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Updated: May 9, 2026

Inactivation of Pathogens via Visible-Light Photolysis of Riboflavin-5′-Phosphate
Published on: April 6, 2022
Photooxidation of other B-vitamins as sensitized by riboflavin
Leandro de O R Arrivetti1, Regina S Scurachio, Willy G Santos
1Instituto de Química de São Carlos, Universidade de São Paulo, Av. Trabalhador São Carlense 400, CP 780, CEP 13560-970, São Carlos-SP, Brazil.
Abstract:
Pyridoxal phosphate (PLP) was found to deactivate triplet-excited riboflavin (Rib) in aqueous solution with a deactivation constant of 3.0 ± 0.1 × 10(8) L mol(-1) s(-1) at 25 °C. Likewise, PLP was found to quench the fluorescence emission of (1)Rib* with (1)kq = 1.0 ± 0.1 × 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 × 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, 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.
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