anti-TB Activity Research Articles

Total synthesis, structure elucidation and expanded bioactivity of icosalide A: effect of lipophilicity and ester to amide substitution on its bioactivity.

The first total synthesis of icosalide A, an antibacterial depsipeptide that is unique in that it contains two lipophilic beta-hydroxy acids, has been achieved by following Fmoc solid-phase peptide synthesis in combination with solution-phase synthesis. The ambiguity in the absolute stereochemistry of icosalide A has been resolved by synthesizing the reported structures and other relevant diastereomers of icosalides and comparing their NMR data. NMR-based structure elucidation of icosalide A revealed a well-folded structure with cross-strand hydrogen bonds similar to the anti-parallel beta-sheet conformation in peptides and displayed a synergistic juxtaposition of the aliphatic sidechains. 12 analogues of icosalide A were synthesized by varying the constituent lipophilic beta-hydroxy acid residues, and their biological activities against Bacillus thuringiensis and Paenibacillus dendritiformis were explored. Most of these icosalide analogues showed an MIC of 12.5 μg mL-1 against both bacteria. Swarming inhibition by icosalides was least in B. thuringiensis (8.3%) compared to that in P. dendritiformis (33%). Furthermore, this is the first report of icosalides showing assured inhibitory action (MIC between 2 and 10 μg mL-1) against the active stage of Mycobacterium tuberculosis and cancer cell lines such as HeLa and ThP1. This study could help optimize icosalides for anti-TB, antibacterial, and anti-cancer activities.

Design, synthesis and biological evaluation of phenanthridine amide and 1,2,3-triazole analogues against Mycobacterium tuberculosis.

The phenanthridine core exhibits antitubercular activity, according to reports from the literature. Several 1,2,3-triazole-based heterocyclic compounds are well-known antitubercular agents. A series of twenty-five phenanthridine amide and 1,2,3-triazole derivatives are synthesized and analyzed using ESI-MS, 1HNMR, and 13CNMR on the basis of our earlier findings that phenanthridine and 1,2,3-triazoles shown good antitubercular activity. The synthesized phenanthridine amide and 1,2,3-triazole analogues were tested in vitro against Mycobacterium tuberculosis H37Rv and minimum inhibitory concentration (MIC) values were determined utilizing non-replicating and replicating low-oxygen recovery assay (LORA) and microplate Alamar Blue assay (MABA) methodologies. The phenanthridine amide derivative PA-01 had an MIC of 61.31 μM in MABA and 62.09 μM in the LORA technique, showing intense anti-TB activity. Amongst the phenanthridine triazole derivatives, PT-09, with MICs of 41.47 and 78.75 μM against the tested strain of Mtb in both MABA and LORA was the most active one. The final analogues' drug-likeness is predicted using absorption, distribution, metabolism, excretion, and toxicity (ADMET) studies. The most active compounds PA-01 and PT-09 were further subjected to in silico docking studies. Using the Glide module of Schrodinger, molecular docking analysis was carried out to estimate the plausible binding pattern of PA-01 and PT-09 at the active site of Mycobacterial DNA topoisomerase II (PDB code: 5BS8). Further, molecular dynamics studies of PA-01 and PT-09 were also carried out.

QSAR Studies, Molecular Docking, Molecular Dynamics, Synthesis, and Biological Evaluation of Novel Quinolinone-Based Thiosemicarbazones against Mycobacterium tuberculosis.

