An updated review on 1,2,3-/1,2,4-triazoles: synthesis and diverse range of biological potential

The synthesis of triazoles has attracted a lot of interest in the field of organic chemistry because of its versatile chemical characteristics and possible biological uses. This review offers an extensive overview of the different pathways used in the production of triazoles. A detailed analysis of recent research indicates that triazole compounds have a potential range of pharmacological activities, including the ability to inhibit enzymes, and have antibacterial, anticancer, and antifungal activities. The integration of computational and experimental methods provides a thorough understanding of the structure-activity connection, promoting sensible drug design and optimization. By including triazoles as essential components in drug discovery, researchers can further explore and innovate in the synthesis, biological assessment, and computational studies of triazoles as drugs, exploring the potential therapeutic significance of triazoles.

Discovery of 1,2,3-triazole incorporated indole-piperazines as potent antitubercular agents: Design, synthesis, in vitro biological evaluation, molecular docking and ADME studies

In this report, a library consisting of three sets of indole-piperazine derivatives was designed through the molecular hybridization approach. In total, fifty new hybrid compounds (T1-T50) were synthesized and screened for antitubercular activity against Mycobacterium tuberculosis H37Rv strain (ATCC-27294). Five (T36, T43, T44, T48 and T49) among fifty compounds exhibited significant inhibitory potency with the MIC of 1.6 µg/mL, which is twofold more potent than the standard first-line TB drug Pyrazinamide and equipotent with Isoniazid. N-1,2,3-triazolyl indole-piperazine derivatives displayed improved inhibition activity as compared to the simple and N-benzyl indole-piperazine derivatives. In addition, the observed activity profile of indole-piperazines was similar to standard anti-TB drugs (isoniazid and pyrazinamide) against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa strains, demonstrating the compounds' selectivity towards the Mycobacterium tuberculosis H37Rv strain. All the active anti-TB compounds are proved to be non-toxic (with IC50 > 300 μg/mL) as verified through the toxicity evaluation against VERO cell lines. Additionally, molecular docking studies against two target enzymes (Inh A and CYP121) were performed to validate the activity profile of indole-piperazine derivatives. Further, in silico-ADME prediction and pharmacokinetic parameters indicated that these compounds have good oral bioavailability.

Design, synthesis and antitubercular assessment of 1, 2, 3-triazole incorporated thiazolylcarboxylate derivatives

A library of 1, 2, 3-triazole incorporated thiazolylcarboxylate derivatives (7a-q) and (8a-j) were synthesized and evaluated for their in-vitro antitubercular activity against Mycobacterium tuberculosis H37Rv. The two compounds 7h and 8h have displayed excellent antitubercular activity with MIC values of 3.12 and 1.56 µg/mL respectively (MIC values of standard drugs; Ciprofloxacin 1.56 μg/mL & Ethambutol 3.12 μg/mL). Whereas, the four compounds 7i, 7n, 7p and 8i displayed noticeable antitubercular activity with a MIC value of 6.25 µg/mL. The active compounds of the series were further studied for their cytotoxicity against RAW264.7 cell line using MTT assay. Furthermore, to study the probable mechanism of antitubercular action, physicochemical property profiling, DFT calculation and molecular docking study were executed on mycobacterial cell wall target Decaprenylphosphoryl-β-d-ribose 2'-epimerase 1 (DprE1). Among all the compounds, 7h (-10 kcal/mol) and 8h (-10.1 kcal/mol) exerted the highest negative binding affinity against the targeted DprE1 (PDB: 4NCR) protein.

