Coumarinyl pyrazole derivatives of INH: promising antimycobacterial agents

Synthesis, antimycobacterial, cytotoxicity, anti-inflammatory, in silico studies and molecular dynamics of pyrazole-embedded thiazolidin-4-one hybrids

In the present investigation, we devolved and synthesized a new series of pyrazole-embedded thiazolidin-4-one derivatives (9a-p) with the goal to produce promising antitubercular leads. The in vitro antimycobacterial activity of the synthesized compounds was tested against replicating and nonreplicating Mtb H37Rv strains. With MIC ranging from 3.03 to 22.55 µg/ml, five compounds (9a, 9c, 9d, 9e, and 9f) emerged as promising antitubercular agents. The active molecules were nontoxic to normal Vero cells. All the synthesized compounds were evaluated for in vitro anti-inflammatory studies. Compounds 9a, 9b, 9c, 9h, and 9i exhibited excellent anti-inflammatory efficacy. Docking study was performed to understand the binding pattern of the significantly active compound 9a with 1P44.

Polysorbate 21 Can Modulate the Antibacterial Potential of Two Pyrazol Derivatives

The combination of two compounds with known antimicrobial activity may, in some cases, be an effective way to limit the resistance to antibiotics of specific pathogens. Molecules carrying pyrazole moiety are well known for their bioactive properties and have wide applicability in the medical and pharmaceutical field. Surfactants have, among other useful properties, the ability to affect the growth of microorganisms. The paper reports on the effect of the combination of two pyrazole derivatives, (1H-pyrazol-1-yl) methanol 1-hydroxymethylpyrazole (SAM1) and 1,1'methandiylbis (1H-pyrazol) (AM1), with sorbitan monolaurate (polysorbate 21, Tween 21, T21) on the growth of Gram-positive and Gram-negative bacteria. The results demonstrated a different ability of this combination to inhibit Staphylococcus aureus and Escherichia coli. T21 intensified the inhibitory activity of the pyrazoles to a greater extent in the Gram-negative bacteria compared to the Gram-positive ones, a fact confirmed by time-kill experiments. The experimental data showed that the association of T21 with the pyrazoles led to the increased release of intracellular material and a more intense uptake of crystal violet, which indicates that the potentiation of the antibacterial effect was based on the modification of the normal permeability of bacterial cells. T21 acted as a modulating factor and increased the permeability of the membrane, allowing the accelerated penetration of the pyrazoles inside the bacterial cells. This fact is important in controlling the global increase in microbial resistance to antibiotics and antimicrobials and finding viable solutions to overcome the antibiotic crisis. The paper highlights the possibility of using non-toxic surfactant molecules in antimicrobial combinations with practical applications. This could widen the range of adjuvants in applications which would be useful in the control of resistant microorganisms.

Hybridization Approach to Drug Discovery Inhibiting Mycobacterium tuberculosis-An Overview

Tuberculosis is one of the top 10 causes of death worldwide and the leading cause of death from a single infectious agent, mainly due to Mycobacterium tuberculosis (MTB). Recently, clinical prognoses have worsened due to the emergence of multi-drug resistant (MDR) and extensive-drug resistant (XDR) tuberculosis, which lead to the need for new, efficient and safe drugs. Among the several strategies, polypharmacology could be considered one of the best solutions, in particular, the multitarget directed ligands strategy (MTDLs), based on the synthesis of hybrid ligands acting against two targets of the pathogen. The framework strategy comprises linking, fusing and merging approaches to develop new chemical entities. With these premises, this review aims to provide an overview of the recent hybridization approach, in medicinal chemistry, of the most recent and promising multitargeting antimycobacterial candidates.

Contribution of N-heterocycles towards anti-tubercular drug discovery (2014-2019); predicted and reengineered molecular frameworks

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis, responsible for high death frequency every year all over the world. In this regard, efficient drug-design and discovery towards the prevention of M.tb H₃₇ R_v is of prime concern. Prevention of the infection may include vaccination, and the treatment comprises anti-TB drug regimen. However, the vaccine decreases the risk of tuberculosis infection only to some extent, while drug-resistance limits the efficacy of the existing anti-TB agents. Much improvement has to be achieved to overcome pitfalls such as side effects, high-toxicity, low bioavailability, pharmacokinetics and pharmacodynamics, and hence forth in clinical therapeutics. Amongst heterocyclic compounds, N-heterocycles played a pivotal role in drug-design and discovery. A wide range of microbial diseases are being treated by the N-heterocyclic drugs. The present review comprises description of anti-TB effects of the N-heterocycles such as indoles, triazoles, thiazoles, and pyrazoles. The potent anti-TB activity exerted by the derivatives of these heterocycles is evaluated critically alongside emphasizing structure-activity relationship. Besides, docking studies supporting anti-TB activity is supplemented. Alongside this, based on the potent heterocyclic molecules, the molecular frameworks are designed that would bring about enhanced M. tb H₃₇ R_v inhibitory potencies.