In this study, a series of novel quinolinone-based thiosemicarbazones were designed in silico and their activities tested in vitro against Mycobacterium tuberculosis (M. tuberculosis). Quantitative structure-activity relationship (QSAR) studies were performed using quinolinone and thiosemicarbazide as pharmacophoric nuclei; the best model showed statistical parameters of R2 = 0.83; F = 47.96; s = 0.31, and was validated by several different methods. The van der Waals volume, electron density, and electronegativity model results suggested a pivotal role in antituberculosis (anti-TB) activity. Subsequently, from this model a new series of quinolinone-thiosemicarbazone 11a-e was designed and docked against two tuberculosis protein targets: enoyl-acyl carrier protein reductase (InhA) and decaprenylphosphoryl-β-D-ribose-2'-oxidase (DprE1). Molecular dynamics simulation over 200 ns showed a binding energy of -71.3 to -12.7 Kcal/mol, suggesting likely inhibition. In vitro antimycobacterial activity of quinolinone-thiosemicarbazone for 11a-e was evaluated against M. bovis, M. tuberculosis H37Rv, and six different strains of drug-resistant M. tuberculosis. All compounds exhibited good to excellent activity against all the families of M. tuberculosis. Several of the here synthesized compounds were more effective than the standard drugs (isoniazid, oxafloxacin), 11d and 11e being the most active products. The results suggest that these compounds may contribute as lead compounds in the research of new potential antimycobacterial agents.

Synthesis, crystal structure, electronic structure, and anti-tubercular properties of two new coumarin derivatives bearing theophylline moiety

In this work, synthesis, crystal and electronic structure of newly synthesized coumarin-theophylline hybrids exhibiting high anti-TB activity were investigated by experiments and quantum chemical calculations. The molecular structure determined by single crystal X-ray diffraction method revealed that the compound crystalize in the monoclinic system with the space group P21/c. The molecule is stabilized by strong and weak intra-/inter-molecular hydrogen bonds. The crystal structure compares well with the optimized geometry calculated at B3LYP/6–311++G(d,p) level by using density functional theory. The electronic structure of the compound has been explored by investigating frontier molecular orbitals, natural atomic charges, natural populations of the molecular orbitals, Hirshfeld and molecular electrostatic potential surfaces. It is realized that the compounds show substantial in vitro anti-tuberculosis activity with the MTBH37Rv strain and were identified as a hit candidate, exhibiting MIC of 0.39 & 0.78 µg/mL against Mycobacterium tuberculosis.

New tetrahydropyrimidine-1,2,3-triazole clubbed compounds: Antitubercular activity and Thymidine Monophosphate Kinase (TMPKmt) inhibition

Two series of new tetrahydropyrimidine (THPM)-1,2,3-triazole clubbed compounds were designed, synthesized and screened for their antitubercular (anti-TB) activity against M. tuberculosis H37Rv strain using microplate alamar blue assay (MABA). The most active compounds 5c, 5d, 5e and 5f were further examined for their cytotoxicity against the growth of RAW 264.7 mouse macrophage cells using MTT assay. The four compounds showed safety profiles better than or comparable to that of ethambutol (EMB). These compounds were evaluated for their inhibition activity against mycobacterium tuberculosis thymidine monophosphate kinase (TMPKmt). Compounds 5c and 5e were the most potent exhibiting comparable inhibition activity to that of the natural substrate deoxythymidine monophosphate (dTMP). An in silico study was performed including docking of the most active compounds 5c and 5e into the TMPKmt (PDB: ID 1G3U) binding pocket in addition to prediction of their physicochemical and pharmacokinetic properties to explore the overall activity of these anti-TB candidates. Compounds 5c and 5e are promising anti-TB agents and TMPKmt inhibitors with acceptable oral bioavailability, physicochemical and pharmacokinetic properties.

In Vitro Antimycobacterial Activity of Human Lactoferrin-Derived Peptide, D-hLF 1-11, against Susceptible and Drug-Resistant Mycobacterium tuberculosis and Its Synergistic Effect with Rifampicin.