Design and synthesis of imidazo[1,2-a]pyridine-chalcone conjugates as antikinetoplastid agents

A library of imidazo[1,2-a]pyridine-appended chalcones were synthesized and characterized using 1 H NMR, 13 C NMR and HRMS. The synthesized analogues were screened for their antikinetoplastid activity against Trypanosoma cruzi, Trypanosoma brucei brucei, Trypanosoma brucei rhodesiense and Leishmania infantum. The analogues were also tested for their cytotoxicity activity against human lung fibroblasts and primary mouse macrophages. Among all screened derivatives, 7f was found to be the most active against T. cruzi and T. b. brucei exhibiting IC50 values of 8.5 and 1.35 μM, respectively. Against T. b. rhodesiense, 7e was found to be the most active with an IC50 value of 1.13 μM. All synthesized active analogues were found to be non-cytotoxic against MRC-5 and PMM with selectivity indices of up to more than 50.

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.

Synthesis and pharmacological evaluation of 1,3-diaryl substituted pyrazole based (thio)urea derivatives as potent antimicrobial agents against multi-drug resistant Staphylococcus aureus and Mycobacterium tuberculosis

The urgent development of newer alternatives has been deemed a panacea for tackling emerging antimicrobial resistance effectively. Herein, we report the design, synthesis, and biological evaluation of 1,3-diaryl substituted pyrazole-based urea and thiourea derivatives as antimicrobial agents. Preliminary screening results revealed that compound 7a (3,4-dichlorophenyl derivative) exhibited potent activity against S. aureus (MIC = 0.25 μg mL-1) and compound 7j (2,4-difluorophenyl derivative) against Mycobacterium tuberculosis (MIC = 1 μg mL-1). Compounds 7a and 7j were non-toxic to Vero cells with a favorable selectivity index of 40 and 200, respectively, and demonstrated good microsomal stability. Compound 7a exhibited equipotent activity (MIC = 0.25 μg mL-1) against various multidrug-resistant strains of S. aureus, which include various strains of MRSA and VRSA, and elicited bacteriostatic properties. In an enzymatic assay, 7a effectively inhibited DNA gyrase supercoiling activity at a concentration of 8 times MIC. Further, molecular modeling studies suggested that compound 7a binds at the active site of DNA gyrase with good affinity.

Emerging impact of triazoles as anti-tubercular agent

Tuberculosis, a disease of poverty is a communicable infection with a reasonably high mortality rate worldwide. 10 Million new cases of TB were reported with approx 1.4 million deaths in the year 2019. Due to the growing number of drug-sensitive and drug-resistant tuberculosis cases, there is a vital need to develop new and effective candidates useful to combat this deadly disease. Despite tremendous efforts to identify a mechanism-based novel antitubercular agent, only a few have entered into clinical trials in the last six decades. In recent years, triazoles have been well explored as the most valuable scaffolds in drug discovery and development. Triazole framework possesses favorable properties like hydrogen bonding, moderate dipole moment, enhanced water solubility, and also the ability to bind effectively with biomolecular targets of M. tuberculosis and therefore this scaffold displayed excellent potency against TB. This review is an endeavor to summarize an up-to-date innovation of triazole-appended hybrids during the last 10 years having potential in vitro and in vivo antitubercular activity with structure activity relationship analysis. This review may help medicinal chemists to explore the triazole scaffolds for the rational design of potent drug candidates having better efficacy, improved selectivity and minimal toxicity so that these hybrid NCEs can effectively be explored as potential lead to fight against M. tuberculosis.

Pyrazole and Triazole Derivatives as Mycobacterium tuberculosis UDP-Galactopyranose Inhibitors

UDP-galactopyranose mutase (UGM) is an essential enzyme involved in the bacterial cell wall synthesis, and is not present in mammalian cells. Thus, UGM from Mycobacterium tuberculosis (Mtb) represents a novel and attractive drug target for developing antituberculosis agents. A pyrazole-based compound, MS208, was previously identified as a mixed inhibitor of MtbUGM which targets an allosteric site. To understand more about the structure activity relationship around the MS208 scaffold as a MtbUGM inhibitor, thirteen pyrazoles and triazole analogues were synthesized and tested against both MtbUGM and Mycobacterium tuberculosis in vitro. While the introduced structural modifications to MS208 did not improve the antituberculosis activity, most of the compounds showed MtbUGM inhibitory activity. Interestingly, the pyrazole derivative DA10 showed a competitive model for MtbUGM inhibition with improved Ki value of 51 ± 4 µM. However, the same compound did not inhibit the growth of Mycobacterium tuberculosis.

