Anti-Mayaro virus activity of a hydroethanolic extract from Fridericia chica (Bonpl.) L. G. Lohmann leaves.

ETHNOPHARMACOLOGICAL RELEVANCE: Mayaro fever is a neglected tropical disease. The region of the most significant circulation of the Mayaro virus (MAYV) is the Amazon rainforest, situated in remote areas that are difficult to access and where medicine is scarce. Thus, the regional population uses plants as an alternative for the treatment of various diseases. Fridericia chica is an endemic plant of tropical regions used in traditional medicine to treat fever, malaise, inflammation, and infectious diseases such as hepatitis B. However, its antiviral activity is poorly understood. AIM OF THE STUDY: This study aimed to investigate the anti-MAYV activity of the hydroethanolic extract of the leaves of Fridericia chica (HEFc) in mammalian cells and its possible mechanism of action. MATERIALS AND METHODS: The antiviral activity of HEFc was studied using Vero cell lines against MAYV. The cytotoxicity and antiviral activity of the extract were evaluated by the 3-(4, 5- dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT) assay. The overall antiviral activity was confirmed by the plaque forming units (PFU) method. Then, the effects of HEFc on MAYV multiplication kinetics, virus adsorption, penetration, and post-penetration, and its virucidal activity were determined in Vero cells using standard experimental procedures. RESULTS: HEFc exerted a effect against viral infection in Vero cells at a non-cytotoxic concentration, and no virion was detected in the supernatant in a dose-dependent and selective manner. HEFc inhibited MAYV in the early and late stages of the viral multiplication cycle. The extract showed significant virucidal activity at low concentrations and did not affect adsorption or viral internalization stages. In addition, HEFc reduced virions at all post-infection times investigated. CONCLUSIONS: HEFc has good antiviral activity against MAYV, acting directly on the viral particles. This plant extract possesses an excellent and promising potential for developing effective herbal antiviral drugs.

Identification of Zika Virus NS2B-NS3 Protease Inhibitors by Structure-Based Virtual Screening and Drug Repurposing Approaches.

The NS2B-NS3 protease has been identified as an attractive target for drug development against Zika virus (ZIKV) and combined drug repurposing and structure-based virtual screening has improved the development of antiviral drugs. In this study, we performed a structure-based virtual screening of 1861 Food and Administration (FDA) approved drugs available in DrugBank by the selection and docking validation of crystal structure of ZIKV NS2B-NS3 protease (PDB ID 5H4I ) using Glide and DOCK 6 software. The antihistaminic chlorcyclizine (Grid score -24.8 kcal/mol) exhibited the most promising interaction with NS2B-NS3 protease in comparison to crystallography ligand (Grid score -15.6 kcal/mol) by interaction to Tyr161 by hydrophobic interactions in the binding site of NS2B-NS3 which is recognized as an important amino acid in substrate molecular recognition. Cytotoxicity and global antiviral activity assay in Vero cells by MTT method showed that chlorcyclizine reduced the ZIKV induced cytopathic effect (EC50 of 69.0 ± 7.3 µM and SI = 1.9), and explicit molecular dynamics simulations implemented on a NAMD program indicated great stability of chlorcyclizine in protease binding site, suggesting the repurposing of chlorcyclizine as a promising finding in anti-ZIKV drug development.