title: The activity of propolis in the scavenging of vitamin B2-photogenerated ROS.
abstract: OBJECTIVE
  The study was focused on the activity of propolis from Amaicha del Valle, Argentina (ProAV) as a promoter and scavenger of Riboflavin (Rf)--photogenerated reactive oxygen species (ROS).
  
  
  METHODS
  Through a kinetic and mechanistic study, employing stationary and time-resolved photochemical and electrochemical techniques, the protecting activity of ProAV was investigated.
  
  
  RESULTS
  In the absence of light and Rf, ProAV exerted a relatively efficient inhibitory effect on 1,1-diphenyl-2-picrylhydrazyl radicals and acts as a protector of artificially promoted linoleic acid oxidation. Under aerobic visible-light-irradiation conditions, in the presence of Rf as the only light-absorber species, a complex picture of competitive processes takes place, starting with the quenching of singlet and triplet electronically excited states of Rf by ProAV. The species O2(1 g), O2(•-), H2O2, and OH(•) are generated and interact with ProAV.
  
  
  CONCLUSIONS
  ProAV behaves as an efficient ROS scavenger. It is scarcely photo-oxidized by interaction with the mentioned ROS. Quantitative results indicate that ProAV is even more resistant to photo-oxidation than the recognized antioxidant trolox. Two dihydroxychalcones, mostly present in the ProAV composition, are responsible for the protecting activity of the propolis.
authors.forename: Mariela
authors.initials: M
authors.lastname: González
authors.forename: María L
authors.initials: ML
authors.lastname: Tereschuk
authors.forename: Susana
authors.initials: S
authors.lastname: Criado
authors.forename: Eugenia
authors.initials: E
authors.lastname: Reynoso
authors.forename: Cecilia
authors.initials: C
authors.lastname: Challier
authors.forename: María Belén
authors.initials: MB
authors.lastname: Agüero
authors.forename: Lorena
authors.initials: L
authors.lastname: Luna
authors.forename: Gabriela
authors.initials: G
authors.lastname: Ferrrari
authors.forename: María P
authors.initials: MP
authors.lastname: Montaña
authors.forename: Norman A
authors.initials: NA
authors.lastname: García
mesh_terms: D000975:Antioxidants / Q000737:chemistry; D001713:Biphenyl Compounds / Q000737:chemistry; D047188:Chalcones / Q000737:chemistry; D002839:Chromans / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D008027:Light; D019787:Linoleic Acid / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D019800:Phenol / Q000737:chemistry; D010777:Photochemistry; D010782:Photolysis; D017319:Photosensitizing Agents / Q000737:chemistry; D010851:Picrates / Q000737:chemistry; D011401:Promoter Regions, Genetic; D011429:Propolis / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry*; D012256:Riboflavin / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000737:chemistry
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D047188:Chalcones; D002839:Chromans; D016166:Free Radical Scavengers; D017319:Photosensitizing Agents; D010851:Picrates; D017382:Reactive Oxygen Species; D019800:Phenol; D014364:Tryptophan; D011429:Propolis; D019787:Linoleic Acid; D006861:Hydrogen Peroxide; C004931:1,1-diphenyl-2-picrylhydrazyl; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; D010100:Oxygen; D012256:Riboflavin
keywords: Antioxidant; Photodegradation; Propolis; Vitamin B2 photogenerate