Novel 1,2,3-Triazole Derivatives for Use against Mycobacterium tuberculosis H37Rv (ATCC 27294) Strain

Synthesis, in vitro evaluation and molecular docking studies of novel triazine-triazole derivatives as potential α-glucosidase inhibitors

A novel series of triazine-triazole derivatives 7a-7m were synthesized, characterized by ¹H NMR and evaluated for their α-glucosidase inhibitory activity. All the synthesized compounds displayed potent α-glucosidase inhibitory activity with IC₅₀ range of 11.63 ± 0.15 to 37.44 ± 0.35 μM, when compared to the standard drug acarbose (IC₅₀ = 817.38 ± 6.27 μM). Among the series, compound 7i (IC₅₀ = 11.63 ± 0.15 μM) bearing 2,5-dichloro substitution at phenyl ring, represented the most potent α-glucosidase inhibitory activity. Molecular docking studies of the most active compounds with the homology modelled α-glucosidase were also performed to explore the possible inhibitory mechanism. Our studies shown that these triazine-triazole derivatives are a new class of α-glucosidase inhibitors.

Design, synthesis, and characterization of (1-(4-aryl)- 1H-1,2,3-triazol-4-yl)methyl, substituted phenyl-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylates against Mycobacterium tuberculosis

The novel (1-(4-aryl)-1H-1,2,3-triazol-4-yl)methyl, substituted phenyl-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate derivatives were synthesized by the click reaction of the dihydropyrimidinones, bearing a terminal alkynyl group, with various substituted aryl azides at room temperature using a catalytic amount of Cu(OAc)₂ and sodium ascorbate in a 1:2 ratio of acetone and water as a solvent. The newly synthesized compounds were characterized by a number of spectroscopic techniques, such as infrared, liquid chromatography-mass spectrometry, ¹H, and ¹³C nuclear magnetic resonance along with single crystal X-ray diffraction. The current procedure for the synthesis of 1,2,3-triazole hybrids with dihydropyrimidinones is appropriate for the synthesis of a library of analogs 7a-l and the method accessible here is operationally simple and has excellent yields. The title compounds 7a-l were evaluated for their in vitro antitubercular activity against H37R_V and multidrug-resistant strains of Mycobacterium tuberculosis by resazurin microplate assay plate method and it was found that compound 7d was promising against H37R_V and multidrug-resistant strains of M. tuberculosis at 10 and 15 μg/mL, respectively.

Synthesis of Novel Symmetrical 1,4-Disubstituted 1,2,3-Bistriazole Derivatives via 'Click Chemistry' and Their Biological Evaluation

A series of symmetric bis-1,2,3-triazole compounds 2-5(a-f) were synthesized as potential antioxidant agents via click chemistry. Their structures were confirmed by ¹H-NMR and (13)C-NMR. All of the synthesized compounds were subjected to antioxidant and antimicrobial assays. The antioxidant activity of these compounds (AChE inhibition, DPPH and SOD activities) was evaluated. Compound 2f was found to show the highest AChE inhibition activity of all compounds, while compound 3b showed a strong inhibitory effect on DPPH radical and compound 2a was the most effective of all compounds for SOD activity. All synthesized compounds were found to possess moderate antibacterial activity against the bacteria E. coli and Y.pseudotuberculosis.

A Practical Approach for the Synthesis of Novel Triazolo-fused Benzazepine Derivatives Using a Multi-component Reaction and an Intramolecular C–H Arylation

An efficient and straightforward method has been developed for the preparation of triazolo-fused benzazepines by a facile, one-pot Ugi multi-component reaction/click reaction. In this strategy, the Ugi-reaction products were coupled by a click reaction, thus integrating the triazole fragment into the benzazepine structure using an intramolecular C–H arylation. The corresponding products were obtained in good yields without unfavourable by-products.

Synthesis and evaluation of novel imidazo[4,5-c]pyridine derivatives as antimycobacterial agents against Mycobacterium tuberculosis

Novel imidazo[4,5-c]pyridine derivatives showed cytotoxicity and decreased the bacterial load in lung and spleen tissues in the in vivo animal model.

