title: Light-induced byproducts of vitamin C in multivitamin solutions.
abstract: BACKGROUND
  When solutions of multivitamin preparations (MVPs) are exposed to light, H(2)O(2) as well as organic peroxides are generated and the concentration of vitamin C decreases. The aim of this study was to determine, using mass spectrometry, whether the generation of oxidative byproducts of vitamin C, such as dehydroascorbate (DHA) and 2,3-diketogulonic acid (DKG), accounted for the reported decrease in ascorbic acid in MVPs exposed to light.
  
  
  METHODS
  Mass spectrometry was used to document the formation of byproducts of ascorbic acid in solutions containing a MVP, vitamin C + riboflavin, and vitamin C + H(2)O(2) + Fe(2+). The involvement of ascorbic acid and H(2)O(2) in the formation of organic peroxides was tested by measuring peroxide concentrations in solutions containing H(2)O(2) with or without ascorbic acid and with or without Fe(2+) before and after addition of catalase.
  
  
  RESULTS
  The loss of ascorbic acid in photo-exposed MVPs was associated with the concomitant generation of byproducts different from DHA and DKG. Among them, one mass fingerprint was particularly observed with solutions of vitamin C + riboflavin exposed to ambient light as well as with the solution of vitamin C + H(2)O(2) + Fe(2+), suggesting a Fenton-like reaction. This fingerprint was associated with the formation of catalase-resistant peroxides.
  
  
  CONCLUSIONS
  Exposure of MVPs to light leads to the rapid loss of ascorbic acid and generation of specific byproducts that differ from DHA and DKG. The conversion of vitamin C into byproducts could be of biological importance in accounting for the decrease in ascorbic acid concentrations and the generation of organic peroxides in light-exposed MVPs.
authors.affiliation: Research Centre and Pediatric Department, Sainte-Justine Hospital, University of Montreal, Montreal, Quebec, Canada. jean-claude.lavoie@umontreal.ca
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Lavoie
authors.forename: Philippe
authors.initials: P
authors.lastname: Chessex
authors.forename: Thérèse
authors.initials: T
authors.lastname: Rouleau
authors.forename: Diane
authors.initials: D
authors.lastname: Migneault
authors.forename: Blandine
authors.initials: B
authors.lastname: Comte
mesh_terms: D015083:2,3-Diketogulonic Acid / Q000032:analysis; D001205:Ascorbic Acid / Q000737:chemistry / Q000528:radiation effects; D003683:Dehydroascorbic Acid / Q000032:analysis; D004356:Drug Storage; D008027:Light; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D010545:Peroxides / Q000032:analysis; D019999:Pharmaceutical Solutions; D014815:Vitamins / Q000737:chemistry / Q000528:radiation effects*
chemical_list: D010545:Peroxides; D019999:Pharmaceutical Solutions; D014815:Vitamins; D015083:2,3-Diketogulonic Acid; D001205:Ascorbic Acid; D003683:Dehydroascorbic Acid