Tuberculosis is a highly contagious disease caused by the Mycobacterium tuberculosis complex (MTBC). Although TB is treatable, multidrug-resistant, extensively drug-resistant, and totally drug-resistant forms of M. tuberculosis have become a new life-threatening concern. New anti-TB drugs that are capable of curing these drug-resistant strains are urgently needed. The purpose of this study is to determine the antimycobacterial activity of D-enantiomer human lactoferricin 1-11 (D-hLF 1-11) against mycobacteria in vitro using a 3-(4,5-dimethylthiazol-2-yl)-2,5-dephenyltetrazolium bromide colorimetric assay, resazurin microplate assay, and microscopic observation drug susceptibility assay. Three previously described antimicrobial peptides, protegrin-1, AK 15-6, and melittin, with potent anti-TB activity, were included in this study. The findings suggest that D-hLF 1-11 can inhibit the growth of M. tuberculosis with a minimum inhibitory concentration of 100-200 µg/mL in susceptible, isoniazid (INH)-monoresistant, rifampicin (RF)-monoresistant, and MDR strains. The peptide can also inhibit some nontuberculous mycobacteria and other MTBC in similar concentrations. The antibiofilm activity of D-hLF 1-11 against the biofilm-forming M. abscessus was determined by crystal violet staining, and no significant difference is observed between the treated and untreated biofilm control. The checkerboard assay was subsequently carried out with M. tuberculosis H37Rv and the results indicate that D-hLF 1-11 displays an additive effect when combined with INH and a synergistic effect when combined with RF, with fractional inhibitory concentration indices of 0.730 and 0.312, respectively. The red blood cell hemolytic assay was initially applied for the toxicity determination of D-hLF 1-11, and negligible hemolysis (<1%) was observed, despite a concentration of up to 4 mg/mL being evaluated. Overall, D-hLF 1-11 has potential as a novel antimycobacterial agent for the future treatment of drug-sensitive and drug-resistant M. tuberculosis infections.

Ethionamide and Prothionamide Based Coumarinyl-Thiazole Derivatives: Synthesis, Antitubercular Activity, Toxicity Investigations and Molecular Docking Studies.

The goal of this research work was to prepare and evaluate the antitubercular (anti-TB) activity of ethionamide (ETH) and prothionamide (PTH) based coumarinyl-thiazole derivatives. ETH and PTH were reacted with coumarin intermediates (3a-3e) to provide the target compounds (4a-4e and 4f-4j, respectively). Spectral studies confirmed the assigned structures of 4a-4j. The Microplate Alamar Blue Assay was utilized to evaluate the anti-TB activity of compounds 4a-4j against Mycobacterium tuberculosis H37Rv strain in comparison to ETH, PTH, isoniazid (INH), and pyrazinamide (PYZ) as standard drugs. The cytotoxicity studies were carried out versus HepG2 and Vero cell lines. In addition. molecular docking studies of 4a-4j concerning the DprE1 enzyme and the in-silico evaluation of physicochemical and pharmacokinetic parameters were performed. Compounds 4a, 4b, 4f, and 4g displayed equal minimum inhibitory concentration (MIC) values in comparison to INH (3.125 μg/ml) and PYZ (3.125 μg/ml), whereas 4c-4e and 4h-4j displayed better MIC values (1.562 μg/mL) than INH and PYZ. All compounds presented better anti-TB potential than ETH (6.25 μg/mL) and PTH (6.25 μg/mL). The studies of toxicity revealed that 4a-4j were safe up to 300 μg/mL concentration versus Vero and HepG2 cell lines. The molecular docking studies suggested that 4a-4j could possess anti-TB activity through the inhibition of the DprE1 enzyme. The in silico studies showed that 4a-4j followed Lipinski's rule (drug-likeliness) and exhibited better gastrointestinal absorption than BTZ043 and macozinone. In conclusion, the ETH and PTH-based coumarinyl-thiazole template can help developing selective DprE1 enzyme inhibitors as potent anti-TB agents.

