Synthesis, antitubercular activity, and SAR study of N-substituted-phenylamino-5-methyl-1H-1,2,3-triazole-4-carbohydrazides

Exploration of triazole derivatives, SAR profiles, and clinical pipeline against Mycobacterium tuberculosis

Tuberculosis is a highly infectious disease and it is a global threat in particular affecting people from developing countries. It is thought that nearly one-third of the global population lives with this causative bacterium in its dominant form. The spread of HIV and the development of resistance to both multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) aggravates the spread of the disease and needs novel drugs which combat this disease effectively. Triazole-containing anti-tubercular drugs are promising and need further tuning to develop as a potent scaffold for tuberculosis. In this review, we highlight the structural activity relationships of triazole-containing drugs and detailed understanding for the researchers in the field of medicinal chemistry to further explore these triazole-based compounds as well as synthesize new compounds for antitubercular activity against drug-sensitive and resistant strains.

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.

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.

Chemistry and anti-herpes simplex virus type 1 evaluation of 4-substituted-1H-1,2,3-triazole-nitroxyl-linked hybrids

HSV disease is distributed worldwide. Anti-herpesvirus drugs are a problem in clinical settings, particularly in immunocompromised individuals undergoing herpes simplex virus type 1 infection. In this work, 4-substituted-1,2,3-1H-1,2,3-triazole linked nitroxyl radical derived from TEMPOL were synthesized, and their ability to inhibit the in vitro replication of HSV-1 was evaluated. The nitroxide derivatives were characterized by infrared spectroscopy and elemental analysis, and three of them had their crystal structures determined by single-crystal X-ray diffraction. Four hybrid molecules showed important anti-HSV-1 activity with IC50 values ranged from 0.80 to 1.32 µM. In particular, one of the nitroxide derivatives was more active than Acyclovir (IC50 = 0.99 µM). All compounds tested were more selective inhibitors than the reference antiviral drug. Among them, two compounds were 4.5 (IC50 0.80 µM; selectivity index CC50/IC50 3886) and 7.7 times (IC50 1.10 µM; selectivity index CC50/IC50 6698) more selective than acyclovir (IC50 0.99 µM; selectivity index CC50/IC50: 869). These nitroxide derivatives may be elected as leading compounds due to their antiherpetic activities and good selectivity.

1,2,3-Triazoles of 8-Hydroxyquinoline and HBT: Synthesis and Studies (DNA Binding, Antimicrobial, Molecular Docking, ADME, and DFT)

A new series of 1,2,3-triazole hybrids containing either 2- or 4-hydroxyphenyl benzothiazole (2- or 4-HBT) and naphthalen-1-ol or 8-hydroxyquinoline (8-HQ) was synthesized in high yields and fully characterized. In vitro DNA binding studies with herring fish sperm DNA (hs-DNA) showed that quinoline- and 2-HBT-linked 1,2,3-triazoles of shorter alkyl linkers such as 6a are better with a high binding affinity (3.90 × 105 L mol-1) with hs-DNA as compared to naphthol- and 4-HBT-linked 1,2,3-triazoles bound to longer alkyl linkers. Molecular docking of most active 1,2,3-triazoles 6a-f showed high binding energy of 6a (-8.7 kcal mol-1). Also, compound 6a displayed considerable antibacterial activity and superior antifungal activity with reference to ciprofloxacin and fluconazole, respectively. The docking results of the fungal enzyme lanosterol 14-α-demethylase showed high binding energy for 6a (-9.7 kcal mol-1) involving dominating H-bonds, electrostatic interaction, and hydrophobic interaction. The absorption, distribution, metabolism, and excretion (ADME) parameter, Molinspiration bioactivity score, and the PreADMET properties revealed that most of the synthesized 1,2,3-triazole molecules possess desirable physicochemical properties for drug-likeness and may be considered as orally active potential drugs. The electrophilicity index and chemical hardness properties were also studied by density functional theory (DFT) using the B3LYP/6-311G(d,p) level/basis set.

Bioactive 1,2,3-Triazoles: An Account on their Synthesis, Structural Diversity and Biological Applications

The triazole heterocycle is a privileged scaffold in medicinal chemistry, since its structure is present in a large number of biologically active molecules, including several drugs currently in the market. Due to their vast applications, a wide variety of methods are described for their preparation, such as the 1,3-dipolar cycloaddition and processes involving diazo compounds and diazo transfer reactions. Considering the significant number of contributions from our research group to this chemistry in recent decades, in this account we discuss both the development of new methods for the synthesis of 1,2,3-triazoles and the preparation of new triazole-functionalized biologically active molecules using classical approaches.

