Z-FA-FMK for COVID-19

The SARS-CoV-2 main protease (Mpro) is initially synthesized as part of polyprotein precursors that undergo autoproteolysis to release the free mature Mpro. To investigate the autoprocessing mechanism in transfected mammalian cells, we examined several fusion precursors, with the mature SARS-CoV-2 Mpro along with the flanking amino acids (to keep the native substrate sequences) sandwiched between different tags. Our analyses revealed differential proteolysis kinetics at the N- and C-terminal cleavage sites. Particularly, N-terminal processing is differentially influenced by various upstream fusion tags (GST, sGST, CD63, and Nsp4) and amino acid variations at the N-terminal P1 position, suggesting that precursor catalysis is flexible and subject to complex regulation. Mutating Q to E at the N-terminal P1 position altered both precursor catalysis and the properties of the released Mpro. Interestingly, the wild-type precursors exhibited different enzymatic activities compared to those of the released Mpro, displaying much lower susceptibility to known inhibitors targeting the mature form. These findings suggest the precursors as alternative targets for antiviral development. Accordingly, we developed and validated a high-throughput screening (HTS)-compatible platform for functional screening of compounds targeting either the N-terminal processing of the SARS-CoV-2 Mpro precursor autoprocessing or the released mature Mpro through different mechanisms of action.

Drug repurposing is a rapid approach to identify therapeutics for the treatment of emerging infectious diseases such as COVID-19. To address the urgent need for treatment options, we carried out a quantitative high-throughput screen using a SARS-CoV-2 cytopathic assay with a compound collection of 8,810 approved and investigational drugs, mechanism-based bioactive compounds, and natural products. Three hundred and nineteen compounds with anti-SARS-CoV-2 activities were identified and confirmed, including 91 approved drugs and 49 investigational drugs. The anti-SARS-CoV-2 activities of 230 of these confirmed compounds, of which 38 are approved drugs, have not been previously reported. Chlorprothixene, methotrimeprazine, and piperacetazine were the three most potent FDA-approved drugs with anti-SARS-CoV-2 activities. These three compounds have not been previously reported to have anti-SARS-CoV-2 activities, although their antiviral activities against SARS-CoV and Ebola virus have been reported. These results demonstrate that this comprehensive data set is a useful resource for drug repurposing efforts, including design of new drug combinations for clinical trials for SARS-CoV-2.

The global spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the associated disease COVID-19, requires therapeutic interventions that can be rapidly identified and translated to clinical care. Traditional drug discovery methods have a >90% failure rate and can take 10 to 15 y from target identification to clinical use. In contrast, drug repurposing can significantly accelerate translation. We developed a quantitative high-throughput screen to identify efficacious agents against SARS-CoV-2. From a library of 1,425 US Food and Drug Administration (FDA)-approved compounds and clinical candidates, we identified 17 hits that inhibited SARS-CoV-2 infection and analyzed their antiviral activity across multiple cell lines, including lymph node carcinoma of the prostate (LNCaP) cells and a physiologically relevant model of alveolar epithelial type 2 cells (iAEC2s). Additionally, we found that inhibitors of the Ras/Raf/MEK/ERK signaling pathway exacerbate SARS-CoV-2 infection in vitro. Notably, we discovered that lactoferrin, a glycoprotein found in secretory fluids including mammalian milk, inhibits SARS-CoV-2 infection in the nanomolar range in all cell models with multiple modes of action, including blockage of virus attachment to cellular heparan sulfate and enhancement of interferon responses. Given its safety profile, lactoferrin is a readily translatable therapeutic option for the management of COVID-19.

The main protease (Mpro) plays a pivotal role in the replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is considered a highly conserved viral target. Disruption of the catalytic activity of Mpro produces a detrimental effect on the course of the infection, making this target one of the most attractive for the treatment of COVID-19. The current success of the SARS-CoV-2 Mpro inhibitor Nirmatrelvir, the first oral drug for the treatment of severe forms of COVID-19, has further focused the attention of researchers on this important viral target, making the search for new Mpro inhibitors a thriving and exciting field for the development of antiviral drugs active against SARS-CoV-2 and related coronaviruses.

In this study, we present the highly efficient and rapid synthesis of substituted dihydropyrimidinone derivatives through an ultrasound-accelerated approach. We utilize copper ferrite (CuFe2O4) magnetic nanoparticles as heterogeneous catalysts, employing the well-known Biginelli reaction, under solvent-free conditions. The impact of the solvent, catalyst amount, and catalyst type on the reaction performance is thoroughly investigated. Our method offers several notable advantages, including facile catalyst separation, catalyst reusability for up to three cycles with the minimal loss of activity, a straightforward procedure, mild reaction conditions, and impressive yields, ranging from 79% to 95%, within short reaction times of 20 to 40 min. Furthermore, in the context of fighting COVID-19, we explore the potential of substituted dihydropyrimidinone derivatives as inhibitors of three crucial SARS-CoV-2 proteins. These proteins, glycoproteins, and proteases play pivotal roles in the entry, replication, and spread of the virus. Peptides and antiviral drugs targeting these proteins hold great promise in the development of effective treatments. Through theoretical molecular docking studies, we compare the binding properties of the synthesized dihydropyrimidinone derivatives with the widely used hydroxychloroquine molecule as a reference. Our findings reveal that some of the tested molecules exhibit superior binding characteristics compared to hydroxychloroquine, while others demonstrate comparable results. These results highlight the potential of our synthesized derivatives as effective inhibitors in the fight against SARS-CoV-2.