop on clinical pharmacology of TB drugs (2010).[10] Y. Jing et al, Population pharmacokinetics of rifampicin in Chinese patients with pulmonary tuberculosis, The Journal of Clinical Pharmacology 56(5) (2016) 622-627. https://doi.org/10.1002/jcph.643.[11] S.R.C. Milán et al, Population pharmacokinetics of rifampicin in Mexican patients with tuberculosis, Journal of clinical pharmacy and therapeutics 38(1) (2013) 56-61. https://doi.org/10.1111/jcpt.12016.[12] Anushka Naidoo et al, Effects of genetic variability on rifampicin and isoniazid pharmacokinetics in South African patients with recurrent tuberculosis, Pharmacogenomics(00) (2013). https://doi.org/10.2217/pgs-2018-0166.[13] Neesha Rockwood et al, HIV-1 coinfection does not reduce exposure to rifampin, isoniazid, and pyrazinamide in South African tuberculosis outpatients, Antimicrobial agents and chemotherapy 60(10) (2016) 6050-6059. https://doi.org/10.1128/AAC.00480-16.[14] Alessandro Schipani et al, A simultaneous population pharmacokinetic analysis of rifampicin in Malawian adults and children, British Journal of Clinical Pharmacology 81(4) (2016) 679-687. https://doi.org/10.1111/bcp.12848.[15] Kok-Yong Seng et al, Population pharmacokinetics of rifampicin and 25-deacetyl-rifampicin in healthy Asian adults, Journal of Antimicrobial Chemotherapy 70(12) (2015) 3298-3306. https://doi.org/10.1093/jac/dkv268.[16] J.J. Wilkins et al, Population pharmacokinetics of rifampin in pulmonary tuberculosis patients, including a semimechanistic model to describe variable absorption, Antimicrobial agents and chemotherapy 52(6) (2008)2138-2148. https://dx.doi.org/10.1128%2FAAC.00461-07.[17] Sylvain Goutelle et al, Population modeling and Monte Carlo simulation study of the pharmacokinetics and antituberculosis pharmacodynamics of rifampin in lungs, Antimicrobial agents and chemotherapy 53(7) (2009) 2974-2981. https://doi.org/10.1128/AAC.01520-08.[18] R.M. Savic et al, Implementation of a transit compartment model for describing drug absorption in pharmacokinetic studies, Journal of pharmacokinetics and pharmacodynamics 34(5) (2007) 711-726. https://doi.org/10.1007/s10928-007-9066-0.[19] B.J. Anderson, N.H.G. Holford, Mechanism-based concepts of size and maturity in pharmacokinetics, Annu. Rev. Pharmacol. Toxicol 48 (2008) 303-332. https://doi.org/10.1146/annurev.pharmtox.48.113006.094708.[20] Kok-Yong Seng et al, Population pharmacokinetic analysis of isoniazid, acetyl-isoniazid and isonicotinic acid in healthy volunteers, Antimicrobial agents and chemotherapy, pp. AAC. (2015) 01244-15. https://doi.org/10.1128/AAC.01244-15.[21] Sarayut Janmahasatian et al, Quantification of lean bodyweight, Clinical pharmacokinetics 44(10), (2005) 1051-1065. https://doi.org/10.2165/00003088-200544100-00004.[22] Kidola Jeremiah et al, Nutritional supplementation increases rifampin exposure among tuberculosis patients coinfected with HIV, Antimicrobial agents and chemotherapy 58(6) (2014) 3468-3474. https://doi.org/10.1128/AAC.02307-13

Discovery of New and Potent InhA Inhibitors as Antituberculosis Agents: Structure-Based Virtual Screening Validated by Biological Assays and X-ray Crystallography.

