Photooxidation of Other B-Vitamins as Sensitized by Riboflavin

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.

Effect of UV Irradiation on the Nutritional Quality and Cytotoxicity of Apple Juice

“…Riboflavin is a very photosensitive vitamin and acts as a photosensitizer because of the presence of a double bond in its structure; , it can also accelerate the oxidation of other B vitamins . In this study, riboflavin concentrations in the samples decreased by 58.43, 61.53, 64.08, 65.96, and 66.45% at UV doses at 20, 40, 80, 120, and 150 mJ·cm –2 , respectively.…”

Effect of germicidal short wave-length ultraviolet light on the polyphenols, vitamins, and microbial inactivation in highly opaque apple juice

“…Pyridoxamine (B6), pyridoxal (B6), pyridoxine (B6), chlorogenic acid, riboflavin (B2), Epicatechin, Thiamine (B1), Choline (B7). Riboflavin (Min et al, 2002a; Min et al, 2002b), Thiamine (Whitfield et al, 2018), and Pyridoxine (Kawada et al, 2000) are all very photosensitive vitamins and act as photosensitizers due to the presence of the double bonds located within their structures, while also accelerating the oxidation of other B vitamins (De Arrivetti et al, 2013). Riboflavin is a vitamin that is very photosensitive with the capability to act as a photosensitizer because of the double bonds housed within its structure, (Min et al, 2002; Min and Boff, 2002).…”

“…Riboflavin is a vitamin that is very photosensitive with the capability to act as a photosensitizer because of the double bonds housed within its structure, (Min et al, 2002; Min and Boff, 2002). it can accelerate the oxidation of other B vitamins (De O.R. Arrivetti et al, 2013).…”

Photodynamic Efficiency: From Molecular Photochemistry to Cell Death

“…In biological conditions, vitamins and reduced coenzymes can act as initial electron donors to the triplet excited state. Riboflavin triplet excited state, for example, is known to react with folate and pyridoxal phosphate [ 24 , 25 ]. However, their oxidized products can be stable and not always induce a radical chain reaction.…”