Cabrerizo Franco M, Dántola María L, Thomas Andrés H, Lorente Carolina, Braun André M, Oliveros Esther, Capparelli Alberto L
Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CONICET, CIC Casilla de Correo 16, Sucursal 4, 1900-La Plata, Argentina.
Chem Biodivers. 2004 Nov;1(11):1800-11. doi: 10.1002/cbdv.200490135.
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) x 10(-4) and 1.2 (+/-0.2) x 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 ((1)O2) and PT was determined to be 2.5 (+/-0.2) x 10(5) l mol(-1) s(-1) in alkaline medium, and the role of (1)O2 in the photooxidation of pterin was evaluated.
已对蝶呤（=2-氨基蝶啶-4(3H)-酮；PT）在酸性（pH 5.0 - 6.0）和碱性（pH 10.2 - 10.8）水溶液中的光化学反应进行了研究。通过紫外/可见分光光度法、薄层色谱法（TLC）、高效液相色谱法（HPLC）以及一种用于测定H2O2的酶法对光化学反应进行了跟踪。在没有分子氧的情况下，PT对光不敏感，但在有O2存在时会发生光氧化反应，生成几种非蝶啶类产物。发现在酸性和碱性介质中PT消失的量子产率分别为8.2（±0.6）×10^(-4) 和1.2（±0.2）×10^(-3)。在PT的辐照溶液中检测并定量了H2O2；并从生物医学角度讨论了其重要性。在碱性介质中，单线态氧((1)O2)与PT之间化学反应的速率常数测定为2.5（±0.2）×10^5 l mol^(-1) s^(-1)，并评估了(1)O2在蝶呤光氧化反应中的作用。