Synthesis and bioactivity of novel triazole incorporated benzothiazinone derivatives as antitubercular and antioxidant agent

In search of new active molecules against Mycobacterium tuberculosis (MTB) H37Ra and M. bovis BCG, a small focused library of benzothiazinone based 1,2,3-triazoles has been efficiently prepared via click chemistry approach. Several derivatives were found to be promising inhibitors of MTB and M. bovis BCG characterized by lower MIC values (27.34-29.37μg/mL). Among all the synthesized compounds, 6c and 6e is the most active compound against MTB and M. bovis BCG. The compounds were further tested for anti-proliferative activity against HeLa, A549 and A431 cell lines using MTT assay and showed no significant cytotoxic activity at the maximum concentration evaluated. Further, the synthesized compounds were found to have potential antioxidant activity with IC50 range=14.14-47.11μg/mL. Furthermore, to rationalize the observed biological activity data, the molecular docking study also been carried out against a potential target MTB DprE1, which revealed a significant correlation between the binding score and biological activity for these compounds. The results of the in vitro and in silico study suggest that the triazole incorporated benzothiazinone may possess the ideal structural requirements for further development of novel therapeutic agents.

Overcoming drug resistance for tuberculosis

Despite enormous progress, tuberculosis (TB) is still a major global health problem. Poor patients’ adherence to the current treatment leads to the emergence of multidrug resistant (MDR) and extensively drug resistant (XDR) strains. While increased numbers of MDR-TB cases can be ascribed to difficulties in treating TB–HIV coinfected patients, many studies demonstrated that the emergence of drug-resistant TB is clearly linked to misdiagnosis and mismanagement of drug-susceptible TB. Therefore, rapid detection and proper treatment are needed globally to both cure TB patients and prevent wide spreading of the disease. This paper provides a survey of the major strategies that have been explored for overcoming drug resistance in TB.

Design, synthesis and evaluation of diarylpiperazine derivatives as potent anti-tubercular agents

Molecular hybridization is an emerging approach to design novel ligands by combination of two or more pharmacophoric subunits of known bioactive compounds. In the present study, we have designed a novel series of diarylpiperazine analogues, synthesized, characterized using FTIR, (1)H NMR, Mass, Elemental analysis and evaluated their in-vitro anti-tubercular activity. Among the reported sixteen diarylpiperazines, eleven analogues exhibited significant anti-tubercular activity against Mycobacterium tuberculosis H37Rv strain with MIC values below 6.25 μg/mL and good selectivity index. Structure activity relationship studies concluded that, ortho-para directing group (except para chloro) substitution on ortho and para position of piperazine attached phenyl ring favored anti-tubercular activity.

A click chemistry approach for the synthesis of mono and bis aryloxy linked coumarinyl triazoles as anti-tubercular agents

A series of mono and bis-triazole coumarin hybrids 6a-u and 9a-f respectively have been synthesized using 4-(azidomethyl)-2H-chromen-2-ones 5a-i and aryl propargyl ethers 2a-c/8 employing Click chemistry modified protocol for Azide-Alkyne cycloadditions(CuAAC). Anti-tubercular screening showed moderate activity for mono aryloxy compounds 6a-u with MIC 50-100 μg/mL, whereas the bis compounds 9a-f were more effective with MICs between 0.2 and 12.5 μg/mL. Molecular modeling and 3D-QSAR measurements using CoMFA and Topomer CoMFA further supported the observed results. The bis compound 9b showed excellent activity with MIC value as low as 0.2 μg/mL.

Design and synthesis of 11α-substituted bile acid derivatives as potential anti-tuberculosis agents

We have synthesized a series of novel 11α-triazoyl bile acid derivatives. In addition, we also have synthesized N-alkyl and N-acyl derivatives of C-11 amino bile acid esters. All the compounds were evaluated for the inhibitory activity against Mycobacterium tuberculosis H37Ra (MTB) at 30 μg/mL level. Four lead compounds (2b, 3, 7 and 8) were further confirmed from their dose dependent effect against MTB. These compounds were found to be active against Dormant and active stage MTB under both in vitro as well as within THP1 host macrophages. The most promising compound 2b showed strong antitubercular activities against MTB under in vitro and ex vivo (IC90 value of ∼3 μg/mL) conditions and almost insignificant cytotoxicity up to 100 μg/mL against THP-1, A549 and PANC-1 human cancer cell lines. Inactivity of all these compounds against Gram positive and Gram negative bacteria indicates their specificity. Molecular docking studies of these compounds into the active site of DprE1 enzyme revealed a similar binding mode to native ligands in the crystal structure thereby helping to establish a structural basis of inhibition of MTB. The synthesized compounds were analyzed for ADME properties and showed potential to develop good oral drug candidates. Our results clearly indicate the identification of some novel, selective and specific inhibitors against MTB that can be explored further for potential antitubercular drug.