Silver nanoparticles as a nanoprobe for trace level simultaneous detection of streptomycin sulfate and isoniazid and anti-TB activity of their nanoparticles complexes

A facile method was developed for the simultaneous detection of two anti-TB drugs (i.e., streptomycin sulfate and isoniazid) by using maltol capped silver nanoparticles (McAgNPs) as a chemosensor. The interaction between anti-TB drugs and McAgNPs depends on aggregation due to the electrostatic interaction and involvement of an amine group in the formation of a drug nanoparticles complex. The colorimetric change from yellow to pink was observed when McAgNPs interact with streptomycin sulfate (STR.SO4) and leads to the surface plasmon resonance (SPR) quenching at 436 nm followed by a red shift at 664 nm. While interaction of isoniazid (INH) with McAgNPs produced a minor change in color intensity (light to dark yellow) with significant enhancement in SPR at 436 nm. A good linear relationship was observed in terms of drug concentrations (i.e., 0.04–100 and 0.1–100 µM), and the limit of detections (i.e., 0.044 and 0.045 µM) for STR.SO4 and INH, respectively. The proposed method was also validated in environmental, biological and pharmaceutical samples with excellent recovery rates. For practical applicability, the combination of McAgNPs with STR.SO4 and INH were successfully tested against Mycobacterium tuberculosis (MTB) sensitive strain (H37Rv). Obtained results showed that McAgNPs-drug complexes inhibited MTB significantly far below the critical concentrations of the drugs. Hence, McAgNPs not only have great potential as a dual sensor but also their complexes with STR.SO4 and INH for TB treatment.

Degradation of Polymer-Drug Conjugate Nanoparticles Based on Lactic and Itaconic Acid.

Tuberculosis (TB) is still a significant threat to human health. A promising solution is engineering nanoparticulate drug carriers to deliver anti-TB molecules. Itaconic acid (ITA) potentially has anti-TB activity; however, its incorporation in nanoparticles (NP) is challenging. Here we show an approach for preparing polymer-ITA conjugate NPs and a methodology for investigating the NP degradation and ITA release mechanism. The conjugate was synthesized by the two-directional growing of polylactic acid (PLA) chains, followed by capping their extremities with ITA. The poly(lactate)-itaconate PLA-ITA was then used to formulate NPs. The degradation and drug release processes of the polymer conjugate NPs were studied qualitatively and quantitatively. The molecular structures of released species were characterized by using liquid NMR spectroscopy and mass spectrometry. We discovered a complex NP hydrolysis process forming diverse oligomers, as well as monomeric lactic acid (LA) and drug ITA. The slow degradation process led to a low release of free drugs, although raising the pH from 5.3 to 7.4 induced a slight increase in the amounts of released products. TEM images showed that bulk erosion is likely to play the primary role in the degradation of PLA-ITA NPs. The overall results and methodology can be of interest for understanding the mechanisms of NP degradation and drug release of this new polymer-drug conjugate system.

MmpL3 Inhibition as a Promising Approach to Develop Novel Therapies against Tuberculosis: A Spotlight on SQ109, Clinical Studies, and Patents Literature.

Tuberculosis (TB) is accountable for considerable global morbidity and mortality. Effective TB therapy with multiple drugs completes in about six months. The longer duration of TB therapy challenges patient compliance and contributes to treatment collapse and drug resistance (DR) progress. Therefore, new medications with an innovative mechanism of action are desperately required to shorten the TB therapy's duration and effective TB control. The mycobacterial membrane protein Large 3 (MmpL3) is a novel, mycobacteria-conserved and recognized promiscuous drug target used in the development of better treatments for multi-drug resistance TB (MDR-TB) and extensively drug-resistant TB (XDR-TB). This article spotlights MmpL3, the clinical studies of its inhibitor (SQ109), and the patent literature. The literature on MmpL3 inhibitors was searched on PubMed and freely available patent databases (Espacenet, USPTO, and PatentScope). SQ109, an analog of ethambutol (EMB), is an established MmpL3 inhibitor and has completed Phase 2b-3 clinical trials. Infectex and Sequella are developing orally active SQ109 in partnership to treat MDR pulmonary TB. SQ109 has demonstrated activity against drug-sensitive (DS) and drug-resistant (DR) Mycobacterium tuberculosis (Mtb) and a synergistic effect with isoniazid (INH), rifampicin (RIF), clofazimine (CFZ), and bedaquiline (BNQ). The combination of SQ109, clofazimine, bedaquiline, and pyrazinamide (PZA) has been patented due to its excellent anti-TB activity against MDR-TB, XDR-TB, and latent-TB. The combinations of SQ109 with other anti-TB drugs (chloroquine, hydroxychloroquine, and sutezolid) have also been claimed in the patent literature. SQ109 is more potent than EMB and could substitute EMB in the intensive stage of TB treatment with the three- or four-drug combination. Developing MmpL3 inhibitors is a promising approach to fighting the challenges associated with DS-TB and DR-TB. The authors foresee MmpL3 inhibitors such as SQ109 as future drugs for TB treatment.

