Indole-fused spirochromenes as potential anti-tubercular agents: design, synthesis and in vitro evaluation

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.

Identification of novel DNA gyrase inhibitor by combined pharmacophore modeling, QSAR analysis, molecular docking, molecular dynamics, ADMET and DFT approaches

DNA gyrase, an ATP-dependent enzyme, plays a critical role in DNA replication, transcription, and recombination in Mycobacterium tuberculosis (MTB). While fluoroquinolones are effective antibacterial agents targeting DNA gyrase, their clinical use is often limited due to side effects and the emergence of bacterial resistance. In this study, we developed a quantitative structure-activity relationship (QSAR) model to predict the anti-tubercular activity of Quinoline-Aminopiperidine derivatives targeting the DNA gyrase enzyme, using a dataset of 48 compounds obtained from the literature. The QSAR model was validated using both internal and external validation metrics. Model 4, the best predictive model, demonstrated a strong fit with an R² of 0.8393, an adjusted R² (R²adj) of 0.8010, and a lack of fit (LOF) parameter of 0.0626. The QSAR results revealed that DNA gyrase inhibition is significantly influenced by factors such as partition coefficient, molecular flexibility, hydrogen bonding potential, and the presence of fluorine atoms. Twelve quinoline-aminopiperidine derivatives were designed, and their anti-tubercular activity was predicted using QSAR model-4. These compounds were further assessed for pharmacokinetic properties, toxicity, and binding affinity to DNA gyrase. Pharmacophore modeling was also performed and validated using MOE software. The final pharmacophore model includes the features of two aromatic hydrophobic features, one hydrogen bond acceptor, and one hydrogen bond donor. The results indicated that designed compounds QA-3 and dataset compounds C-34 exhibit favorable drug-likeness properties. Molecular dynamics simulations confirmed the stable binding of compounds QA-3 and C-34 to the DNA gyrase protein, highlighting their potential as promising anti-tubercular agents. The developed QSAR Model-4 will facilitate the prediction of anti-tubercular activity in Quinoline-Aminopiperidine derivatives.

Quantitative structure activity relationship (QSAR) modeling study of some novel thiazolidine 4-one derivatives as potent anti-tubercular agents

This study aims to develop a QSAR model for Antitubercular activity. The quantitative structure-activity relationship (QSAR) approach predicted the thiazolidine-4-ones derivative's Antitubercular activity. For the QSAR study, 53 molecules with Antitubercular activity on H37Rv were collected from the literature. Compound structures were drawn by ACD/Labs ChemSketch. The energy minimization of the 2D structure was done using the MM2 force field in Chem3D pro. PaDEL Descriptor software was used to construct the molecular descriptors. QSARINS software was used in this work to develop the 2D QSAR model. A series of thiazolidine 4-one with MIC data were taken from the literature to develop the QSAR model. These compounds were split into a training set (43 compounds) and a test set (10 compounds). The PaDEL software calculated 2300 descriptors for this series of thiazolidine 4-one derivatives. The best predictive Model 4, which has R2 of 0.9092, R2adj of 0.8950 and LOF parameter of 0.0289 identify a preferred fit. The QSAR study resulted in a stable, predictive, and robust model representing the original dataset. In the QSAR equation, the molecular descriptor of MLFER_S, GATSe2, Shal, and EstateVSA 6 positively correlated with Antitubercular activity. While the SpMAD_Dzs 6 is negatively correlated with Antitubercular activity. The high polarizability, Electronegativities, Surface area contributions and number of Halogen atoms in the thiazolidine 4-one derivatives will increase the Antitubercular activity.

Synthesis, biological activity of newly designed sulfonamide based indole derivative as anti-microbial agent

Background

In medicinal chemistry, indole and its derivative play an important role. Indole is gaining a lot of importance in medicinal chemistry due to its physiological activity which includes anticancer, antitubercular, antimicrobial, antiviral, antimalarial, anti-inflammatory activities, antileishmanial agents, anti-cholinesterase, and enzyme inhibitory. The spread of antimicrobial resistance becomes a threat to both humans and animals. Antimicrobial resistance has been declared in the top 10 global major health risks by WHO including reported data of 2020 of AMR with 3,106,002 confirmed infections in humans across 70 countries.

Result

In this present work some new sulfonamide-based indole derivatives were synthesized by using 1H-indole -2 carboxylic acid as a starting material. The structure of all synthesized sulfonamide-based indole derivatives was confirmed by 1H NMR and LCMS Spectroscopy.

Conclusion

All the synthesized compounds were screened for anti-microbial activity against Gram Positive Staphylococcus aureus, Bacillus megaterium, and Gram Negative Klebsiella pneumonia, Escherichia coli, Salmonellatyphiae, Shigella sp., Enterobacter aerogenes. Among gram-positive Staphylococcus aureus, and Bacillus megaterium. The compound shows activity against Staphylococcus aureus, and among all gram-negative bacteria against Klebsiella pneumonia shows good activity.

An insight into the recent developments in anti-infective potential of indole and associated hybrids

Prevention, accurate diagnosis, and effective treatment of infections are the main challenges in the overall management of infectious diseases. The best example is the ongoing SARs-COV-2(COVID-19) pandemic; the entire world is extremely worried about at present. Interestingly, heterocyclic moieties provide an ideal scaffold on which suitable pharmacophores can be designed to construct novel drugs. Indoles are amongst the most essential class of heteroaromatics in medicinal chemistry, which are ubiquitous across natural sources. The aforesaid derivatives have become invaluable scaffolds because of their wide spectrum therapeutic applications. Therefore, many researchers are focused on the design and synthesis of indole and associated hybrids of biological relevance. Hence, in the present review, we concisely discuss the indole containing natural sources, marketed drugs, clinical candidates, and their biological activities like antibacterial, antifungal, anti-TB, antiviral, antimalarial, and anti-leishmanial activities. The structure-activity relationships study of indole derivatives is also presented for a better understanding of the identified structures. The literature data presented for the anti-infective agents herein covers largely for the last twelve years.