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.

Variations in the C-unit of bedaquiline provides analogues with improved biology and pharmacology.

Analogues of the anti-tuberculosis drug bedaquiline, bearing a 3,5-dimethoxy-4-pyridyl C-unit, retain high anti-bacterial potency yet exert less inhibition of the hERG potassium channel, in vitro, than the parent compound. Two of these analogues (TBAJ-587 and TBAJ-876) are now in preclinical development. The present study further explores structure-activity relationships across a range of related 3,5-disubstituted-4-pyridyl C-unit bedaquiline analogues of greatly varying lipophilicity (clogP from 8.16 to 1.89). This broader class shows similar properties to the 3,5-dimethoxy-4-pyridyl series, being substantially more potent in vitro and equally active in an in vivo (mouse) model than bedaquiline, while retaining a lower cardiovascular risk profile through greatly attenuated hERG inhibition.

3,5-Dialkoxypyridine analogues of bedaquiline are potent antituberculosis agents with minimal inhibition of the hERG channel.

Bedaquiline is a new drug of the diarylquinoline class that has proven to be clinically effective against drug-resistant tuberculosis, but has a cardiac liability (prolongation of the QT interval) due to its potent inhibition of the cardiac potassium channel protein hERG. Bedaquiline is highly lipophilic and has an extremely long terminal half-life, so has the potential for more-than-desired accumulation in tissues during the relatively long treatment durations required to cure TB. The present work is part of a program that seeks to identify a diarylquinoline that is as potent as bedaquiline against Mycobacterium tuberculosis, with lower lipophilicity, higher clearance, and lower risk for QT prolongation. Previous work led to the identification of compounds with greatly-reduced lipophilicity compounds that retain good anti-tubercular activity in vitro and in mouse models of TB, but has not addressed the hERG blockade. We now present compounds where the C-unit naphthalene is replaced by a 3,5-dialkoxy-4-pyridyl, demonstrate more potent in vitro and in vivo anti-tubercular activity, with greatly attenuated hERG blockade. Two examples of this series are in preclinical development.

Antibacterial activity of silver nanoparticles against field and reference strains of Mycobacterium tuberculosis, Mycobacterium bovis and multiple-drug-resistant tuberculosis strains.

Tuberculosis (TB) is an endemic disease in animals and humans in Egypt. This study aims to investigate the antimycobacterial activity of silver nanoparticles(AgNPs) by determining the minimal inhibitory concentration (MIC) of AgNPs, using the microplate Alamar blue assay. The AgNPs were chemically synthesised and their form and size were characterised by ultraviolet-visible absorption spectrophotometry, transmission electron microscopy and X-ray diffraction.The reference strains of Mycobacterium bovis and Mycobacterium tuberculosisH37Rv, and one multiple-drug-resistant (MDR) strain of M. tuberculosis were tested, as well as clinical isolates of M. bovis and M. tuberculosis. The AgNPs were tetrahydral with a few spherical particles and an average particle size of 50 nm. The mycobacterial strains were varied with MICs of AgNPs. Both reference strains of M. tuberculosis and M. bovis, in addition to the MDR strain of M. tuberculosis, were successfully inhibited by AgNPs at MICs of 1 ?g/ml, 4 ?g/ml and 16 ?g/ml, respectively, whereas clinical isolates of M. bovis and M. tuberculosis were inhibited at MIC values of 4-32 ?g/ml and 1-16 ?g/ml, respectively. The AgNPs showed an in vitro chemotherapeutic effect against Mycobacterium spp.Thus, they can be used to treat TB not only in humans but also in animals, and maybe useful in TB prevention and control strategies worldwide.

En Egypte, la tuberculose est une maladie endémique chez l'homme comme chez l'animal. Les auteurs présentent les résultats d'une étude conduite pour mesurer l'activité antibactérienne des nanoparticules d'argent (NPAg) en déterminant les valeurs de concentration minimale inhibitrice (CMI) des NPAg au moyen du test au bleu Alamar sur microplaques. Les NPAg ont été synthétisées par une méthode chimique et leur forme et taille ont été caractérisées par spectrophotométrie d'absorption dans l'ultra-violet, microscopie électronique à transmission et diffraction des rayons X. L'étude a cible les souches de référence de Mycobacterium bovis et de Mycobacterium tuberculosis H37Rv, ainsi qu'une souche multirésistante de M. tuberculosis et des isolats cliniques de M. bovis et M. tuberculosis. Les NPAg étaient à structure tétraédrique avec quelques particules sphériques ; la taille moyenne des particules etait de 50 nm.La CMI des NPAg variait en fonction des souches. L'inhibition des deux souches de reference de M. tuberculosis et M. bovis et de la souche multirésistante de M. tuberculosis était obtenue avec des CMI de NPAg de 1 ?g/ml, 4 ?g/ml et16 ?g/ml, respectivement, tandis que les isolats cliniques de M. bovis et de M. tuberculosis étaient inhibés en présence de NPAg à des CMI comprises entre 4 et 32 ?g/ml et 1­16 ?g/ml, respectivement. L'efficacité chimiothérapeutique des NPAg contre Mycobacterium spp. a été démontrée in vitro. Ces nanoparticules peuvent donc servir à traiter la tuberculose non seulement chez l'homme mais également chez les animaux et contribuer ainsi aux stratégies de prévention et de lutte contre la tuberculose dans le monde.