Molecular modelling investigation on 4-aminoquinoline derivatives as potent anti-tubercular agents

The emergency of new Mycobacterium tuberculosis strains leads to multi-drug resistant tuberculosis (MDR) and total drug resistant tuberculosis (TDR) indicating the urgency in the development of newer anti-tubercular agents to be effective against the resistance strains. In the present study pharmacophore modelling and atom-based 3D-QSAR of 4-Aminoquinoline derivatives was carried out to understand the key structural features responsible for anti-tb activity. Phase module of Schrödinger was used to generate a five-point Pharmacophore for 46 molecules belonging to 4-Aminoquinolines. The best scoring hypothesis (ADHHR_1) had one H-bond Acceptor (A1), one H-bond donor (D5), two Hydrophobic regions (H10 and H11) and one Ring (R14) with a good regression coefficient of 0.9604. The validity of the hypothesis was judged by the cross-validation coefficient (Q2= 0.7885) and Pearson- r (0.9158) followed by the external validation which showed high predictive power. Newer molecules were designed and subjected to molecular docking to explore the alleged binding modes followed by molecular dynamic simulation studies. The molecular modelling study revealed the significance of aromatic ring and hydrogen bond responsible for potent anti-tb activity.

Synthesis, Characterization, DFT Analysis, Biological Evaluation, and Molecular Docking of Schiff Base Derived from Isatin–Isoniazid and Its Metal (II) Complexes

A series of octahedral Zn(II), Cu(II), Ni(II), and Co(II) complexes have been synthesized with ONO donor Schiff base ligand N'-(6-chloro-2-oxoindolin-3-ylidene)nicotinohydrazide (3) derived from the reaction of 6-chloro isatin (1) and isoniazid (2). The chemical structures of the compounds were elucidated by spectral and physicochemical techniques. The spectral data reveal the octahedral geometry for all the metal (II) complexes. The compounds were screened for their antibacterial and antifungal activity; all the metal (II) complexes exhibited enhanced activity. The Cu(II) and Co(II) complexes displayed equipotent anti-TB activity when evaluated with standard Ciprofloxacin. Furthermore, the Ni(II) and Co(II) complexes showed excellent antioxidant activity compared to the standard drug. Density Functional Theory (DFT) estimations for ligand (3) at the DFT/B3LYP level via 6-31 G++ (d, p) replicate the structure and geometry. Finally, HOMO and LUMO analysis was used for the charge transfer interface of the structure. The Cu(II), Ni(II), and Co(II) complexes exhibited good docking properties in molecular docking studies against Cytochrome c Peroxidase (2 × 08).

Nosiheptide Harbors Potent In Vitro and Intracellular Inhbitory Activities against Mycobacterium tuberculosis.

