Fröbel Sascha, Levi Lucilla, Ulamec Sabine M, Gilch Peter
Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225, Düsseldorf, Germany.
Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225, Düsseldorf, Germany.
Chemphyschem. 2016 May 4;17(9):1377-86. doi: 10.1002/cphc.201500889. Epub 2015 Nov 26.
Psoralens are heterocyclic compounds which are, among other uses, used to treat skin deseases in the framework of PUVA therapy. In the dark, they intercalate into DNA and can form photoadducts with thymines upon UV-A excitation, which harms the affected cells. We have recently discovered that after excitation of intercalated psoralens, an efficient photoinduced electron transfer (PET) from DNA occurs. Here, the PET is studied in detail by means of femtosecond transient absorption spectroscopy. Using DNA samples that contain either only GC or AT base pairs, we show that only guanine donates the electrons. Additionally, the substituent effects on PET are studied relying on three different psoralen derivatives. The substitution alters spectroscopic and electrochemical properties of the psoralens, which are determined by cyclic voltammetry and steady state spectroscopy. These experiments allow us to estimate the PET energetics, which are in line with the measured kinetics. Implications for the applications of psoralens are discussed.
补骨脂素是杂环化合物，在多种用途中，它被用于光化学疗法（PUVA）治疗皮肤病。在黑暗中，它们嵌入DNA，并在紫外线A激发下与胸腺嘧啶形成光加合物，从而损害受影响的细胞。我们最近发现，嵌入的补骨脂素被激发后，DNA会发生高效的光致电子转移（PET）。在此，通过飞秒瞬态吸收光谱对光致电子转移进行了详细研究。使用仅包含GC或AT碱基对的DNA样本，我们发现只有鸟嘌呤会提供电子。此外，还依靠三种不同的补骨脂素衍生物研究了取代基对光致电子转移的影响。取代作用改变了补骨脂素的光谱和电化学性质，这些性质通过循环伏安法和稳态光谱法测定。这些实验使我们能够估算光致电子转移的能量学，其与测得的动力学一致。文中还讨论了补骨脂素应用的相关影响。
