GC376 / Anivive - LARVOL DELTA

Structural Analysis of Inhibitor Binding to the Feline Enteric Coronavirus (FECV) Main Protease. (PubMed, Viruses) - "This study presents crystal structures of four clinically relevant inhibitors-GC376, PF-00835231, nirmatrelvir, and ibuzatrelvir-bound to Mpro from the feline coronavirus strain FECV-UU23. We therefore propose to incorporate sterically constrained, functionally tailored heterocyclic moieties at the P3 site of known inhibitors which can optimally engage Q187, P188, and S189 residues of the S4 loop. The findings presented enhance understanding of inhibitor specificity and reinforce the promise of these inhibitor scaffolds for developing antivirals against feline coronavirus strains, with possible applications in broad-spectrum coronavirus therapy."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Development of a Cell-Based Recombinant Green Fluorescent Protein Assay System for Generalized Discovery of Viral Protease Inhibitors. (PubMed, ACS Pharmacol Transl Sci) - "For proof of concept, we validated this method using two well-characterized SARS-CoV-2 3CLpro inhibitors, GC376 and ensitrelvir, to demonstrate its applicability for inhibitor screening. Our results indicate that the DIFF-rGFP assay is a safe, efficient, and reliable platform for identifying viral protease inhibitors with potential applications in accelerating antiviral drug discovery."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Glycosylated 18β-glycyrrhetinic acid derivatives as promising inhibitors of the SARS-CoV-2 main protease. (PubMed, RSC Adv) - "Biolayer interferometry revealed favorable binding affinities and reversible interactions with Mpro, while molecular docking demonstrated their stable binding conformations resembling that of GC376. These glycosides also showed improved predicted oral bioavailability and physicochemical profiles. Our findings support the potential of glycosylated 18β-GA derivatives as cost-effective and scalable antiviral candidates targeting SARS-CoV-2 Mpro."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Development of GFP-expressing infectious clones for PRRSV using TAR cloning for antiviral drug screening. (PubMed, Npj Viruses) - "Screening SARS-CoV-2 antivirals showed potent inhibition by the multitarget drug ribavirin, the polymerase inhibitors remdesivir and its metabolite GS-441524. Molnupiravir, targeting the polymerase by a different mechanism, showed reduced efficacy against PRRSV, while the protease inhibitor GC376 was ineffective...In contrast, structural divergence in proteases correlated with GC376's inefficacy. These findings underscore the utility of the TAR cloning for arterivirus engineering, with potential applications in vector vaccine development."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

A MAGNETIC BEAD-BASED FLUORESCENT SUBSTRATE FOR SENSITIVE ASSAY OF SARS-CoV-2 3C-LIKE PROTEASE ACTIVITY. (PubMed, Protein Expr Purif) - "The assay showed ∼50-fold greater sensitivity compared to SDS-PAGE and the inhibitory effect of GC376 for 3CLpro was also determined, with IC50 of 0.88 μM. Since the modular substrate design allows for substitution of the N-terminal domain and cleavage motif, our development of the substrate and assay could be expanded to other high-specificity proteases."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Antiviral and Immunomodulatory Effects of α-Mangostin Against Feline Infectious Peritonitis Virus: In Vitro Assay. (PubMed, Animals (Basel)) - "Drug combination studies using the ZIP model revealed enhanced cooperative effects when AMEs and α-MG were combined with GC-376 or GS-441524, with GC-376 combinations showing particularly strong synergistic potential. These findings suggest that α-MG and AMEs are promising candidates for FIPV treatment, either as monotherapy or in combination therapy. This study provides insights into developing novel therapeutic strategies to combat FIPV infections and offers a foundation for future veterinary antiviral drug development."

