RESUMO
The chikungunya virus (CHIKV) has produced epidemic outbreaks of significant public health impact. The clinical symptoms of this disease are fever, polyarthralgia, and skin rash, generally self-limiting, although patients may develop a chronic disabling condition or suffer lethal complications. Unfortunately, there is no specific treatment or vaccine available. Thus, the search for effective therapies to control CHIKV infection is an urgent need. This study evaluated the antiviral activity of flavonoids isolated from Marcetia taxifolia by in vitro and in silico analysis. Cytotoxicity of compounds was determined by MTT assay and viral load was assessed in cell substrates supernatants by plaque-forming and RT-qPCR assays. Selected molecules were analyzed by molecular docking assays. Myricetin 3-rhamnoside (MR) and myricetin 3-(6-rhamnosylgalactoside) (MRG) were tested for antiviral assays and analyzed by the TCID50 method and RT-qPCR. MR exhibited dose-dependent antiviral activity, reducing viral titer at concentrations of 150-18.8 µg/mL by at least 1-log. Similarly, MRG showed a significant decrease in viral titer at concentrations of 37.5, 9.4, and 2.3 µg/mL. RT-qPCR analysis also displayed a substantial reduction of CHIKV RNA for both flavonoids. Furthermore, molecular docking of the selected flavonoids proposed the nsP3 macrodomain as a possible target of action. Our study reveals that MR and MRG could be considered promising anti-CHIKV therapeutic agents. Molecular modeling studies showed MR and MRG ligands with a high affinity for the N-terminal region of the nsP3 macrodomain, postulating them as a potential target of action for the CHIKV control.
RESUMO
BACKGROUND: The rapidly widespread SARS-CoV-2 infection has affected millions worldwide, thus becoming a global health emergency. Although vaccines are already available, there are still new COVID-19 cases daily worldwide, mainly due to low immunization coverage and the advent of new strains. Therefore, there is an utmost need for the discovery of lead compounds to treat COVID-19. OBJECTIVE: Considering the relevance of the SARS-CoV-2 MPRO in viral replication and the role of the isoquinoline moiety as a core part of several biologically relevant compounds, this study aimed to identify isoquinoline-based molecules as new drug-like compounds, aiming to develop an effective coronavirus inhibitor. METHODS: 274 isoquinoline derivatives were submitted to molecular docking interactions with SARS-CoV-2 MPRO (PDB ID: 7L0D) and drug-likeness analysis. The five best-docked isoquinoline derivatives that did not violate any of Lipinski's or Veber's parameters were submitted to ADMET analysis and molecular dynamics (MD) simulations. RESULTS: The selected compounds exhibited docking scores similar to or better than chloroquine and other isoquinolines previously reported. The fact that the compounds interact with residues that are pivotal for the enzyme's catalytic activity, and show the potential to be orally administered makes them promising drugs for treating COVID-19. CONCLUSION: Ultimately, MD simulation was performed to verify ligand-protein complex stability during the simulation period.
