Instituto de Tecnología Química UPV-CSIC, Universidad Politécnica de Valencia, Consejo Superior de Investigación Cientificas, Valencia, Spain.
Photochem Photobiol Sci. 2011 Sep;10(9):1474-9. doi: 10.1039/c1pp05072a. Epub 2011 May 5.
In the present work, three dibenzoylmethane derivatives in their β-diketo form have been selected to investigate their photophysical and photochemical behavior upon interaction with human serum albumin (HSA). In organic solvents, absorption and phosphorescence emission spectra of the α-bromo derivative of avobenzone (BrAB) were similar to those of the α-methylated and α-propyl analogs (MeAB and PrAB). However, laser flash photolysis experiments revealed a different transient species centered at 350 nm, assigned to the radical obtained from a singlet excited state dehalogenation process. Interestingly, the transient absorption spectrum of BrAB within HSA showed the typical features of the β-diketone triplet excited state. In the case of MeAB and PrAB derivatives, binding to HSA was associated with a significant increase of their triplet lifetimes as compared to acetonitrile. Finally, the Norrish type II process has been considered as a model to evaluate the influence of the protein microenvironment on the photoreactivity. In this context, photodegradation of PrAB in aerated solutions, to give avobenzone (AB), has been monitored by UV spectroscopy. Interestingly, the quantum yields of AB formation were markedly dependent on the reaction medium (1.4 × 10(-2) in acetonitrile and 3.9 × 10(-2) within albumin medium); by contrast, chemical yields of ca. 50% were obtained in both cases.
在本工作中，选择了三种二苯甲酰甲烷衍生物的β-二酮形式，以研究它们与人体血清白蛋白（HSA）相互作用时的光物理和光化学行为。在有机溶剂中，阿伏苯宗（Avobenzone）的α-溴代衍生物（BrAB）的吸收和磷光发射光谱与α-甲基化和α-丙基类似物（MeAB 和 PrAB）相似。然而，激光闪光光解实验揭示了一个不同的瞬态物种，其中心位于 350nm，归因于从单重激发态脱卤过程中获得的自由基。有趣的是，BrAB 在 HSA 内的瞬态吸收光谱显示了β-二酮三重激发态的典型特征。对于 MeAB 和 PrAB 衍生物，与 HSA 结合会导致其三重态寿命与乙腈相比显著增加。最后，考虑了 Norrish 型 II 过程作为评估蛋白质微环境对光反应性影响的模型。在这种情况下，通过紫外光谱监测了 PrAB 在有氧溶液中发生 Norrish 型 II 反应生成阿伏苯宗（Avobenzone）的光降解。有趣的是，AB 形成的量子产率明显取决于反应介质（在乙腈中为 1.4×10(-2)，在白蛋白介质中为 3.9×10(-2)）；相比之下，两种情况下的化学产率约为 50%。