Design, synthesis and antitubercular activity of certain nicotinic Acid hydrazides

Three series of 6-aryl-2-methylnicotinohydrazides 4a–i, N′-arylidene-6-(4-bromophenyl)-2-methylnicotino hydrazides 7a–f, and N′-(un/substituted 2-oxoindolin-3-ylidene)-6-(4-fluorophenyl)-2-methylnicotinohydrazides 8a–c were synthesized and evaluated for their potential in vitro antimycobacterial activity against M. tuberculosis. The results showed that isatin hydrazides 8a–c are remarkably more active than the parent hydrazide 4c. Hydrazides 8b and 8c exhibited the highest activity among all the tested compounds (MIC = 12.5 and 6.25 µg/mL, respectively). Compounds 8b and 8c were also devoid of apparent cytotoxicity to HT-29, PC-3, A549, HepG2 and MCF-7 cancer cell lines. Besides, 8b and 8c showed good drug-likeness scores of 0.62 and 0.41, respectively. Those two isatin hydrazides could offer an excellent framework for future development to obtain more potent antitubercular agents. The SAR study suggested that lipophilicity of the synthesized derivatives is a crucial element that accounts for their antimycobacterial activity. Finally, a theoretical kinetic study was established to predict the ADME of the active derivatives.

Novel 1,4-substituted-1,2,3-triazoles as antitubercular agents

Tuberculosis (TB) remains a pressing unmet medical need, particularly with the emergence of multidrug-resistant and extensively drug-resistant tuberculosis. Here, a series of 1,4-substituted-1,2,3-triazoles have been synthesized and evaluated as potential antitubercular agents. These compounds were assembled via click chemistry in high crude purity and in moderate to high yield. Of the compounds tested, 12 compounds showed promising antitubercular activity with six possessing minimum inhibitory concentration (MIC) values <10 μg mL(-1) , and total selectivity for Mycobacterium tuberculosis (Mtb) growth inhibition. A second set of 21 compounds bearing variations on ring C were synthesized and evaluated. This second library gave an additional six compounds displaying MIC values ≤10 μg mL(-1) and total selectivity for Mtb growth inhibition. These compounds serve as an excellent starting point for further development of antitubercular therapies.

Triazole: A Promising Antitubercular Agent

Tuberculosis is a contagious disease with comparatively high mortality worldwide. The statistics shows that around three million people throughout the world die annually from tuberculosis and there are around eight million new cases each year, of which developing countries showed major share. Therefore, the discovery and development of effective antituberculosis drugs with novel mechanism of action have become an insistent task for infectious diseases research programs. The literature reveals that, heterocyclic moieties have drawn attention of the chemists, pharmacologists, microbiologists, and other researchers owing to its indomitable biological potential as anti-infective agents. Among heterocyclic compounds, triazole (1,2,3-triazole/1,2,4-triazole) nucleus is one of the most important and well-known heterocycles, which is a common and integral feature of a variety of natural products and medicinal agents. Triazole core is considered as a privileged structure in medicinal chemistry and is widely used as 'parental' compounds to synthesize molecules with medical benefits, especially with infection-related activities. In the present review, we have collated published reports on this versatile core to provide an insight so that its complete therapeutic potential can be utilized for the treatment of tuberculosis. This review also explores triazole as a potential targeted core moiety against tuberculosis and various research ongoing worldwide. It is hoped that this review will be helpful for new thoughts in the quest for rational designs of more active and less toxic triazole-based antituberculosis drugs.

Direct access to 1,4-disubstituted 1,2,3-triazoles through organocatalytic 1,3-dipolar cycloaddition reaction of α,β-unsaturated esters with azides

DBU-catalyzed organocatalytic 1,3-dipolar cycloaddition reactions of α,β-unsaturated esters with azides have been developed. This strategy generates 1,4-disubstituted 1,2,3-triazoles in high yields with high regioselectivities.

1,2,3-Triazole derivatives as antitubercular agents: synthesis, biological evaluation and molecular docking study

A library of thirty one 1,2,3-triazole derivatives efficiently preparedviaclick chemistry and evaluated for their antitubercular, antioxidant, and cytotoxic activities.

Novel isoniazid–amidoether derivatives: synthesis, characterization and antimycobacterial activity evaluation

A series of isoniazid–amidoether derivatives was synthesized and screened for their antimycobacterial activity in vitro and in vivo.

Synthesis of new generation triazolyl- and isoxazolyl-containing 6-nitro-2,3-dihydroimidazooxazoles as anti-TB agents: in vitro, structure–activity relationship, pharmacokinetics and in vivo evaluation

Promising nitroimidazoloxazole scaffold gives another novel triazolyl-containing 6-nitro-2,3-dihydroimidazooxazole as anti-TB lead.