Journal • Preclinical • Infectious Disease • Novel Coronavirus Disease • IFNB1 • IL6 • TNFA

Enzyme kinetics model for the coronavirus main protease including dimerization and ligand binding. (PubMed, Biophys J) - "The reversible covalent inhibitor GC376 strongly induces dimerization and binds to the dimer with no cooperativity. In contrast, the fluorescent peptide substrate has a minor effect on dimerization but binds to the dimer with positive cooperativity. The biphasic concentration response curve occurs because compared to substrate, the inhibitor accelerates turnover in the opposite catalytic site."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

3CLpro of SARS-CoV-2 as a new target for bufadienolides: in silico and in vitro study. (PubMed, J Comput Aided Mol Des) - "In vitro enzymatic assays also confirmed these results, demonstrating that A and C exhibited potent inhibitory activity against 3CLpro with IC50 values of 1.37 µM and 2 µM, respectively, compared to the other bufadienolides; however, they were less active than the positive control GC376 (IC50 = 0.27 µM)...In silico ADME profiling also revealed good pharmacokinetic properties, indicating that bufadienolides A-F are lead compounds for further antiviral drug development. Taken together, our results support the hypothesis that bufadienolides are SARS-CoV-2 3CLpro inhibitors and elucidate their mechanism of action, thereby laying the foundation for potential therapeutic advances against COVID-19."

Journal • Preclinical • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Novel SARS-CoV-2 allosteric inhibitors that destabilize the Main Protease Mpro dimer. (PubMed, Int J Biol Macromol) - "Molecular modelling studies suggested that compounds 1 and 11 bind Mpro similarly to the allosteric inhibitor AT7519. Small-angle X-ray scattering studies revealed that 1 and 11 strongly shift Mpro equilibrium to the monomeric form, while the allosteric inhibitor pelitinib and the catalytic inhibitors nirmatrelvir and GC376 stabilize the dimer. Compounds 1 and 11 inhibited Mpro proteolytic activity in SARS-CoV-2 infected cells acting as allosteric inhibitors that stabilize the monomeric form. In conclusion, we validated an allosteric site in Mpro that could be exploited for the development of effective anti-SARS-CoV-2 antivirals targeting Mpro with a novel mechanism."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Strategy to overcome a nirmatrelvir resistance mechanism in the SARS-CoV-2 nsp5 protease. (PubMed, Sci Adv) - "E166V in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nsp5 protease confers strong resistance to the antiviral component of Paxlovid, nirmatrelvir (NIR), in passaging and clinical samples. Crystal structures reveal a steric clash between the rigid, bulky NIR tert-butyl group and the β-branched Val166, disrupting the covalent binding of NIR to the catalytic Cys145 and leading to high resistance in BA.1 and WA1 replicons. NIR-resistant replicons remained susceptible to GC376, which can still covalently bind Cys145 by avoiding a steric clash with Val166 through "wiggling and jiggling." Hence, strategic flexibility is a strategy that will help design second-generation antivirals against NIR-resistant viruses."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases • SPECC1

Development of a highly sensitive luciferase assay for intracellular evaluation of coronavirus Mpro activity. (PubMed, Front Microbiol) - "Additionally, the system proved suitable for evaluating and screening of antiviral compounds, including lufotrelvir, GC376, Nirmatrelvir, X77, MG-101, and the potential inhibitor Cynaroside. The ICMP system is not only an invaluable tool for the detection of live coronaviruses, but also for the discovery of antivirals against current and future pandemic coronaviruses."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Mycophenolate mofetil exerts broad-spectrum antiviral activity against coronaviruses including SARS-CoV-2. (PubMed, Virol J) - "MMF and MPA exerted broad-spectrum anti-coronavirus effects by inhibiting IMPDH activity. MMF had a synergistic antiviral effect when combined with other drugs, showing its potential clinical antiviral applications."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Multiview Deep Learning-Based Molecule Design and Structural Optimization Accelerates Inhibitor Discover. (PubMed, IEEE Trans Neural Netw Learn Syst) - "Moreover, case study results on targeted molecule generation for the SARS-CoV-2 main protease (Mpro) show that we successfully generate new small molecules with desired drug-like properties for the Mpro by integrating molecular docking into our model as a chemical priori, potentially accelerating the de novo design of COVID-19 drugs. Furthermore, we apply MEDICO to the structural optimization of three well-known Mpro inhibitors (N3, 11a, and GC376) and achieve ˜88% improvement compared with the origin inhibitors in their binding affinity to Mpro, demonstrating the application value of our model for the development of therapeutics for SARS-CoV-2 infection."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Exploring Possible Drug-Resistant Variants of SARS-CoV-2 Main Protease (Mpro) with Noncovalent Preclinical Candidate, Mpro61. (PubMed, ACS Bio Med Chem Au) - "We investigated their kinetic and structural properties, as well as resistance level to Mpro inhibitors: nirmatrelvir, GC376-a similar peptidomimetic for feline COVID infections, and our in-house-developed nonpeptidomimetic inhibitor Mpro61. The new orientation of the Ser1 suggested potential strategies for medicinal chemistry modifications of Mpro61 to enhance hydrogen-bonding interactions between these variants and Mpro61 derivatives. These studies provide critical insights into guiding the future design of additional Mpro61 derivatives that would potentially inhibit variants with the pan-drug-resistant E166V mutation."

