Photooxidation of other B-Vitamins as sensitized by Riboflavin

Leandro de O.R. Arrivetti, Regina S. Scurachio, Willy Santos, Thiago B.R. Papa, Leif Horsfelt Skibsted, Daniel R. Cardoso

5 Citationer (Scopus)

Abstract

Pyridoxal phosphate (PLP) was found to deactivate triplet-excited riboflavin (Rib) in aqueous solution with a deactivation constant of 3.0 ± 0.1 × 108 L mol-1 s-1 at 25 C. Likewise, PLP was found to quench the fluorescence emission of 1Rib* with 1kq = 1.0 ± 0.1 × 1011 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 1Rib* deactivation constant of 3.4 ± 0.4 × 1010 L mol-1 s-1. Triplet quenching is assigned as one-electron transfer rather than hydrogen-atom transfer from PLP to 3Rib, as the reaction quantum yield, Φ = 0.82, is hardly influenced by solvent change from water to D2O, Φ = 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.

OriginalsprogEngelsk
TidsskriftJournal of Agricultural and Food Chemistry
Vol/bind61
Udgave nummer31
Sider (fra-til)7615-7620
Antal sider6
ISSN0021-8561
DOI
StatusUdgivet - 7 aug. 2013

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