Ruthenocycles of benzothiazolyl and pyridyl hydrazones with ancillary PAHs: synthesis, structure, electrochemistry and antimicrobial activity

The antimicrobial activity of ruthenocycles of pyridyl and benzothiazolyl hydrazones has been investigated. The study established that such activity is comparatively higher for the complex containing benzothiazolyl hydrazone.

Exploring the Molecular Mechanisms Underlying the in vitro Anticancer Effects of Multitarget-Directed Hydrazone Ruthenium(II)-Arene Complexes

The molecular targets and the modes of action behind the cytotoxicity of two structurally established N,O- or N,N-hydrazone ruthenium(II)-arene complexes were explored in human breast adenocarcinoma cells (MCF-7) and paralleled in non-cancerous and cisplatin-resistant counterparts (MCF-10A and MCF-7CR respectively). Both complexes, [Ru(hmb)(L1)Cl] (1, L1=4-((2-(2,4-dinitrophenyl)hydrazono)(phenyl)methyl)-3-methyl-1-phenyl-1H-pyrazol-5-olate) and [Ru(cym)(L2)Cl] (2, L2=1-((3-methyl-5-oxo-1-phenyl-1H-pyrazol-4(5H)-ylidene)(phenyl)methyl)-2-(pyridin-2-yl)hydrazin-1-ide), reversibly interact with moderate-to-high affinity with a number of molecular targets in cell-free assays, namely serum albumin, DNA, the 20S proteasome and hydroxymethylglutaryl-CoA reductase. Most interestingly, only 2 readily crosses the cell membrane and preserves its binding/modulatory ability toward the targets of interest upon rapid cellular internalization. The resulting action at multiple levels of the cancer cascade is likely the cause for the selective sensitization of tumour cells to p27-mediated apoptotic death, and for the ability of 2 to overcome the drug resistance problem.

Current development of 5-nitrofuran-2-yl derivatives as antitubercular agents

Pulmonary tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (MTB) and still remains one of the foremost fatal infectious diseases, infecting nearly a third of the worldwide population. The emergencies of multidrug-resistant and extensively drug-resistant tuberculosis (MDR and XDR-TB) prompt the efforts to deliver potent and novel anti-TB drugs. Research aimed at the development of new anti-TB drugs based on nitrofuran scaffold led to the identification of several candidates that were effective against actively growing as well as latent mycobacteria with unique modes of action. This review focuses on the recent advances in nitrofurans that could provide intriguing potential leads in the area of anti-TB drug discovery.

Preparation and molecular structures of N′-(2-heteroarylmethylidene)-3-(3-pyridyl)acrylohydrazides

The crystal and molecular structures of N′-(2-furylmethylidene)-3-(3-pyridyl)acrylohydrazide and N′-(2-thienylmethylidene)-3-(3-pyridyl)acrylohydrazide are reported, and the influence of the type of the heteroatom on the aromaticity of the aromatic rings is discussed. Both molecules are nearly planar. The geometry of the acrylohydrazide arrangement is comparable to that of homologous compounds. Density functional theory (DFT) calculations were performed in order to analyze the changes in the geometry of the studied compounds in the crystalline state and for the isolated molecule. The most significant changes were observed in the values of the N–N and C–N bond lengths. The harmonic oscillator model of aromaticity index, calculated for the furan and thiophene rings, demonstrated a noticeable increase in aromaticity in comparison to isolated rings and their DFT-calculated structures. By contrast, the nucleus independent chemical shift index indicated a decrease in aromatic character of the rings containing heteroatoms.

Hetero-Diels-Alder reactions of novel 3-triazolyl-nitrosoalkenes as an approach to functionalized 1,2,3-triazoles with antibacterial profile

The generation and reactivity of 3-triazolyl-nitrosoalkenes are reported for the first time. The study showed that hetero-Diels-Alder reaction of these heterodienes is an interesting synthetic strategy to functionalized 1,2,3-triazoles, including 1,2,3-triazolyl-pyrroles, 1,2,3-triazolyl-dipyrromethanes and 1,2,3-triazolyl-indoles. The evaluation of the antibacterial profile against Gram-positive and Gram-negative strains revealed the new 5,5'-diethyldipyrromethane bearing a side chain incorporating a triazole and oxime moieties. The antibacterial profile detected was within the Clinical and Laboratory Standard Institute (CLSI) range and against important Staphylococcus species including Methicillin-resistant strain (S. aureus ATCC 25923, S. epidermidis ATCC 12228 and S. simulans ATCC 27851 and MRSA). Interestingly, this new 1,2,3-triazole presented hemocompatibility and low in silico toxicity profile similar to antibiotics current in use. It also has an usual antibiofilm activity against MRSA, which reinforced its potential as a new antibacterial prototype.