Pyrido[2',1':2,3]imidazo[4,5-c]isoquinolin-5-amines as Potential Cytotoxic Agents against Human Neuroblastoma

We report herein the evaluation of various pyrido[2',1':2,3]imidazo[4,5-c]isoquinolin-5-amines as potential cytotoxic agents. These molecules were obtained by developing the multicomponent Groebke-Blackburn-Bienaymé reaction to yield various pyrido[2',1':2,3]imidazo[4,5-c]quinolines which are isosteres of ellipticine whose biological activities are well established. To evaluate the anticancer potential of these pyrido[2',1':2,3]imidazo[4,5-c]isoquinolin-5-amine derivatives in the human neuroblastoma cell line, the cytotoxicity was examined using the WST-1 assay after 72 h drug exposure. A clonogenic assay was used to assess the ability of treated cells to proliferate and form colonies. Protein expressions (Bax, bcl-2, cleaved caspase-3, cleaved PARP-1) were analyzed using Western blotting. The colony number decrease in cells was 50.54%, 37.88% and 27.12% following exposure to compounds 2d, 2g and 4b respectively at 10 μM. We also show that treating the neuroblastoma cell line with these compounds resulted in a significant alteration in caspase-3 and PARP-1 cleavage.

Triazole-containing hybrids with anti-Mycobacterium tuberculosis potential - Part I: 1,2,3-Triazole

Tuberculosis regimens currently applied in clinical practice require months of multidrug therapy, which imposes a major challenge of patient compliance and drug resistance development. Moreover, because of the increasing emergence of hard-to-treat tuberculosis, this disease continues to be a significant threat to the human population. 1,2,3-triazole as a privileged structure has been widely used as an effective template for drug discovery, and 1,2,3-triazole-containing hybrids that can simultaneously act on dual or multiple targets in Mycobacterium tuberculosis have the potential to circumvent drug resistance, enhance efficacy, reduce side effects and improve pharmacokinetic as well as pharmacodynamic profiles. Thus, 1,2,3-triazole-containing hybrids are useful scaffolds for the development of antitubercular agents. This review aims to highlight recent advances of 1,2,3-triazole-containing hybrids with potential activity against various forms of M. tuberculosis, covering articles published between 2015 and 2020. The structure-activity relationship and the mechanism of action are also discussed to facilitate further rational design of more effective drug candidates.

Synthesis and antibiofilm activity of 1,2,3-triazole-pyridine hybrids against methicillin-resistant Staphylococcus aureus (MRSA)

Antibiotic-resistant bacteria are emerging at an alarming rate, posing a potential threat to human health. A series of 1,2,3-triazole-pyridine hybrids were synthesised as promising antibiofilm agents against planktonic and sessile MRSA.

SAR Analysis of Small Molecules Interfering with Energy-Metabolism in Mycobacterium tuberculosis

Tuberculosis remains the world's top infectious killer: it caused a total of 1.5 million deaths and 10 million people fell ill with TB in 2018. Thanks to TB diagnosis and treatment, mortality has been falling in recent years, with an estimated 58 million saved lives between 2000 and 2018. However, the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mtb strains is a major concern that might reverse this progress. Therefore, the development of new drugs acting upon novel mechanisms of action is a high priority in the global health agenda. With the approval of bedaquiline, which targets mycobacterial energy production, and delamanid, which targets cell wall synthesis and energy production, the energy-metabolism in Mtb has received much attention in the last decade as a potential target to investigate and develop new antimycobacterial drugs. In this review, we describe potent anti-mycobacterial agents targeting the energy-metabolism at different steps with a special focus on structure-activity relationship (SAR) studies of the most advanced compound classes.