En Egipto, la tuberculosis es una enfermedad endemica que afecta a personas y animales. Los autores describen un estudio encaminado a analizar la actividad antimicobacteriana de las nanoparticulas de plata, determinando para ello la concentracion inhibitoria minima de nanoparticulas mediante el ensayo de microtitulacion en placa con azul Alamar. Tras sintetizar quimicamente las nanoparticulas de plata y caracterizar su forma y tamano por espectrometria de absorcion ultravioleta-visible, microscopia electronica de transmision y difraccion de rayos X, se sometieron a prueba las cepas de referencia de Mycobacterium bovis y Mycobacterium tuberculosis H37Rv, asi como una cepa multirresistente de M. tuberculosis y muestras de M. bovis y M. tuberculosis aisladas a partir de casos clinicos. Salvo unas pocas de forma esferica, las nanoparticulas de plataeran tetraedricas. Su tamano era en promedio de 50 nm. Tras someter las cepas de micobacterias a distintas concentraciones de nanoparticulas, se observo que estas inhibian el crecimiento de las cepas de referencia de M. tuberculosis y M. bovis y de la cepa multirresistente de M. tuberculosis a concentraciones minimas de 1 ?g/ml, 4 ?g/ml y 16 ?g/ml, respectivamente, mientras que las muestras clinicas de M. bovis y M. tuberculosis quedaban inhibidas por la presencia de nanoparticulas a valores de concentracion minima de 4­32 ?g/ml y 1­16 ?g/ml, respectivamente. Tambien se observo que, in vitro, las nanoparticulas de plata mostraban actividad farmacologica contra Mycobacterium spp. De ahi se sigue que pueden ser empleadas para tratar la tuberculosis no solo en personas, sino tambien en animales, y que pueden resultar utiles en todo el mundo para las estrategias de prevencion y control de la tuberculosis.

Discovery of new leads against Mycobacterium tuberculosis using scaffold hopping and shape based similarity.

BM212 [1,5-diaryl-2-methyl-3-(4-methylpiperazin-1-yl)-methyl-pyrrole] is a pyrrole derivative with strong inhibitory activity against drug resistant Mycobacterium tuberculosis and mycobacteria residing in macrophages. However, it was not pursued because of its poor pharmacokinetics and toxicity profile. Our goal was to design and synthesize new antimycobacterial BM212 analogs with lower toxicity and better pharmacokinetic profile. Using the scaffold hopping approach, three structurally diverse heterocycles - 2,3-disubstituted imidazopyridines, 2,3-disubstituted benzimidazoles and 1,2,4-trisubstituted imidazoles emerged as promising antitubercular agents. All compounds were synthesized through easy and convenient methods and their structures confirmed by IR, 1H NMR, 13C NMR and MS. In-vitro cytotoxicity studies on normal kidney monkey cell lines and HepG2 cell lines, as well as metabolic stability studies on rat liver microsomes for some of the most active compounds, established that these compounds have negligible cytotoxicity and are metabolically stable. Interestingly the benzimidazole compound (4a) is as potent as the parent molecule BM212 (MIC 2.3µg/ml vs 0.7-1.5µg/ml), but is devoid of the toxicity against HepG2 cell lines (IC50 203.10µM vs 7.8µM).

Lauric acid and myristic acid from Allium sativum inhibit the growth of Mycobacterium tuberculosis H37Ra: in silico analysis reveals possible binding to protein kinase B.