Design, synthesis, in silico, and in vitro evaluation of 3-phenylpyrazole acetamide derivatives as antimycobacterial agents

Mycobacterium tuberculosis (Mtb) is one of the most dangerous pathogens affecting immunocompetent and immunocompromised patients worldwide. Novel molecules, which are efficient and can reduce the duration of therapy against drug-resistant strains, are an urgent unmet need of the hour. In our current study, a series of new 2-(3-phenyl-1H-pyrazol-1-yl)acetamide and N'-benzylidene-2-(3-phenyl-1H-pyrazol-1-yl)acetohydrazide derivatives were designed, synthesized, and evaluated for their antimycobacterial potential. The biological evaluation revealed that 6b, 6m, 6l, 7a, and 7k exhibited selective and potent inhibitory activity against Mtb. Furthermore, compounds 6m and 7h were found to be nontoxic to Vero cells with CC₅₀ of greater than 20 and 80 mg/ml, respectively, and exhibited promising selectivity indices (SI) of greater than 666 and 320, respectively. All derivatives exhibited excellent ADME (absorption, distribution, metabolism, and excretion) properties in silico. Also, all the derivatives were found compliant with Lipinski's rule of five, showing their druggability profile. Molecular docking insights of these derivatives have shown outstanding binding energies on the mycobacterial membrane protein large transporters. These results indicate that this scaffold may lead to a potential antimycobacterial drug candidate in the discovery of antitubercular agents.

Synthesis and Pharmacological Activities of Pyrazole Derivatives: A Review

Pyrazole and its derivatives are considered a pharmacologically important active scaffold that possesses almost all types of pharmacological activities. The presence of this nucleus in pharmacological agents of diverse therapeutic categories such as celecoxib, a potent anti-inflammatory, the antipsychotic CDPPB, the anti-obesity drug rimonabant, difenamizole, an analgesic, betazole, a H2-receptor agonist and the antidepressant agent fezolamide have proved the pharmacological potential of the pyrazole moiety. Owing to this diversity in the biological field, this nucleus has attracted the attention of many researchers to study its skeleton chemically and biologically. This review highlights the different synthesis methods and the pharmacological properties of pyrazole derivatives. Studies on the synthesis and biological activity of pyrazole derivatives developed by many scientists around the globe are reported.

Synthesis and Pharmacological Activities of Pyrazole Derivatives: A Review

Pyrazole and its derivatives are considered a pharmacologically important active scaffold that possesses almost all types of pharmacological activities. The presence of this nucleus in pharmacological agents of diverse therapeutic categories such as celecoxib, a potent anti-inflammatory, the antipsychotic CDPPB, the anti-obesity drug rimonabant, difenamizole, an analgesic, betazole, a H2-receptor agonist and the antidepressant agent fezolamide have proved the pharmacological potential of the pyrazole moiety. Owing to this diversity in the biological field, this nucleus has attracted the attention of many researchers to study its skeleton chemically and biologically. This review highlights the different synthesis methods and the pharmacological properties of pyrazole derivatives. Studies on the synthesis and biological activity of pyrazole derivatives developed by many scientists around the globe are reported.

Recent advances of pyrazole-containing derivatives as anti-tubercular agents

One-third of the world's population infected tuberculosis (TB), and more than 1 million deaths annually. The co-infection between the mainly pathogen Mycobacterium tuberculosis (MTB) and HIV, and the incidence of drug-resistant TB, multi-drug resistant TB, extensively drug-resistant TB as well as totally drug-resistant TB have further aggravated the mortality and spread of this disease. Thus, there is an urgent need to develop novel anti-TB agents against both drug-susceptible and drug-resistant TB. The wide spectrum of biological activities and successful utilization of pyrazole-containing drugs in clinic have inspired more and more attention towards this kind of heterocycles. Numerous of pyrazole-containing derivatives have been synthesized for searching new anti-TB agents, and some of them showed promising potency and may have novel mechanism of action. This review aims to outline the recent achievements in pyrazole-containing derivatives as anti-TB agents and their structure-activity relationship.

Synthesis, antimycobacterial activity and docking study of 2-aroyl-[1]benzopyrano[4,3-c]pyrazol-4(1H)-one derivatives and related hydrazide-hydrazones

A new convenient method for preparation of 2-aroyl-[1]benzopyrano[4,3-c]pyrazol-4(1H)-one derivatives 5b-g and coumarin containing hydrazide-hydrazone analogues 4a-e was presented. The antimycobacterial activity against reference strain Mycobacterium tuberculosis H37Rv and cytotoxicity against the human embryonic kidney cell line HEK-293 were tested in vitro. All compounds demonstrated significant minimum inhibitory concentrations (MIC) ranging 0.28-1.69μM, which were comparable to those of isoniazid. The cytotoxicity (IC₅₀>200µM) to the "normal cell" model HEK-293T exhibited by 2-aroyl-[1]benzopyrano[4,3-c]pyrazol-4(1H)-one derivatives 5b-e, was noticeably milder compared to that of their hydrazone analogues 4a-e (IC₅₀ 33-403µM). Molecular docking studies on compounds 4a-e and 5b-g were also carried out to investigate their binding to the 2-trans-enoyl-ACP reductase (InhA) enzyme involved in M. tuberculosis cell wall biogenesis. The binding model suggested one or more hydrogen bonding and/or arene-H or arene-arene interactions between hydrazones or pyrazole-fused coumarin derivatives and InhA enzyme for all synthesized compounds.

