Identification of sulphonamide-tethered N-((triazol-4-yl)methyl)isatin derivatives as inhibitors of SARS-CoV-2 main protease

Identification of new anti-mycobacterial agents based on quinoline-isatin hybrids targeting enoyl acyl carrier protein reductase (InhA)

Tuberculosis (TB) is a global issue that poses a significant economic burden as a result of the ongoing emergence of drug-resistant strains. The urgent requirement for the development of novel antitubercular drugs can be addressed by targeting specific enzymes. One such enzyme, Mycobacterium tuberculosis (MTB) enoyl-acyl carrier protein (enoyl-ACP) reductase (InhA), plays a crucial role in the survival of the MTB bacterium. In this research study, a series of hybrid compounds combining quinolone and isatin were synthesized and assessed for their effectiveness against MTB, as well as their ability to inhibit the activity of the InhA enzyme in this bacterium. Among the compounds tested, 7a and 5g exhibited the most potent inhibitory activity against MTB, with minimum inhibitory concentration (MIC) values of 55 and 62.5 µg/mL, respectively. These compounds were further evaluated for their inhibitory effects on InhA and demonstrated significant activity compared to the reference drug Isoniazid (INH), with IC50 values of 0.35 ± 0.01 and 1.56 ± 0.06 µM, respectively. Molecular docking studies investigated the interactions between compounds 7a and 5g and the target enzyme, revealing hydrophobic contacts with important amino acid residues in the active site. To further confirm the stability of the complexes formed by 5g and 7a with the target enzyme, molecular dynamic simulations were employed, which demonstrated that both compounds 7a and 5g undergo minor structural changes and remain nearly stable throughout the simulated process, as assessed through RMSD, RMSF, and Rg values.

Discovery of Pyrano[2,3-c]pyrazole Derivatives as Novel Potential Human Coronavirus Inhibitors: Design, Synthesis, In Silico, In Vitro, and ADME Studies

The SARS-CoV-2 pandemic at the end of 2019 had major worldwide health and economic consequences. Until effective vaccination approaches were created, the healthcare sectors endured a shortage of operative treatments that might prevent the infection's spread. As a result, academia and the pharmaceutical industry prioritized the development of SARS-CoV2 antiviral medication. Pyranopyrazoles have been shown to play a prominent function in pharmaceutical chemistry and drug sighting because of their significant bioactive properties. We provide herein a novel sequence of pyranopyrazoles and their annulated systems whose antiviral efficacy and cytotoxicity were explored versus human coronavirus 229E (HCoV-229E) Vero-E6 cell lines as a model for the Coronaviridae family. Fifteen synthetic congeners pointed out miscellaneous antiviral efficacies against HCoV-229E with variable inhibition degrees. Compound 18 showed a high selectivity index (SI = 12.6) that established spectacular inhibitory capacity against human coronavirus 229E. Compounds 6, 7, and 14 exposed moderate efficacies. Compounds 6, 7, 14, and 18 exhibited substantial antiviral action through the replication phase with reduction percentages extending from 53.6%, 60.7%, and 55% to 82.2%, correspondingly. Likewise, when assessed to the positive control tipranavir (88.6%), the inhibitory efficiency of compounds 6, 7, 14, and 18 versus the SARS-CoV2 Mpro provided high percentages of 80.4%, 73.1%, 81.4% and up to 84.5%, respectively. In silico studies were performed to investigate further the biological activity and the target compounds' physical and chemical features, including molecular dynamic (MD) simulations, protein-ligand docking, ADME studies, and density functional theory (DFT) calculations. These inquiries demonstrated that this series of metabolically stable pyranopyrazoles and their annulated systems are effective human coronavirus inhibitors that inhibit the viral Mpro protein and may have emerged as a novel COVID-19 curative option.

Novel indolinone-tethered benzothiophenes as anti-tubercular agents against MDR/XDR M. tuberculosis: Design, synthesis, biological evaluation and in vivo pharmacokinetic study

Joining the global effort to eradicate tuberculosis, one of the deadliest infectious killers in the world, we disclose in this paper the design and synthesis of new indolinone-tethered benzothiophene hybrids 6a-i and 7a-i as potential anti-tubercular agents. The MICs were determined in vitro for the synthesized compounds against the sensitive M. tuberculosis strain ATCC 25177. Potent compounds 6b, 6d, 6f, 6h, 7a, 7b, 7d, 7f, 7h and 7i were furtherly assessed versus resistant MDR-TB and XDR-TB. Structure activity relationship investigation of the synthesized compounds was illustrated, accordingly. Superlative potency was unveiled for compound 6h (MIC = 0.48, 1.95 and 7.81 µg/mL for ATCC 25177 sensitive TB strain, resistant MDR-TB and XDR-TB, respectively). Moreover, validated in vivo pharmacokinetic study was performed for the most potent derivative 6h revealing superior pharmacokinetic profile over the reference drug. For further exploration of the anti-tubercular mechanism of action, molecular docking was carried out for the former compound in DprE1 active site as one of the important biological targets of TB. The binding mode and the docking score uncovered exceptional binding when compared to the co-crystallized ligand suggesting that it maybe the underlying target for its outstanding anti-tubercular potency.

Fragment-based screening targeting an open form of the SARS-CoV-2 main protease binding pocket

To identify starting points for therapeutics targeting SARS-CoV-2, the Paul Scherrer Institute and Idorsia decided to collaboratively perform an X-ray crystallographic fragment screen against its main protease. Fragment-based screening was carried out using crystals with a pronounced open conformation of the substrate-binding pocket. Of 631 soaked fragments, a total of 29 hits bound either in the active site (24 hits), a remote binding pocket (three hits) or at crystal-packing interfaces (two hits). Notably, two fragments with a pose that was sterically incompatible with a more occluded crystal form were identified. Two isatin-based electrophilic fragments bound covalently to the catalytic cysteine residue. The structures also revealed a surprisingly strong influence of the crystal form on the binding pose of three published fragments used as positive controls, with implications for fragment screening by crystallography.

Leveraging SARS-CoV-2 Main Protease (Mpro) for COVID-19 Mitigation with Selenium-Based Inhibitors

The implementation of innovative approaches is crucial in an ongoing endeavor to mitigate the impact of COVID-19 pandemic. The present study examines the strategic application of the SARS-CoV-2 Main Protease (Mpro) as a prospective instrument in the repertoire to combat the virus. The cloning, expression, and purification of Mpro, which plays a critical role in the viral life cycle, through heterologous expression in Escherichia coli in a completely soluble form produced an active enzyme. The hydrolysis of a specific substrate peptide comprising a six-amino-acid sequence (TSAVLQ) linked to a p-nitroaniline (pNA) fragment together with the use of a fluorogenic substrate allowed us to determine effective inhibitors incorporating selenium moieties, such as benzoselenoates and carbamoselenoates. The new inhibitors revealed their potential to proficiently inhibit Mpro with IC50-s in the low micromolar range. Our study contributes to the development of a new class of protease inhibitors targeting Mpro, ultimately strengthening the antiviral arsenal against COVID-19 and possibly, related coronaviruses.