Multidrug-resistant tuberculosis (MDR-TB) is often associated with poor clinical outcomes. In this study, we evaluated the potential of nosiheptide (NOS) as a new drug candidate for treating Mycobacterium tuberculosis infections, including MDR-TB. The antimicrobial susceptibility testing was performed to determine the MICs of NOS against 18 reference strains of slowly growing mycobacteria (SGM) and 128 clinical isolates of M. tuberculosis. The postantibiotic effects (PAE) and interaction with other antituberculosis drugs of NOS were also evaluated using M. tuberculosis H37Rv. Fifteen out of the 18 tested reference strains of SGM had MICs far below 1 μg/mL. From the 128 M. tuberculosis clinical isolates, the MIC50 and MIC90 were 0.25 μg/mL and 1 μg/mL, respectively; the tentative epidemiological cutoff (ECOFF) was defined at 1 μg/mL. Furthermore, a Lys89Thr mutation was found in one M. tuberculosis isolate with a MIC of NOS >8 μg/mL. After 24 h of incubation, NOS at 1 μg/mL inhibited 25.79 ± 1.22% of intracellular bacterial growth, which was comparable with the inhibitory rate of 25.71 ± 3.67% achieved by rifampin at 2 μg/mL. Compared to rifampicin and isoniazid (INH), NOS had a much longer PAE, i.e., a value of about 16 days. In addition, a partial synergy between NOS and INH was observed. NOS has potent inhibitory activities against M. tuberculosis in vitro as well as in macrophages. Furthermore, the long PAE and partial synergistic effect with INH, in addition to the added safety of long-term use as a feed additive in husbandry, provide support for NOS being a promising drug candidate for tuberculosis treatment. IMPORTANCE This study is aimed at chemotherapy for MDR-TB, mainly to explore the anti-TB activity of the existing chemotherapeutic reagent. We found that NOS has potent inhibitory activities against M. tuberculosis in vitro regardless of the drug-resistant profile. Furthermore, NOS also showed the long PAE and partial synergistic effect with INH and is nontoxic, providing support for its promise as a drug candidate for drug-resistant tuberculosis treatment.

Design, synthesis and characterization of novel Benzothiazolyl pyrazoles as potential antitubercular scaffold

The present study validates the synthesis of two new series of benzothiazole conjugated pyrazole analogs by the coupling of benzothiazole hydrazine with 4-formyl pyrazole derivatives, which was set up by Vilsmeier-Haack reaction. The synthetic approach was initiated by coupling different acetophenones and phenyl hydrazine to synthesize the Schiff's bases, which further undergo cyclization with Vilsmeier-Haack reagent followed by the imine formation. A singlet at 7.1 ppm in 1 H NMR indicated the protons of azo methane linkage (Schiff's base formation). Synthesized compounds were characterized by FT-IR, LC-MS, 1 H NMR and 13 C NMR spectroscopic techniques. The peak at 1593 cm −1 (>C=N-) indicated the formation of the azo methane linkage in the synthesized compounds. In 1 H NMR spectroscopy, a singlet peak at 8.89 ppm indicated the pyrazole proton, which confirmed the presence of 5-membered pyrazole ring.The recently synthesized compounds were screened for the anticancer and anti-tubercular (anti-TB) activities. MIC values of the compounds for in-vitro anti-TB activity were 1.6 μg/ml and MIC value of the compounds for in-vitro anti-cancer activities were 67.65 µg/ml and 70.31 µg/ml, against HELA and KB cell lines respectively. Most active compounds were found to be less toxic, which was determined by MTT assay method with normal cell line (L292). Biological screening of the synthesized series of compounds reveals that, Compound 5b was the potent molecule. .

Determination of anti-tuberculosis activity of biosynthesized gold nanocompounds against M. tuberculosis H37RV