CONTEXT: The bulb of Allium sativum Linn (Alliaceae) has numerous medicinal values. Though the petroleum ether extract of the bulb has shown to exhibit antimycobacterial activity, the phytochemical(s) responsible for this inhibitory activity is not known. OBJECTIVE: To characterize the bioactive compounds in the petroleum ether extract of Allium sativum (garlic) that inhibit the growth of Mycobacterium tuberculosis H37Ra. MATERIALS AND METHODS: Bioactivity-guided fractionation was employed to isolate the bioactive compounds. Antimycobacterial activity was evaluated by well-diffusion method and microplate alamar blue assay (MABA). Infrared spectroscopy, mass spectrometry and nuclear magnetic resonance spectroscopy were used to characterize the bioactive compounds. Autodock was used to obtain information on molecular recognition, and molecular dynamics simulation was performed using GROMACS. RESULTS: The bioactive compounds that inhibited the growth of M. tuberculosis H37Ra were found to be lauric acid (LA) and myristic acid (MA). The minimal inhibitory concentration of LA and MA was found to be 22.2 and 66.7 µg/mL, respectively. In silico analysis revealed that these fatty acids could bind at the cleft between the N-terminal and C-terminal lobes of the cytosolic domain of serine/threonine protein kinase B (PknB). DISCUSSION AND CONCLUSION: The inhibition activity was dependent on the alkyl chain length of the fatty acid, and the amino acid residues involved in binding to fatty acid was found to be conserved across the Pkn family of proteins. The study indicates the possibility of using fatty acid derivatives, involving Pkn family of proteins, to inhibit the signal transduction processes in M. tuberculosis.

Tetrazole-based deoxyamodiaquines: synthesis, ADME/PK profiling and pharmacological evaluation as potential antimalarial agents.

A series of new deoxyamodiaquine-based compounds was synthesized via the modified TMSN3-Ugi multi-component reaction and evaluated in vitro for antiplasmodial activity. The most potent compounds, 6b, 6c and 6j, showed IC50 values in the range of 6-77nM against chloroquine-resistant K1- and W2-strains of Plasmodium falciparum. In vitro ADME characterization of frontrunner compounds 6b and 6c indicates that these two compounds are rapidly metabolized and have a high clearance rate in human and rat liver microsomes. This result correlated well with an in vivo pharmacokinetics study, which showed low bioavailability of 6c in rats. Tentative metabolite identification was determined by LC-MS and suggested metabolic lability of groups attached to the tertiary nitrogen. Preliminary studies on 6b and 6c suggested strong inhibitory activity against the major CYP450 enzymes. In silico docking studies were used to rationalize strong inhibition of CYP3A4 by 6c. Full characterization and biological evaluation of the metabolites is currently underway in our laboratories.

GC-MS profiling of Vitex pinnata bark lipophilic extract and screening of its anti-TB and cytotoxic activities.

Tuberculosis is a highly infectious ailment worldwide. The emergence of multi-drug resistance and serious adverse effects of anti-TB drugs have led to the continuous search of natural candidates. This study aimed to analyse the chemical profile of Vitex pinnata (VP) bark lipophilic extract using GC-MS also evaluating its anti-TB and cytotoxic activities. GC-MS revealed a total of 81 compounds which representing 86% identified compounds. In vitro anti-TB of VP lipophilic extract was evaluated using the Microplate Alamar Blue Assay which exhibited MIC value of 62.5 µg/mL. In vitro cytotoxicity was evaluated using Water Soluble formazan assay recording IC50 > 100 and 200 µg/mL using Vero and A-549 cell lines, respectively. In silico docking study was performed on the major identified compounds, n-nonane showed the most favourable binding affinity (ΔG) equals to -33.34 Kcal/mol. The results obtained herein unravelled the potential use of VP n-hexane extract as a natural anti-TB.

Design, synthesis and biological evaluation of novel 1,2,3-triazole analogues of Imidazo-[1,2-a]-pyridine-3-carboxamide against Mycobacterium tuberculosis.

