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Photooxidation of Pterin in Aqueous Solutions: Biological and Biomedical Implications
Author(s) -
Cabrerizo Franco M.,
Dántola María L.,
Thomas Andrés H.,
Lorente Carolina,
Braun André M.,
Oliveros Esther,
Capparelli Alberto L.
Publication year - 2004
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.200490135
Subject(s) - pterin , chemistry , aqueous solution , singlet oxygen , reactivity (psychology) , high performance liquid chromatography , spectrophotometry , photochemistry , reaction rate constant , thin layer chromatography , chromatography , oxygen , organic chemistry , enzyme , kinetics , cofactor , medicine , physics , alternative medicine , pathology , quantum mechanics
Studies of the photochemical reactivity of pterin (=2‐aminopteridin‐4(3 H )‐one; PT) in acidic (pH 5.0–6.0) and alkaline (pH 10.2–10.8) aqueous solutions have been performed. The photochemical reactions were followed by UV/VIS spectrophotometry, thin layer chromatography (TLC), high‐performance liquid chromatography (HPLC), and an enzymatic method for H 2 O 2 determination. PT is not light‐sensitive in the absence of molecular oxygen, but it undergoes photooxidation in the presence of O 2 , yielding several nonpteridinic products. The quantum yields for PT disappearance were found to be 8.2 (±0.6)×10 −4 and 1.2 (±0.2)×10 −3 in acidic and alkaline media, respectively. H 2 O 2 was detected and quantified in irradiated solutions of PT; and its importance from a biomedical point of view is discussed. The rate constant of the chemical reaction between singlet oxygen ( 1 O 2 ) and PT was determined to be 2.5 (±0.2)×10 5 l mol −1 s −1 in alkaline medium, and the role of 1 O 2 in the photooxidation of pterin was evaluated.