Triazole derivatives and their anti-tubercular activity

Tuberculosis (TB) remains one of the most widespread and leading deadliest diseases, threats one-third of the world's population. Although numerous efforts have been undertaken to develop new anti-TB agents, only a handful of compounds have entered human trials in the past 5 decades. Triazoles including 1,2,3-triazole and 1,2,4-triazole are one of the most important classes of nitrogen containing heterocycles that exhibited various biological activities. Triazole derivatives are regarded as a new class of effective anti-TB candidates owing to their potential anti-TB potency. Thus, molecules containing triazole moiety may show promising in vitro and in vivo anti-TB activities and might be able to prevent the drug resistant to certain extent. This review outlines the advances in the application of triazole-containing hybrids as anti-TB agents, and discusses the structure-activity relationship of these derivatives.

1-Anilino-5-methyl-1H-1,2,3-triazole-4-carbaldehyde

The title compound, C10H10N4O, is twisted about the Nring—Naminebond with the dihedral angle between the 1,2,3-triazolyl and N-bound phenyl rings being 79.14 (9)°. The C-bound aldehyde group is coplanar with the triazolyl ring, with the N—C—C—O torsion angle being 3.5 (3)°. While coplanar, the aldehyde O atom is orientated in the opposite direction to the triazolyl-bound methyl group. The most prominent feature of the molecular packing is the formation of zigzag chains (glide symmetry) along thebaxis and mediated by amine-N—H...N(triazolyl) hydrogen bonds. The chains are connected into supramolecular layers by phenyl- and methyl-C—H...O(aldehyde) interactions, with phenyl groups projecting to either side. Layers stack along thecaxis with no directional interactions between them.

[1-(2,5-Dichloroanilino)-5-methyl-1H-1,2,3-triazol-4-yl]methanol

In the title compound, C10H10Cl2N4O, the hydroxy group and benzene ring are disposed to opposite sides of the central 1,2,3-triazolyl ring. The dihedral angle between the five- and six-membered rings is 87.51 (12)°, and the C—O bond of the hydroxy group lies almost normal to the plane of the 5-membered ring [N—C—C—O = −93.2 (2)°]. An intramolecular amino-N—H...Cl hydrogen bond is noted. In the extended structure, supramolecular layers in theabplane are formedviahydroxy-O—H...N(ring) and amine-N—H...O(hydroxy) hydrogen bonds. The layers are connected along thecaxis by π–π contacts between benzene rings [inter-centroid distance = 3.7789 (13) Å] and by C—Cl...π interactions.

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.

Therapeutic potential of hydrazones as anti-inflammatory agents

Hydrazones are a special class of organic compounds in the Schiff base family. Hydrazones constitute a versatile compound of organic class having basic structure (R₁R₂C=NNR₃R₄). The active centers of hydrazone, that is, carbon and nitrogen, are mainly responsible for the physical and chemical properties of the hydrazones and, due to the reactivity toward electrophiles and nucleophiles, hydrazones are used for the synthesis of organic compound such as heterocyclic compounds with a variety of biological activities. Hydrazones and their derivatives are known to exhibit a wide range of interesting biological activities like antioxidant, anti-inflammatory, anticonvulsant, analgesic, antimicrobial, anticancer, antiprotozoal, antioxidant, antiparasitic, antiplatelet, cardioprotective, anthelmintic, antidiabetic, antitubercular, trypanocidal, anti-HIV, and so forth. The present review summarizes the efficiency of hydrazones as potent anti-inflammatory agents.

Lead optimization of an acylhydrazone scaffold possessing antiviral activity against Lassa virus

Previously we reported the optimization of antiviral scaffolds containing benzimidazole and related heterocycles possessing activity against a variety of arenaviruses. These series of compounds were discovered through an HTS campaign of a 400,000 small molecule library using lentivirus-based pseudotypes incorporated with the Lassa virus envelope glycoprotein (LASV GP). This screening also uncovered an alternate series of very potent arenavirus inhibitors based upon an acylhydrazone scaffold. Subsequent SAR analysis of this chemical series involved various substitutions throughout the chemical framework along with assessment of the preferred stereochemistry. These studies led to an optimized analog (ST-161) possessing subnanomolar activity against LASV and submicromolar activity against a number of other viruses in the Arenaviridae family.