Cabrerizo Franco M, Dántola M Laura, Petroselli Gabriela, Capparelli Alberto L, Thomas Andrés H, Braun André M, Lorente Carolina, Oliveros Esther
Departamento de Química, Facultad de Ciencias Exactas, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata, CONICET, La Plata, Argentina.
Photochem Photobiol. 2007 May-Jun;83(3):526-34. doi: 10.1562/2006-09-15-RA-1041.
Pterins (PTs) belong to a class of heterocyclic compounds present in a wide range of living systems. They participate in relevant biological functions and are involved in different photobiological processes. We have investigated the reactivity of conjugated PTs (folic acid [FA], 10-methylfolic acid [MFA], pteroic acid [PA]) and unconjugated PTs (PT, 6-hydroxymethylpterin [HPT], 6-methylpterin [MPT], 6,7-dimethylpterin [DPT], rhamnopterin [RPT]) with singlet oxygen (1O2) in aqueous solutions, and compared the efficiencies of chemical reaction and physical quenching. The chemical reactions between 1O2, produced by photosensitization, and PT derivatives were followed by UV-visible spectrophotometry and high-performance liquid chromatography, and corresponding rate constants (k(r)) were evaluated. Whenever possible, products were identified and quantified. Rate constants of 1O2 total quenching by the PT derivatives investigated were obtained from steady-state 1O2 luminescence measurements. Results show that the behavior of conjugated PTs differs considerably from that of unconjugated derivatives, and the mechanisms of 1O2 physical quenching by these compounds and of their chemical reaction with 1O2 are discussed in relation to their structural features.
蝶呤（PTs）属于一类存在于广泛生命系统中的杂环化合物。它们参与相关生物功能，并涉及不同的光生物学过程。我们研究了共轭蝶呤（叶酸[FA]、10-甲基叶酸[MFA]、蝶酸[PA]）和非共轭蝶呤（蝶呤[PT]、6-羟甲基蝶呤[HPT]、6-甲基蝶呤[MPT]、6,7-二甲基蝶呤[DPT]、鼠李蝶呤[RPT]）在水溶液中与单线态氧（1O2）的反应性，并比较了化学反应和物理猝灭的效率。通过紫外-可见分光光度法和高效液相色谱法跟踪光敏化产生的1O2与PT衍生物之间的化学反应，并评估相应的速率常数（k(r)）。只要有可能，就对产物进行鉴定和定量。通过稳态1O2发光测量获得所研究的PT衍生物对1O2的总猝灭速率常数。结果表明，共轭蝶呤的行为与非共轭衍生物有很大不同，并根据这些化合物的结构特征讨论了它们对1O2的物理猝灭机制及其与1O2的化学反应机制。