BackgroundThe biosynthesis of gold nanoparticles using medicinal plants as reducing and stabilizing agent for synthesis is an emerging area of research due to their cost effectiveness and further diversified applications in various fields. People with HIV are prone to these opportunistic infections like TB due to the immunocompromised condition. In the present study, the nanoparticles and nanoconjugates were screened for effective anti-mycobacterial efficiency against opportunistic infections. MethodsIncidentally, the nanoparticles were biosynthesized using single plant extract. The biosynthesized nanoparticles were initially screened for effective anti-tuberculosis activity against Mycobacterium tuberculosis. Based on the effective antimicrobial activity, a nanoconjugate was biosynthesized combining three plant extracts for a cumulative activity. ResultsThe biosynthesized gold nanoparticles and nanoconjugates showed MIC demonstrating for 99% inhibition and MIC99 was found to be 6.42 μg/ml. Among all the 15 nanoparticles tested, seven NPs showed exceptional anti-TB activities NP1, NP2, NP6, NP7, NP10, NP12 and NP15 and the other nanoparticles exhibited varying degrees of inhibition - anti-TB activities. In the 12 nanoconjugate tested, seven nanoconjugate demonstrated exceptional anti-TB activities such as NCC1, NCC2, NCC5, NCC6, NCV1, NCV6 and NCV4. ConclusionThe objective of the study was to identify the nanoparticles and nanoconjugates which demonstrated potential activity against M. tuberculosis so that a single nanoparticle or nanoconjugate can be targeted to treat patients with TB. Minimum Inhibitory Concentration (MIC) of the biosynthesized gold nanoparticles and nanoconjugates were determined against M. tuberculosis H37Rv.

Bacterial FtsZ inhibition by benzo[d]imidazole-2-carboxamide derivative with anti-TB activity.

Aims: The present study aimed to assess the mode of action of previously reported anti-Mycobacterium tuberculosis benzo[d]imidazole-2-carboxamides against FtsZ along with their antibacterial potential. Materials & methods: The anti-mycobacterial action of benzo[d]imidazole-2-carboxamides against FtsZ was evaluated using inhibition of Bacillus subtilis 168, light scattering assay, circular dichroism spectroscopy, in silico molecular docking and molecular dynamics simulations. Results & conclusion: Three compounds (1k, 1o and 1e) were active against isoniazid-resistant strains. Four compounds (1h, 1i, 1o and 4h) showed >70% inhibition against B. subtilis 168. Compound 1o was the most potent inhibitor (91±5% inhibition) ofB. subtilis 168 FtsZ and perturbed its secondary structure. Molecular docking and molecular dynamics simulation of complexed 1o suggested M. tuberculosis FtsZ as a possible target for antitubercular activity.

Molecular Interplay between Vitamin D and Immunity can Aid Antitubercular Treatment Vitamin D in Immunomodulation of TB

Tuberculosis (TB) causes maximum mortality and morbidity worldwide. 25 per cent of the global population harbour Mycobacterium tuberculosis (Mtb) and therefore are at risk of developing active disease. Of late, the disseminated diseases of TB are on the increase. Nearly one-third of all TB infections can be classified as extrapulmonary-TB (EPTB). TB can spread to the bone, brain, intestine, peritoneum, genitourinary system, and female genital sites leading to problems of conception. Therefore undoubtedly, TB has turned out to be a tremendous public health problem globally. The emergence of drug-resistant bacteria calls for new anti-tuberculous drugs to enhance response to antimicrobial therapy for active TB. However, discoveries of very effective anti-TB new medicines have not materialised yet. Thus, nutritional anti-TB intervention is highly important. In the pre-antibiotic era, Vitamin D was used for the treatment of TB. Its active component 1,25-dihydroxy-vitamin D3 was shown to display anti-TB activity in vitro. Vitamin D deficient humans display greater susceptibility to TB. Vitamin D deficiency induces worse disease progression in TB cases as observed in many clinical trials. The efficacy of the addition of vitamin D supplements in TB treatment has also been estimated. Thus, by now, the role of vitamin D in TB prevention and treatment is well established. Knowledge of the molecular mechanism of vitamin D is crucially vital for new anti-TB drug design. This review article discusses the recent advancement regarding the molecular mechanism of vitamin D-related anti-TB action. Further elucidation of this area may help novel anti-TB drug development.

Molecular Insight into Mycobacterium tuberculosis Resistance to Nitrofuranyl Amides Gained through Metagenomics-like Analysis of Spontaneous Mutants.