Journal • Preclinical • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Computational and in vitro evaluation of sumac-derived ©Rutan compounds towards Sars-CoV-2 Mpro inhibition. (PubMed, Front Pharmacol) - "Initially, for the docking protocol validation, redocking of the co-crystal ligand GC-376* to the binding pocket of Mpro was carried out...All five components effectively interact with the catalytic pocket of Mpro and form stable complexes that allow the estimation of their inhibitory activity. Assay kit analyses revealed that Rutan and its components have effective anti-SARS-CoV-2 Mpro inhibitory activity."

Journal • Preclinical • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Enzyme kinetics model for the coronavirus main protease including dimerization and ligand binding. (PubMed, bioRxiv) - "The reversible covalent inhibitor GC376 strongly induces dimerization and binds to the dimer with no cooperativity. In contrast, the fluorescent peptide substrate has a minor effect on dimerization but binds to the dimer with positive cooperativity. The biphasic concentration response curve occurs because compared to substrate, the inhibitor accelerates turnover in the opposite catalytic site."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Peptide Aldehydes Incorporating Thiazol-4-yl Alanine Are Potent In Vitro Inhibitors of SARS-CoV-2 Main Protease. (PubMed, ACS Med Chem Lett) - "Continued research efforts have elucidated several peptidic small molecules like GC376, boceprevir, and nirmatrelvir with potent anticoronaviral activity bearing optimized amino acid side chain residues. We synthesized and tested several analogue chimeras of GC376 and boceprevir that have surrogate residues at the P1 and/or P2 position in order to further improve target binding. Both P1 variants with either a nonpolar cyclobutyl or polar thiazol-4-yl alanine resulted in low-micromolar to submicromolar Mpro inhibitors with strong antiviral activity in cell assays."

Journal • Preclinical • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

A Structural Investigation of the Interaction between a GC-376-Based Peptidomimetic PROTAC and Its Precursor with the Viral Main Protease of Coxsackievirus B3. (PubMed, Biomolecules) - "The inhibition activity assay showed inhibition potency in the micromolar range for GC-376 PROTAC and its precursor. Overall, we can conclude that the GC-376 PROTAC fits well within the binding sites of both proteases, demonstrating its potential as a broad-spectrum antiviral agent."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases • Targeted Protein Degradation

Design, Synthesis, Biological Evaluation and Molecular Docking Studies of New Thiazolidinone Derivatives as NNRTIs and SARS-CoV-2 Main Protease Inhibitors. (PubMed, Chem Biodivers) - "FDA approved Delavirdine bearing a sulfonamide moiety, while thiazolidinone has demonstrated significant anti-HIV activity as a core heterocycle or derivative of substituted heterocycles...Seven compounds showed good anti-HIV inhibitory activity, with two of them, C1 and C2 being better (IC50 0.18 μΜ & 0.12 μΜ respectively) than the reference drug nevirapine (IC50 0.31 μΜ). The evaluation of molecules to inhibit the main protease revealed that 6 of the synthesized compounds exhibited excellent to moderate activity with two of them (B4 and B10) having better IC50 values (0.15 & 0.19 μΜ respectively) than the reference inhibitor GC376 (IC50 0.439 μΜ). The docking studies is coincides with experimental results, showing good binding mode to both enzymes."

