Development of 2-chloroquinoline based heterocyclic frameworks as dual inhibitors of SARS-CoV-2 MPro and PLPro.

Evolution of new variants of SARS-CoV-2 warrant the need for the continued efforts in identifying target-oriented new drugs. Dual targeting agents against MPro and PLPro not only overcome the incomplete efficacy but also the drug resistance, which is common problem. Since both these are cysteine proteases, we designed 2-chloroquinoline based molecules with additional imine moiety in the middle as possible nucleophilic warheads. In the first round of design and synthesis, three molecules (C3, C4 and C5) inhibited (Ki < 2 µM) only MPro by binding covalently to C145 and one molecule (C10) inhibited both the proteases non-covalently (Ki < 2 µM) with negligible cytotoxicity. Further conversion of the imine in C10 to azetidinone (C11) improved the potency against both the enzymes in the nanomolar range (820 nM against MPro and 350 nM against PLPro) with no cytotoxicity. Conversion of imine to thiazolidinone (C12), reduced the inhibition by 3-5 folds against both the enzymes. Biochemical and computational studies suggest that C10-C12 bind in the substrate binding pocket of MPro and in the BL2 loop of the PLPro. Since these dual inhibitors have least cytotoxicity, they could be further explored as therapeutics against the SARS-CoV-2 and other analogous viruses.

Anti-inflammatory and antioxidant activities of Gymnema Sylvestre extract rescue acute respiratory distress syndrome in rats via modulating the NF-κB/MAPK pathway.

Acute respiratory distress syndrome (ARDS) is one of the major causes of mortality in COVID-19 patients, due to limited therapeutic options. This prompted us to explore natural sources to mitigate this condition. Gymnema Sylvestre (GS) is an ancient medicinal plant known to have various therapeutic effects. This investigation examined the therapeutic effect of hydroalcoholic extract of Gymnema Sylvestre (HAEGS) against lipopolysaccharide (LPS)-induced lung injury and ARDS in in vitro and in vivo models. UHPLC-HRMS/GC-MS was employed for characterizing the HAEGS and identified several active derivatives including gymnemic acid, gymnemasaponins, gymnemoside, gymnemasin, quercetin, and long fatty acids. Gene expression by RT-qPCR and DCFDA analysis by flow cytometry revealed that several inflammatory cytokine/chemokine, cell injury markers, and reactive oxygen species (ROS) levels were highly upregulated in LPS control and were significantly reduced upon HAEGS treatment. Consistent with the in vitro studies, we found that in LPS-induced ARDS model, pre-treatment with HAEGS significantly suppressed the LPS-induced elevation of inflammatory cell infiltrations, cytokine/chemokine marker expression, ROS levels, and lung injury in a dose-dependent manner. Further mechanistic studies demonstrated that HAEGS suppressed oxidative stress by modulating the NRF2 pathway and ameliorated the ARDS through the NF-κB/MAPK signalling pathway. Additional fractionation results revealed that fraction 6 which has the exclusive composition of gymnemic acid derivatives showed better anti-inflammatory effects (inhibition of IL-6 and IL-1ß) at lower concentrations compared to HAEGS. Overall, HAEGS significantly mitigated LPS-induced lung injury and ARDS by targeting the NF-κB/MAPK signalling pathway. Thus, our work unravels the protective role of HAEGS for the first time in managing ARDS.

Identification and characterization of degradation products of Remdesivir using liquid chromatography/mass spectrometry

Remdesivir (RDV), a nucleoside analogue prodrug, is used to treat viral diseases including COVID-19. The drug (RDV) was stressed under acidic, basic and neutral hydrolysis, oxidation, photolysis, and thermal conditions according to the International Council for Harmonisation (ICH) prescribed guidelines Q1A (R2). A total of nine degradation products were formed under acidic (DP1-DP5), basic (DP5-DP8) and neutral (DP5) hydrolysis, and oxidation (DP9) stress conditions, whereas the drug was found to be stable under thermal and photolytic stress conditions. The structures of the degradation products were elucidated by using a simple and rapid ultra high-performance liquid chromatography coupled to electrospray interface with quadrupole time-of-flight tandem mass spectrometer (UPLC/ESI-Q-TOF-MS/MS) method. [ABSTRACT FROM AUTHOR] Copyright of New Journal of Chemistry is the property of Royal Society of Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)