Photooxidation of Other B-Vitamins as Sensitized by Riboflavin

Autor(es)

Arrivetti, Leandro de O. R. ^[1] ; Scurachio, Regina S. ^[1] ; Santos, Willy G. ^[1] ; Papa, Thiago B. R. ^[1] ; Skibsted, Leif H. ^[2] ; Cardoso, Daniel R. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

^[2] Univ Copenhagen, Dept Food Sci, DK-1958 Frederiksberg C - Denmark

• Tipo de documento: Artigo Científico
• Fonte: Journal of Agricultural and Food Chemistry; v. 61, n. 31, p. 7615-7620, AUG 7 2013.
• Citações Web of Science: 4

Resumo

Pyridoxal phosphate (PLP) was found to deactivate triplet-excited riboflavin (Rib) in aqueous solution with a deactivation constant of 3.0 +/- 0.1 X 10(8) L mol(-1) s(-1) at 25 degrees C. Likewise, PLP was found to quench the fluorescence emission of (1)Rib{*} with (1)k(q) = 1.0 +/- 0.1 x 10(11) L mol(-1) s(-1) as determined by steady state fluorescence. The rather high quenching constant suggests the formation of a ground state complex, which was further confirmed by time-resolved fluorescence measurements to yield a (1)Rib{*} deactivation constant of 3.4 +/- 0.4 x 10(10) L mol(-1) s(-1). Triplet quenching is assigned as one-electron transfer rather than hydrogen-atom transfer from PLP to (3)Rib{*}, as the reaction quantum yield, Phi = 0.82, is hardly influenced by solvent change from water to D2O, Phi = 0.78. Neither biotin nor niacin deactivates the singlet- or triplet-excited riboflavin as it is expected from their higher oxidation potentials E > 2 V vs NHE. (AU)

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