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.

A 3-alkylpyridine-bearing alkaloid exhibits potent antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) with no detectable resistance.

Staphylococcus aureus is a Gram-positive bacterium responsible for a wide variety of infectious diseases, and its methicillin-resistant isolates pose a serious worldwide public health risk. New drugs are urgently needed for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. Here, we evaluated the antibacterial activity of five 3-alkyl-pyridinic analogs against MRSA and, of these compounds, compound 6 showed promising antibacterial activity against Staphylococcus with minimum inhibitory concentration (MIC) ranging from 0.98 to 3.9 µgmL-¹ . In addition, it exhibited a rapid bactericidal action, with complete elimination of MRSA after 6 h of incubation at 15.6 µgmL-¹ . Compound 6 had the ability to damage the bacterial membrane and induce cell lysis and, due to its action on the membrane, showed low resistance induction potential in vitro. In the combination study, compound 6 revealed an additive effect (FICI = 1) with vancomycin and ofloxacin and ciprofloxacin (FICI = 0.75) against MRSA, reducing the effective concentration of this antibiotic two-fold. The anti-staphylococcal activity of compound 6 was stable in the presence of different concentrations of NaCl (50, 200, and 400 µM), trypsin ( 1:500, 1:250) and under a variety of pH values (4, 5, 6, and 8); however, its binding to plasmatic proteins (i.e., albumin) was substantial. The previous exposure of MRSA to the compound was able to reduce the formation of bacterial biofilm and reduce the biomass of mature biofilms. Compound 6 showed low selectivity in vitro for MRSA USA 300 when compared to eukaryotic cells (epithelial, fibroblast, and red blood cells).