Journal • Human Immunodeficiency Virus • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

A Gaussia luciferase reporter assay for the evaluation of coronavirus Nsp5/3CLpro activity. (PubMed, Sci Rep) - "Proof-of-concept measurements confirmed that nirmatrelvir, GC376 and lopinavir inhibit SARS-CoV-2 Nsp5 function. Furthermore, the assay accurately predicted the impact of Nsp5 mutations on catalytic activity and inhibitor sensitivity. Overall, the reporter assay is suitable for evaluating viral protease activity."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases • SPECC1

SARS-CoV-2 Mpro inhibitor identification using a cellular gain-of-signal assay for high-throughput screening. (PubMed, SLAS Discov) - "The SARS2 main protease enzyme, Mpro (also called 3C-like protease, 3CLpro), is a bona fide drug target as evidenced by potent inhibition with nirmatrelvir and ensitrelvir, the active components of the drugs Paxlovid and Xocova, respectively...In this assay, Mpro inhibits expression of a luciferase reporter, and 8,777 small molecules were considered hits by causing a gain in luciferase activity 3x SD above the sample field activity (6.8% gain-of-signal relative to 100 µM GC376)...Importantly, 19/39 compounds (49%) re-tested positive in both SARS2 assays, including two previously reported Mpro inhibitors, demonstrating the efficacy of the overall screening strategy. This approach led to the rediscovery of known Mpro inhibitors such as calpain inhibitor II, as well as to the discovery of novel compounds that provide chemical information for future drug development efforts."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Taming the storm: potential anti-inflammatory compounds targeting SARS-CoV-2 MPro. (PubMed, Inflammopharmacology) - "Five of them exhibit high potency against MPro: GC-376, baicalein, naringenin, heparin, and carmofur, with IC50 values below 0.2 μM...They interact with residues from the catalytic dyad (His41 and Cys145) and/or with the oxyanion hole (Gly143, Ser144, and Cys145), which are pivotal for substrate recognition. The MPro SARS-CoV-2 inhibitors with potential anti-inflammatory activities present here could be optimized for maximum efficacy and safety and be explored as potential treatment of both mild and severe COVID-19."

Journal • Review • Infectious Disease • Inflammation • Novel Coronavirus Disease • Respiratory Diseases

SARS-CoV-2 replication and drug discovery. (PubMed, Mol Cell Probes) - "Notably, we discussed inhibition mechanisms of viral replication, involving and including inhibition of SARS-CoV-2 proteases (3C-like protease, 3CLpro or Papain-like protease, PLpro) by protease inhibitors such as Carmofur, Ebselen, and GRL017, polymerases (RNA-dependent RNA-polymerase, RdRp) by drugs like Suramin, Remdesivir, or Favipiravir, and proteins/peptides inhibiting virus-cell fusion and host cell replication pathways, such as Disulfiram, GC376, and Molnupiravir. When applicable, comparisons with SARS-CoV inhibitors approved for clinical use were made to provide further insights to understand molecular basics in inhibiting SARS-CoV-2 replication and draw conclusions for future drug discovery research."

Journal • Review • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Phytoconstituents of Citrus limon (Lemon) as Potential Inhibitors Against Multi Targets of SARS-CoV-2 by Use of Molecular Modelling and In Vitro Determination Approaches. (PubMed, ChemistryOpen) - "When compared with approved COVID-19 drugs such as Remdesivir, Ritonavir, Lopinavir, and Hydroxychloroquine, plant-based constituents such as Quercetin, Rutoside, Naringin, Eriocitrin, and Hesperidin. The IC50 value of the test compound was found to be Rutin -17.50 μM, Eriocitrin-37.91 μM, Naringin-39.58 μM, Hesperidine-140.20 μM, the standard inhibitory concentration of GC376 was 38.64 μM. The phytoconstituents showed important interactions with SARS-CoV-2 targets, and potential modifications could be beneficial for future development."

Journal • Preclinical • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Development of novel antivrial agents that induce the degradation of the main protease of human-infecting coronaviruses. (PubMed, Eur J Med Chem) - "By adapting the Mpro inhibitor GC376, we produced two novel PROTACs, P2 and P3, which showed relatively broad-spectrum activity against the human-infecting CoVs HCoV-229E, HCoV-OC43, and SARS-CoV-2...Furthermore, mechanistic binding studies demonstrated that P2 and P3 effectively targeted HCoV-229E, HCoV-OC43, and SARS-CoV-2 by degrading Mpro within cells in vitro. This study highlights the potential of PROTAC technology in the development of broad-spectrum anti-HCoVs agents, presenting a novel approach for dealing with future viral outbreaks, particularly those stemming from CoVs."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases • Targeted Protein Degradation