Twenty-eight novel 1,2,3-triazole analogues of imidazo-[1,2-a]-pyridine-3-carboxamide were designed and synthesized based on hybridization approach. The structure of the final compounds are characterized using 1HNMR, 13CNMR, LCMS and elemental analyses and are screened in vitro for anti-tubercular activity using low-oxygen recovery assay (LORA) non-replicating and using microplate alamar blue assay (MABA) against replicating M. tuberculosis. MIC was determined. From the obtained results, it was observed that, among (2,7-dimethylimidazo[1,2-a]pyridin-3-yl)(4-((1-subtituted phenyl-1H-1,2,3-triazol-4-yl)methyl)piperazin-1-yl)methanones and (6-chloro-2-methylimidazo[1,2-a]pyridin-3-yl)(4-((1-substituted phenyl-1H-1,2,3-triazol-4-yl)methyl)piperazin-1-yl)methanones, compounds with substitution at para position with electron electron releasing groups exhibited the best activity (< 34 µg/mL). Amidst, (2,7-dimethylimidazo[1,2-a]pyridin-3-yl)(4-(2-(4-alkyl/substituted aryl-1H-1,2,3-triazol-1-yl)ethyl)piperazin-1-yl)methanones and (6-chloro-2-methylimidazo[1,2-a]pyridin-3-yl)(4-(2-(4- alkyl/substituted aryl -1H-1,2,3-triazol-1-yl)ethyl)piperazin-1-yl)methanones, compounds with long alkyl chain or cyclo propyl group were most active (< 21 µg/mL) in MABA method against the tested strain of MTB. Compound 10b emerged to be the most active compound in MABA and LORA with MIC values 13.74 and 24.63 µg/mL respectively. In-silico ADMET parameters were also predicted for the significantly active compound. Finally, molecular docking study was carried out to predict the feasible binding pattern of the most active compound at the active site of enoyl acyl carrier protein reductase from Mycobacterium tuberculosis (PDB-4TZK) using Glide module of Schrodinger software.

Design, Synthesis and In Vitro Biological Evaluation of Pyridine, Thiadazole, Benzimidazole and Acetyl Thiophene Analogues as Anti Tubercular Agents Targeting Enzyme Inh A.

BACKGROUND: Tuberculosis is a chronic infectious disease that affects one-third of the global population. The emergence of Multi-resistant (MDR) strains and high susceptibility of human immunodeficiency virus (HIV) infected persons to the disease forced to develop novel antituberculosis agents and preferably have a novel mechanism of action as to avoid cross-resistant with other agents. A literature survey indicated that Pyridine, Thiadiazole, Benzimidazole and Acetyl thiophene derivatives exhibit various pharmacological activities, including anti-mycobacterial activity. METHODS: Thus, a series of Pyridine, Thiadiazole, Benzimidazole and Acetyl thiophene based molecules were designed and docked against crucial mtb enzyme target InhA (Enoyl Acyl Carrier Protein Reductase) Enzyme. The docked molecules were screened against good docking-score and multiple interactions and opted for synthesis. Synthesized molecules were recrystallized to obtain purity. All the purified compounds were characterized by various spectral analyses and evaluated for antimycobacterial activity against tuberculosis H37RV strain by Microplate Alamar Blue Assay (MABA) method. RESULTS: The experimental results showed that Schiff bases of Pyridine (Compounds 'd') and Benzimidazole derivatives (Compounds 'i' ) possess good anti-tubercular activity with an MIC below 1.6 µg /mL. Furthermore, compound 'e' of benzimdazole derivative showed good antitubercular activity with an MIC below 6.25 µg /mL, whereas 2 - acetyl thiopene compounds exhibited moderate antitubercular activity below 50µg/mL. CONCLUSION: The comparative in vitro and molecular docking study analysis reveals that compared to chalcones of Acetyl thiophene derivatives, Pyridine, Thiadazole and Benzimidazole based Schiff bases exhibited best antitubercular activity.

Design, synthesis and investigation on the structure-activity relationships of N-substituted 2-aminothiazole derivatives as antitubercular agents.

Tuberculosis (TB) is one of the deadliest infectious diseases of all times, and its recent resurgence is a supreme matter of concern. Co-infection with HIV and, in particular, the continuous isolation of new resistant strains, makes the discovery of novel anti-TB agents a strategic priority. The research of novel agents should be driven by the accessibility of the synthetic procedure and, in particular, by the lack of cross-resistance with the drugs already marketed. Moreover, in order to shorten the duration of the therapy, and therefore decrease the rate of resistance, these molecules should be active also against the nonreplicating persistent form (NRP-TB) of the infection. The availability of an in-house small library of compounds prompted us to investigate their anti-TB activity. Two compounds, embodying a 2-aminothiazole scaffold, were found to possess a certain inhibitory activity toward Mycobacterium tuberculosis H37Rv, and therefore a medicinal chemistry campaign was initiated in order to increase the activity of the hit compounds and, especially, construct a plausible body of structure-activity relationships. The potency of the hit compound was successfully improved, and, much more importantly, some of the molecules synthesized were found to be active toward the persistent phenotype, and, also, toward a panel of resistant strains. These findings encourage further investigations around this interesting antitubercular chemotype.