The enoyl-acyl carrier protein reductase InhA of Mycobacterium tuberculosis is an attractive, validated target for antituberculosis drug development. Moreover, direct inhibitors of InhA remain effective against InhA variants with mutations associated with isoniazid resistance, offering the potential for activity against MDR isolates. Here, structure-based virtual screening supported by biological assays was applied to identify novel InhA inhibitors as potential antituberculosis agents. High-speed Glide SP docking was initially performed against two conformations of InhA differing in the orientation of the active site Tyr158. The resulting hits were filtered for drug-likeness based on Lipinski's rule and avoidance of PAINS-like properties and finally subjected to Glide XP docking to improve accuracy. Sixteen compounds were identified and selected for in vitro biological assays, of which two (compounds 1 and 7) showed MIC of 12.5 and 25 μg/mL against M. tuberculosis H37Rv, respectively. Inhibition assays against purified recombinant InhA determined IC50 values for these compounds of 0.38 and 0.22 μM, respectively. A crystal structure of the most potent compound, compound 7, bound to InhA revealed the inhibitor to occupy a hydrophobic pocket implicated in binding the aliphatic portions of InhA substrates but distant from the NADH cofactor, i.e., in a site distinct from those occupied by the great majority of known InhA inhibitors. This compound provides an attractive starting template for ligand optimization aimed at discovery of new and effective compounds against M. tuberculosis that act by targeting InhA.

Development of new antituberculosis drugs among of 1,3- and 1,4-diazines. Highlights and perspectives

The properties of pyrimidine and pyrazine derivatives responsible for the existence of antituberculosis activity are considered. Examples of synthesis and biological activity of the most promising compounds containing the pyrimidine or pyrazine rings in the molecular structure are presented.

Directions for research and development of anti-tuberculosis drugs

The increasing incidence of new cases of tuberculosis, of latent forms and with multiple and extended resistance, required the acceleration of the research and elaboration of the anti-tuberculosis drugs by elucidating new targets. The main directions of study of the new compounds focused on the influence on the cell wall, the synthesis of proteins and nucleic acids, the energy metabolism, as well as on the immune status of the host. At the base of these strategies were the data regarding the structural components and the particularities of the life cycle of mycobacteria at different stages of disease evolution.

Transport mechanism of Mycobacterium tuberculosis MmpL/S family proteins and implications in pharmaceutical targeting.

Tuberculosis caused by Mycobacterium tuberculosis remains a serious threat to public health. The M. tuberculosis cell envelope is closely related to its virulence and drug resistance. Mycobacterial membrane large proteins (MmpL) are lipid-transporting proteins of the efflux pump resistance nodulation cell division (RND) superfamily with lipid substrate specificity and non-transport lipid function. Mycobacterial membrane small proteins (MmpS) are small regulatory proteins, and they are also responsible for some virulence-related effects as accessory proteins of MmpL. The MmpL transporters are the candidate targets for the development of anti-tuberculosis drugs. This article summarizes the structure, function, phylogenetics of M. tuberculosis MmpL/S proteins and their roles in host immune response, inhibitors and regulatory system.

Derailing the aspartate pathway of Mycobacterium tuberculosis to eradicate persistent infection

A major constraint for developing new anti-tuberculosis drugs is the limited number of validated targets that allow eradication of persistent infections. Here, we uncover a vulnerable component of Mycobacterium tuberculosis (Mtb) persistence metabolism, the aspartate pathway. Rapid death of threonine and homoserine auxotrophs points to a distinct susceptibility of Mtb to inhibition of this pathway. Combinatorial metabolomic and transcriptomic analysis reveals that inability to produce threonine leads to deregulation of aspartate kinase, causing flux imbalance and lysine and DAP accumulation. Mtb’s adaptive response to this metabolic stress involves a relief valve-like mechanism combining lysine export and catabolism via aminoadipate. We present evidence that inhibition of the aspartate pathway at different branch-point enzymes leads to clearance of chronic infections. Together these findings demonstrate that the aspartate pathway in Mtb relies on a combination of metabolic control mechanisms, is required for persistence, and represents a target space for anti-tuberculosis drug development.