Isoniazid derivatives and their anti-tubercular activity

Tuberculosis (TB), which has been a scourge of humanity for thousands of years, is a worldwide pandemic disease caused mainly by Mycobacterium tuberculosis (MTB). The emergence of drug-resistant TB (DR-TB), multidrug-resistant TB (MDR-TB), extensively drug-resistant TB (XDR-TB) and totally drug-resistant TB (TDR-TB) increase the challenges to eliminate TB worldwide. Isoniazid (INH), a critical frontline anti-TB drug, is one of the most effective drugs used to treatment of TB infection for more than 60 years. Unfortunately, bacterial strains resistant to INH are becoming common which mainly due to the long-term widely use even abuse. Therefore, there is an urgent need to develop novel anti-TB agents. Numerous efforts have been undertaken to develop new anti-TB agents, but no new drug has been introduced for more than 5 decades. It has been suggested that the incorporation of lipophilic moieties into the framework of INH can increase permeation of the drug into bacterial cells, thereby enhancing the anti-TB. Therefore, INH derivatives with greater lipophilicity are emerging as one of the most potential anti-TB agents. Indeed, the INH derivative LL-3858 is in initial stages of phase II clinical trial for the treatment of TB and may be approved to treat TB in the near future. This review aims to summarize the recent advances made towards the discovery anti-TB agents holding INH as a nucleus including INH hybrids and INH hydrazide-hydrazone derivatives.

Recent progress in the drug development of coumarin derivatives as potent antituberculosis agents

Tuberculosis (TB) is still a challenging worldwide health problem and mycobacterium tuberculosis (MTB) remains one of the most deadly human pathogens. TB is the second leading infectious cause of mortality today behind only HIV/AIDS. The impetus for developing new structural classes of antituberculosis drugs comes from the emergence of multi-drug resistant (MDR) strains. The development of MDR strains to commonly used drugs is due to, longer durations of therapy as results of resistance, and the resurgence of the disease in immune compromised patients. Therefore, there is an urgent need to explore new antitubercular (anti-TB) agents. Ironically, the low number of potentially new chemical entities which can act as anti-TB candidates is of great importance at present situation. Considering the severity of the problem, WHO has prepared a strategic plan in Berlin declaration 2007 to stop TB, globally. Among the oxygen heterocycles, coumarin derivatives are important motifs, which can be widely found in many natural products, and many of them displaying diverse biological activities. This spectacular spectrum of applications has intrigued organic and medicinal chemists for decades to explore the natural coumarins or their synthetic analogs for their applicability as anti-TB drugs. To pave the way for the future research, there is a need to collect the latest information in this promising area. In the present review, we collated published reports on coumarin derivatives to shed light on the insights on different types of methods reported for their preparations, characterizations and anti-TB applications, so that its full therapeutic potential class of compounds can be utilized for the treatment of tuberculosis. Therefore, the objective of this review is to focus on important coumarin analogs with anti-TB activities, and structure-activity relationships (SAR) for designing the better anti-TB agents. It is hoped that, this review will be helpful for new thoughts in the quest for rational designs of more active and less toxic coumarin-based anti-TB drugs.

Recent progress on pyrazole scaffold-based antimycobacterial agents

New and reemerging infectious diseases will continue to pose serious global health threats well into the 21st century and according to the World Health Organization report, these are still the leading cause of death among humans worldwide. Among infectious diseases, tuberculosis claims approximately 2 million deaths per year worldwide. Also, agents that reduce the duration and complexity of the current therapy would have a major impact on the overall cure rate. Due to the development of resistance to conventional antibiotics there is a need for new therapeutic strategies to combat Mycobacterium tuberculosis. Subsequently, there is an urgent need for the development of new drug candidates with newer targets and alternative mechanism of action. In this perspective, pyrazole, one of the most important classes of heterocycles, has been the topic of research for thousands of researchers all over the world because of its wide spectrum of biological activities. To pave the way for future research, there is a need to collect the latest information in this promising area. In the present review, we have collated published reports on the pyrazole core to provide an insight so that its full therapeutic potential can be utilized for the treatment of tuberculosis. In this article, the possible structure-activity relationship of pyrazole analogs for designing better antituberculosis (anti-TB) agents has been discussed and is also helpful for new thoughts in the quest for rational designs of more active and less toxic pyrazole-based anti-TB drugs.