Photooxidation of pterin in aqueous solutions: Biological and biomedical implications
Studies of the photochemical reactivity of pterin (-2-aminopteridin-4(3H)- 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 li...
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| Autores principales: | , , , , , , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_16121872_v1_n11_p1800_Cabrerizo |
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| Sumario: | Studies of the photochemical reactivity of pterin (-2-aminopteridin-4(3H)- 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 H2O2 determination. PT is not light-sensitive in the absence of molecular oxygen, but it undergoes photooxidation in the presence of O2 , 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. H2O2 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 (1O2) and PT was determined to be 2.5 (-0.2)-105 l mol-1 s-1 in alkaline medium, and the role of 1O2 in the photooxidation of pterin was evaluated. © 2004 Verlag Helvetica Chimica Acta AG, Zürich. |
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