Anti-tubercular activity of novel class of spiropyrrolidine tethered indenoquinoxaline heterocyclic hybrids

A one-pot ultrasound-assisted regio and stereoselective synthesis of indenoquinoxaline engrafted spiropyrrolidines

A catalyst free ultrasound-assisted regio-/stereoselective modular approach was accomplished for the synthesis of highly constrained indenoquinoxaline engrafted spiro pyrrolidines from easily available substrates. This one-pot strategy utilizes 1,3-dipolar cycloaddition from a four component reaction of ninhydrin, 1,2-phenylenediamine, β-nitrostyrene and benzylamine or amino acids under ultrasound irradiation. The transformation is mild and operationally simple, providing architecturally complex fused spiro polycyclic heterocycles. This synthesis was confined to follow the group-assistant-purification (GAP) chemistry process, which can avoid chromatographic purifications and use of catalysts and allows easy access to a novel class of spiro engrafted polyheterocyclic scaffolds, which may be beneficial in biomedical research/materials science in the near future. This opens an era for the formation of a single exo product, when compared with reported protocols, by merely switching over reaction conditions to US irradiation.

Activity against Mycobacterium tuberculosis of a new class of spirooxindolopyrrolidine embedded chromanone hybrid heterocycles

A new class of structurally intriguing heterocycles embedded with spiropyrrolidine, oxindole and chromanones was prepared by regio- and stereoselectively in quantitative yields using an intermolecular tandem cycloaddition protocol. The compounds synthesized were assayed for their anti-mycobacterial activity against Mycobacterium tuberculosis (Mtb) H37Rv and isoniazid-resistant (katG and inhA promoter mutations) clinical Mtb isolates. Four compounds exhibited significant antimycobacterial activity against Mtb strains tested. In particular, a compound possessing a fluorine substituted derivative displayed potent activity at 0.39 μg mL-1 against H37Rv, while it showed 0.09 μg mL-1 and 0.19 μg mL-1 activity against inhA promoter and katG mutation isolates, respectively. A molecular docking study was conducted with the potent compound, which showed results that were consistent with the in vitro experiments.

The first-in-class pyrazole-based dual InhA-VEGFR inhibitors towards integrated antitubercular host-directed therapy

Several facets of the host response to tuberculosis have been tapped for clinical investigation, especially targeting angiogenesis mediated by VEGF signaling from infected macrophages. Herein, we rationalized combining the antiangiogenic effects of VEGFR-2 blockade with direct antitubercular InhA inhibition in single hybrid dual inhibitors as advantageous alternatives to the multidrug regimens. Inspired by expanded triclosans, the ether ligation of triclosan was replaced by rationalized linkers to assemble the VEGFR-2 inhibitors thematic scaffold. Accordingly, new series of 3-(p-chlorophenyl)-1-phenylpyrazole derivatives tethered to substituted ureas and their isosteres were synthesized, evaluated against Mycobacterium tuberculosis virulent cell line H37Rv, and assessed for their InhA inhibitory activities. The urea derivatives 8d and 8g exhibited the most promising antitubercular activity (MIC = 6.25 µg/mL) surpassing triclosan (MIC = 20 µg/mL) with potential InhA inhibition, thus identified as the study hits. Interestingly, both compounds inhibited VEGFR-2 at nanomolar IC50 (15.27 and 24.12 nM, respectively). Docking and molecular dynamics simulations presumed that 8d and 8g could bind to their molecular targets InhA and VEGFR-2 posing essential stable interactions shared by the reference inhibitors triclosan and sorafenib. Finally, practical LogP, Lipinski's parameters and in silico ADMET calculations highlighted their drug-likeness as novel leads in the arsenal against TB.

Design, synthesis, anti-mycobacterial activity, molecular docking and ADME analysis of spiroquinoxaline-1,2,4-oxadiazoles via [3 + 2] cycloaddition reaction under ultrasound irradiation