We performed synthesis of new nitrofuranyl amides and investigated their anti-TB activity and primary genetic response of mycobacteria through whole-genome sequencing (WGS) of spontaneous resistant mutants. The in vitro activity was assessed on reference strain Mycobacterium tuberculosis H37Rv. The most active compound 11 was used for in vitro selection of spontaneous resistant mutants. The same mutations in six genes were detected in bacterial cultures grown under increased concentrations of 11 (2×, 4×, 8× MIC). The mutant positions were presented as mixed wild type and mutant alleles while increasing the concentration of the compound led to the semi-proportional and significant increase in mutant alleles. The identified genes belong to different categories and pathways. Some of them were previously reported as mediating drug resistance or drug tolerance, and counteracting oxidative and nitrosative stress, in particular: Rv0224c, fbiC, iniA, and Rv1592c. Gene-set interaction analysis revealed a certain weak interaction for gene pairs Rv1592–Rv1639c and Rv1592–Rv0224c. To conclude, this study experimentally demonstrated a multifaceted primary genetic response of M. tuberculosis to the action of nitrofurans. All three 11-treated subcultures independently presented the same six SNPs, which suggests their non-random occurrence and likely causative relationship between compound action and possible resistance mechanism.

Novel diaryl ether derivatives as InhA inhibitors: Design, synthesis and antimycobacterial activity

A new series of triclosan (TCL)-mimicking diaryl ether derivatives 7–25 were synthesized and evaluated as inhibitors of enoyl acyl carrier protein reductase InhA enzyme. In addition, these derivatives were screened as inhibitors of drug-susceptible (DS), multidrug-resistant (MDR), and extensive drug-resistant (XDR) Mycobacterium tuberculosis (MTB) strains. Most compounds exihibted superior anti-TB activities and improved ClogP compared to TCL as a standard drug. The present work has led to the identification of compounds 14, 19 and 24 which possess remarkable activities against DS, MDR and XDR MTB strains with MIC values of 1.95, 3.9 and 15.63 µg/ml, respectively for compound 14, 1.95, 3.9 and 7.81 µg/ml, respectively for compound 19 and 0.98, 1.95 and 3.9 µg/ml, respectively for compound 24. Most compounds did not exhibit toxicity to HePG2 normal cell line. Compounds 14, 19 and 24, presenting the best MIC values, were further evaluated as inhibitors of InhA enzyme. They showed high binding affinities in the micromolar range with IC50 values of 1.33, 0.6, and 0.29 µM for compounds 14, 19, and 24, respectively. Furthermore, molecular docking approach was utilized to understand the difference in bioactivities between the new compounds. In particular, the results revealed strong binding interactions and high docking scores of compounds 14, 19 and 24, which could correlate with their high activities. Mainly, the molecular modelling study of compound 24 provides an excellent platform for understanding the molecular mechanism regarding InhA inhibition. Thus, compound 24 could be a lead compound for future development of new antitubercular drugs.

Design and synthesis of novel quinazolinyl-bisspirooxindoles as potent anti-tubercular agents: an ultrasound-promoted methodology.

The essential need for the potent anti-tubercular (anti-TB) agents with high selectivity and safety profile prompted us to synthesize a new series of quinazolinyl-bisspirooxindoles. The title compounds were synthesized by one-pot multicomponent [3 + 2] cycloaddition reaction under ultrasonication. Further, in vitro anti-TB activity was evaluated against Mycobacterium tuberculosis H37Rv. Among the screened compounds, two compounds (4q and 4x) showed potent activity with MIC value 1.56µg/mL and four compounds exhibited significant activity (MIC = 3.125µg/mL), and also cytotoxicity studies against RAW 264.7 cell lines reveal that most active compounds were less toxic to humans. In addition, in order to demonstrate the inhibitory properties, molecular docking studies were carried out and the results showed that the target compounds have good binding energy and better binding affinity within the active pocket, thus these compounds may consider to be as potent inhibitors toward selective targets.