Two Cu(ii) complexes of triadimefon: crystal structure, antifungal activities and structure–activity relationship

Theoretical investigations of the electronic structures of Cu(ii) complexes carried out by DFT calculations partially explained the increased biocidal properties.

Synergistic actions between tebuconazole ligand and Cu(ii) cation: reasons for the enhanced antifungal activity of four Cu(ii) complexes based on the fungicide tebuconazole

The enhanced antifungal activity of four synthesized complexes is due to the synergistic actions of tebuconazole ligand and Cu(ii) cation.

Chalcomer assembly of optical chemosensors for selective Cu2+ and Ni2+ ion recognition

The o-, m- and p-isomeric units of chalconyl triazole-based, caged organosilicon complexes were efficiently synthesized and explored for their cationic chemosensing activities.

Synthesis and evaluation of thieno[2,3-d]pyrimidin-4(3H)-ones as potential antitubercular agents

Thieno[2,3-d]pyrimidin-4(3H)-ones with structures 11–38 were synthesized and some of them were found to be potent inhibitors of Mycobacterium tuberculosis H37Ra and/or Mycobacterium bovis BCG and non-toxic to human cell lines.

Synthesis and antifungal activity of 1,2,3-triazole phenylhydrazone derivatives

A series of 1,2,3-triazole phenylhydrazone derivatives were designed and synthesized as antifungal agents. Their structures were determined based on (1)H-NMR spectroscopy, MS, elemental analysis and X-ray single-crystal diffraction. The antifungal activities were evaluated against four phytopathogenic fungi including Rhizoctonia solani, Sclerotinia sclerotiorum, Fusarium graminearum and Phytophthora capsici, by the mycelium growth inhibition method in vitro. Compound 5p exhibited significant anti-phytopathogenic activity, with the EC50 values of 0.18, 2.28, 1.01, and 1.85 μg mL(-1), respectively. In vivo testing demonstrated that 5p was effective in the control of rice sheath blight, rape sclerotinia rot and fusarium head blight. A 3D-QSAR model was built for a systematic SAR profile to explore more potent 1,2,3-triazole phenylhydrazone analogs as novel fungicides.

Synthesis of novel 1,2,3-triazole derivatives of isoniazid and their in vitro and in vivo antimycobacterial activity evaluation

We report herein the synthesis and antimycobacterial activity of 1,2,3-triazole derivatives of isoniazid. Most of the compounds exhibited potent activity against Mycobacterium tuberculosis H37Rv strain with MIC99 values ranging from 0.195 to 1.56 μM in vitro. One compound showed better in vitro activity than the reference, whereas five compounds were equally potent to the reference compound isoniazid. The cytotoxicity of these compounds was studied against THP-1 cell line and no toxicity was observed even at 50 μM concentration. The compound with most potent in vitro activity was evaluated for in vivo in murine model of tuberculosis and significantly reduced bacillary load in both lungs and spleen at 10 weeks post-treatment. However this clearance effect was more pronounced in the case of spleen. Molecular docking and molecular dynamics simulations have been performed using two targets 2IDZ 1 (wild type Enoyl-acyl-carrier-protein reductase) and 4DQU 2 (mutant type Enoyl-acyl-carrier-protein reductase) to study the binding orientation and stability of the compound 47. Docking studies proved compound 47 fit well into the binding pocket of both the targets. Molecular dynamic simulations concluded that the highest active compound 47 in complex with 4DQU was more stable when compared to the 2IDZ. We believe that further optimization of these molecules may lead to potent anti-tubercular agents.

Progress in targeting cell envelope biogenesis in Mycobacterium tuberculosis

Most of the newly discovered compounds showing promise for the treatment of TB, notably multidrug-resistant TB, inhibit aspects of Mycobacterium tuberculosis cell envelope metabolism. This review reflects on the evolution of the knowledge that many of the front-line and emerging products inhibit aspects of cell envelope metabolism and in the process are bactericidal not only against actively replicating M. tuberculosis, but contrary to earlier impressions, are effective against latent forms of the disease. While mycolic acid and arabinogalactan synthesis are still primary targets of existing and new drugs, peptidoglycan synthesis, transport mechanisms and the synthesis of the decaprenyl-phosphate carrier lipid all show considerable promise as targets for new products, older drugs and new combinations. The advantages of whole cell- versus target-based screening in the perpetual search for new targets and products to counter multidrug-resistant TB are discussed.