The development of anti-tuberculosis (anti-TB) drugs has become a challenging task in medicinal chemistry. This is because Mycobacterium tuberculosis (TB), the pathogen that causes tuberculosis, has an increasing number of drug-resistant strains, and existing medication therapies are not very effective. This resistance significantly demands new anti-TB drug profiles. Here, we present the design and synthesis of a number of hybrid compounds with previously known anti-mycobacterial moieties attached to quinoxaline, quinoline, tetrazole, and 1,2,4-oxadiazole scaffolds. A convenient ultrasound methodology was employed to attain spiroquinoxaline-1,2,4-oxadiazoles via [3 + 2] cycloaddition of quinoxaline Schiff bases and aryl nitrile oxides at room temperature. This approach avoids standard heating and column chromatography while producing high yields and shorter reaction times. The target compounds 3a-p were well-characterized, and their in vitro anti-mycobacterial activity (anti-TB) was evaluated. Among the screened compounds, 3i displayed promising activity against the Mycobacterium tuberculosis cell line H37Rv, with an MIC99 value of 0.78 µg/mL. However, three compounds (3f, 3h, and 3o) exhibited potent activity with MIC99 values of 6.25 µg/mL. To further understand the binding interactions, the synthesized compounds were docked against the tuberculosis protein 5OEQ using in silico molecular docking. Moreover, the most active compounds were additionally tested for their cytotoxicity against the RAW 264.7 cell line, and the cytotoxicity of compounds 3f, 3h, 3i, and 3o was 27.3, 28.9, 26.4, and 30.2 µg/mL, respectively. These results revealed that the compounds 3f, 3h, 3i, and 3o were less harmful to humans. Furthermore, the synthesized compounds were tested for ADME qualities, and the results suggest that this series is useful for producing innovative and potent anti-tubercular medicines in the future.

Recent synthetic strategies of spiro-azetidin-2-one, -pyrrolidine, -indol(one) and -pyran derivatives-a review

Spiro-heterocycles have received special attention in medicinal chemistry because of their promising biological activity. Over the years, many synthetic methodologies have been established for the construction of spirocyclic compounds. Spiro heterocycles such as spiro-azetidin-2-one, -pyrrolidine, -indol(one) and -pyran derivatives have been found to exhibit diversified biological and pharmacological activity in addition to their therapeutic properties. In view of these facts, we decided in this review to present representative synthetic approaches of the aforementioned spiro heterocycles, especially in the past 20 years.

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.

Azomethine Ylides-Versatile Synthons for Pyrrolidinyl-Heterocyclic Compounds

Azomethine ylides are nitrogen-based three-atom components commonly used in [3+2]-cycloaddition reactions with various unsaturated 2π-electron components. These reactions are highly regio- and stereoselective and have attracted the attention of organic chemists with respect to the construction of diverse heterocycles potentially bearing four new contiguous stereogenic centers. This review article complies the most important [3+2]-cycloaddition reactions of azomethine ylides with various olefinic, unsaturated 2π-electron components (acyclic, alicyclic, heterocyclic, and exocyclic ones) reported over the past two decades.

Antimicrobial activities of spirooxindolopyrrolidine tethered dicarbonitrile heterocycles against multidrug resistant nosocomial pathogens

BACKGROUND

Microbial infections together with rising drug resistance pose a threat to immunocompromised individual. In this perspective, compounds with spirooxindolopyrrolidine play a significant role in research on antimicrobial drug delivery research owing to their various pharmaceutical activities. Spiroheterocyclic compounds are present in number of medications as active motif due to their exceptional structural properties which enable for easy interaction with the protein of the biological target. Inspired by this biological precedent encouraged to synthesize a new class of dispirooxindole fused pyrrolidine heterocycles via a three-component cycloaddition strategy.

MATERIALS AND METHODS

The new class of structurally intriguing spirooxindolopyrrolidines were synthesized through three component cycloaddition process and the structure of products were assigned through spectroscopic analysis. The newly synthesized compounds were assessed for their antimicrobial sensitivity test with standard Kirby Bauer method with common drugs.

RESULTS

The structurally unexplored hybrid heterocycles fused spirooxindolopyrrolidine exhibited excellent antimicrobial activity against the common nosocomial microbial pathogens. Of four compounds, the compound bearing a chlorine atom on the aryl ring (4a) exhibited significant antimicrobial activity (zone of inhibition: 9.00 ± 1.00-17.00 ± 0.35 mm and MIC: 16.00-256.00 μg/mL) against selected nosocomial infection causing microbial pathogens. Hence, the compound 4a has been considered as an effective drug of interest in therapeutic field for compacting infectious diseases causing pathogens.

CONCLUSION

With an aim of developing more effective and economically more affordable antimicrobial leads with a unique mechanism of action, we have designed and synthesized structurally diverse spirooxindolopyrrolidine tethered hybrids that has been assayed against multidrug resistant nosocomial pathogens. The regioisomer having chloro substituted on the phenyl ring showed potent activity when compared to standard drug. Future studies are required to explicate the pharmacological properties of new hybrid heterocycles that have been synthesized in our laboratory for the novel therapeutic development.

