Chemical quenching of singlet oxygen by betanin.
Betanin is the best known natural dye belonging to the betacyanin family. In this work, efficient singlet oxygen quenching by betanin in deuterated water with the rate constant 1.20 ± 0.15 × 10(8) M(-1) s(-1) is reported, deduced from the (1)O2 phosphorescence decays measured as a function of betanin concentration. The quenching occurs by a chemical mechanism, as confirmed by the analysis of the transient absorption kinetics at the probe λ ∼ 535 nm, by comparison of the initial triplet signal amplitude of perinaphthenone acting as the (1)O2 photosensitizer with the final bleaching signal of betanin. The main betanin oxidation product is 2-decarboxy-2,3-dehydrobetanin, with its formation observed as the transient absorption signal at λ ∼ 445 nm. LC-MS/MS analysis of the photolyzed solutions supports the product identification as 2-decarboxy-2,3-dehydrobetanin, based on the molecular ion [M](+) observed at m/z 505. Isobetanin also undergoes a similar photooxidation reaction.
Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University in Poznan, Umultowska 85, 61-614 Poznan, Poland. gotardb@amu.edu.pl.
Monika
M
Wendel
Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University in Poznan, Umultowska 85, 61-614 Poznan, Poland. gotardb@amu.edu.pl.
Stanislaw
S
Nizinski
Faculty of Chemistry, Adam Mickiewicz University in Poznan, Umultowska 89b, 61-614 Poznan, Poland.
Mateusz
M
Gierszewski
Faculty of Chemistry, Adam Mickiewicz University in Poznan, Umultowska 89b, 61-614 Poznan, Poland.
Dorota
D
Prukala
Faculty of Chemistry, Adam Mickiewicz University in Poznan, Umultowska 89b, 61-614 Poznan, Poland.
Marek
M
Sikorski
Department of Analytical Chemistry, Faculty of Chemical Engineering and Technology, Institute C-1, Cracow University of Technology, Warszawska 24, 31-155 Cracow, Poland.
Karolina
K
Starzak
Department of Analytical Chemistry, Faculty of Chemical Engineering and Technology, Institute C-1, Cracow University of Technology, Warszawska 24, 31-155 Cracow, Poland.
Slawomir
S
Wybraniec
Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University in Poznan, Umultowska 85, 61-614 Poznan, Poland. gotardb@amu.edu.pl.
Gotard
G
Burdzinski
D050859:Betacyanins / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D010084:Oxidation-Reduction; D010782:Photolysis / Q000528:radiation effects; D026082:Singlet Oxygen / Q000737:chemistry*; D053719:Tandem Mass Spectrometry; D014466:Ultraviolet Rays
D050859:Betacyanins; D026082:Singlet Oxygen; C020228:betanin