title: Quercetin and quercetin 3-O-glycosides from Bauhinia longifolia (Bong.) Steud. show anti-Mayaro virus activity.
abstract: BACKGROUND
  The arthropod-borne Mayaro virus (MAYV) causes 'Mayaro fever', a disease of medical significance, primarily affecting individuals in permanent contact with forested areas in tropical South America. Recently, MAYV has attracted attention due to its likely urbanization. Currently, there are no licensed drugs against most mosquito-transmitted viruses. Here, we investigated the in vitro anti-MAYV activity of the flavonoids quercetin and its derivatives from the Brazilian shrub Bauhinia longifolia (Bong.) Steud.
  
  
  METHODS
  Flavonoids were purified by chromatographic fractionation from leaf extracts of B. longifolia and chemically identified as quercetin and quercetin glycosides using spectroscopic techniques. Cytotoxicity of purified flavonoids and of EtOAc- and n-BuOH-containing flavonoid mixtures was measured by the dye-uptake assay while their antiviral activity was evaluated by a virus yield inhibition assay.
  
  
  RESULTS
  The following flavonoids were purified from B. longifolia leaves: non-glycosylated quercetin and its glycosides guaijaverin, quercitrin, isoquercitrin, and hyperin. EtOAc and n-BuOH fractions containing these flavonoids demonstrated the highest antiviral activity of all tested substances, while quercetin had the highest antiviral activity amongst purified flavonoids. Quercetin, EtOAc, or n-BuOH fractions inhibited MAYV production by more than 90% at 25 μg/mL, displaying a stronger antiviral effect than the licensed antiviral ribavirin. A mixture of the isomers isoquercitrin and hyperin had a modest antiviral effect (IC90 = 104.9), while guaijaverin and quercitrin did not show significant antiviral activity.
  
  
  CONCLUSIONS
  B. longifolia is a good source of flavonoids with anti-Mayaro virus activity. This is the first report of the activity of quercetin and its derivatives against an alphavirus.
authors.forename: Alda E
authors.initials: AE
authors.lastname: dos Santos
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Kuster
authors.forename: Kristie A
authors.initials: KA
authors.lastname: Yamamoto
authors.forename: Tiago S
authors.initials: TS
authors.lastname: Salles
authors.forename: Renata
authors.initials: R
authors.lastname: Campos
authors.forename: Marcelo D F
authors.initials: MD
authors.lastname: de Meneses
authors.forename: Márcia R
authors.initials: MR
authors.lastname: Soares
authors.affiliation: Microbiology Institute, Virology Department, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. davisf@micro.ufrj.br.
authors.forename: Davis
authors.initials: D
authors.lastname: Ferreira
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology*; D001103:Arboviruses / Q000187:drug effects*; D036481:Bauhinia / Q000737:chemistry*; D002522:Chlorocebus aethiops; D006027:Glycosides / Q000737:chemistry / Q000494:pharmacology*; D015394:Molecular Structure; D018515:Plant Leaves / Q000737:chemistry; D011794:Quercetin / Q000737:chemistry / Q000494:pharmacology*; D014709:Vero Cells
chemical_list: D000975:Antioxidants; D000998:Antiviral Agents; D006027:Glycosides; D011794:Quercetin