Antimicrobial activities of novel class of dispirooxindolopyrrolidine grafted indanedione hybrid heterocycles against carbapenemase producing Klebsiella pneumoniae (CKP)

BACKGROUND

Aggressive antimicrobial infections together with an increasing in resistance to antimicrobial medications cause a threat to immunocompromised individual. In this context, spiro compounds play an important role in drug discovery research due to their diverse biological activities including antimicrobial activity which is well documented in literature, because of their unique structural properties allow for easy interaction with the target enzyme of the biological system. This biological precedent encouraged us to design and synthesis of novel dispirooxindolopyrrolidine hybrid heterocycles via multicomponent cycloaddition protocol.

MATERIALS AND METHODS

Novel class of dispirooxindolopyrrolidine hybrid heterocycles has been synthesized by multicomponent 1,3-dipolar cycloaddition methodology and the structure of the products was determined through spectroscopic analysis. The synthesized organic compounds were evaluated for their antimicrobial activities using sensitivity test with standard agar well diffusion method.

RESULTS

The synthesized new class of dispiropyrrolidine embedded indandione hybrids showed significant antimicrobial activity against carbapenemase producing Klebsiella pneumoniae (CKPs) isolated from hospital patients. Compound that possessing chlorine substituted on the aryl ring exhibited more potent antimicrobial activities and the zone of inhibitions was observed between 7.00 ± 0.09 and 18.40 ± 0.70 mm. The MIC value of compound 4b was 0.030 mg/mL against tested CKP.

CONCLUSION

A new class of dispiropyrrolidine heterocyclic hybrids were synthesized in good to excellent yield employing multicomponent 1,3-dipolar cycloaddition strategy. Among them, compounds bearing 4-chloro substituted on the aryl ring exhibited notable activity just equal to the standard drug, ciprofloxacin. Future studies are needed to elucidate the pharmacological properties of new compounds that were synthesized in our laboratory for the novel therapeutic development.

Quinoxaline Moiety: A Potential Scaffold against Mycobacterium tuberculosis

Background. The past decades have seen numerous efforts to develop new antitubercular agents. Currently, the available regimens are lengthy, only partially effective, and associated with high rates of adverse events. The challenge is therefore to develop new agents with faster and more efficient action. The versatile quinoxaline ring possesses a broad spectrum of pharmacological activities, ensuring considerable attention to it in the field of medicinal chemistry. Objectives. In continuation of our program on the pharmacological activity of quinoxaline derivatives, this review focuses on potential antimycobacterial activity of recent quinoxaline derivatives and discusses their structure-activity relationship for designing new analogs with improved activity. Methods. The review compiles recent studies published between January 2011 and April 2021. Results. The final total of 23 studies were examined. Conclusions. Data from studies of quinoxaline and quinoxaline 1,4-di-N-oxide derivatives highlight that specific derivatives show encouraging perspectives in the treatment of Mycobacterium tuberculosis and the recent growing interest for these scaffolds. These interesting results warrant further investigation, which may allow identification of novel antitubercular candidates based on this scaffold.

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.

Stereoselective synthesis and discovery of novel spirooxindolopyrrolidine engrafted indandione heterocyclic hybrids as antimycobacterial agents

Novel spirooxindolopyrrolidine embedded indandione heterocyclic hybrids were obtained in excellent yields via a regio- and stereoselective one-pot three component reaction between Baylis-Hillman adduct and non-stabilized azomethine ylides. The structure of newly synthesized compounds was elucidated through 1D and 2D spectroscopic data and the stereochemistry was determined by single crystal X-ray diffraction analysis. In vitro tubercular activity against Mycobacterium tuberculosis H37Rv using MABA assay reveals that the compound bearing chlorine substituted on the oxindole ring displayed the most potent activity with MIC 0.78 μg/mL and is two-fold active than the standard drug, ethambutol (MIC 1.56 μg/mL).

Recent advancement in the synthesis of diverse spiro-indeno[1,2-b]quinoxalines: a review

The nitrogen-containing indeno[1,2-b]quinoxaline ring is a privileged structurally fused active system and has notable applications in various fields of chemistry.

An expedient synthesis of novel spiro[indenoquinoxaline-pyrrolizidine]-pyrazole conjugates with anticancer activity from 1,5-diarylpent-4-ene-1,3-diones through the 1,3-dipolar cycloaddition/cyclocondensation sequence

A highly regio- and stereoselective two-stage route for the synthesis of spiro[indenoquinoxaline-pyrrolizidine]-pyrazole hybrids with anticancer activity has been developed.