Wavelength dependent generation of singlet oxygen in the UV region of 280 to 400 nm by endogenous photosensitizers in solutions and skin cells

除了不可否认的阳光的积极作用，紫外线辐射会导致晒伤，皮肤过早老化和皮肤癌。体外研究和评价的潜在损伤机制通常在UVA （320-400 nm）和UVB （280-320 nm）各自的光谱范围内进行分离。UVB辐射被DNA直接吸收，并通过形成环丁烷嘧啶二聚体和嘧啶嘧啶嘧啶光产物对皮肤细胞造成损伤。然而，UVA辐射（340- 400nm）被细胞内的其他分子（内源性光敏剂）吸收，吸收的能量可以转移到分子氧中。这种高活性的单线态氧是暂时形成的，它会导致皮肤细胞的氧化损伤和调节作用。初步结果表明，无论是纯辐射吸收（UVB）还是氧化损伤（UVA）的分离都是不可维持的。此外，UVB辐射可以产生单线态氧，在这里，维生素和脂肪酸作为内源性光敏剂参与其中。UVB辐射在多大程度上在皮肤细胞中产生单线态氧，以及这在细胞损伤机制中起什么作用，目前尚不清楚。此外，内源性光敏剂在UVA或UVB辐照下产生单线态氧的能力发生了显著变化。首先，通过使用发光光谱学，它将被研究，在何种程度上单线态氧可以产生在较短的波长（280-340 nm），尚未检测的内源性光敏剂。此外，还应澄清细胞中已知的损伤机制是否受到影响。其次，研究紫外辐射在辐照过程中对内源性光敏剂的化学修饰程度，以及它们产生单线态氧的效率。因此，光敏剂应单独、依次或并行地用UVA或UVB照射。这些步骤是根据溶液和体外角质形成细胞和成纤维细胞的要求进行的。第三，基质金属蛋白酶、白细胞介素和MAP激酶的调控与不同辐照条件下单线态氧的生成有关。在完成这些步骤后，应该澄清在整个紫外光谱中单线态氧的产生是否以及在多大程度上导致细胞损伤。此外，在UVA和UVB（如阳光）的平行照射下，以及内源性光敏剂在照射过程中的光化学变化，单线态氧在细胞损伤模式中的作用应该在多大程度上得到重新评估。

In addition to the undeniably positive effects of sunlight, the contained ultraviolet radiation can cause sunburn, premature skin aging and skin cancer. The underlying damage mechanisms investigated and evaluated in vitro are generally separated in the respective spectral areas UVA (320-400 nm) and UVB (280-320 nm). The UVB radiation is absorbed directly by DNA and causes damage to the skin cells by the formation of cyclobutane pyrimidine dimers and pyrimidine pyrimidone photoproducts. UVA radiation (340-400 nm), however, is absorbed by other molecules (endogenous photosensitizers) in the cells, where the absorbed energy can be transferred to molecular oxygen. This highly reactive singlet oxygen is formed temporarily, which causes oxidative damage as well as regulatory effects in the skin cells.Preliminary results have shown that the separation in either pure radiation absorption (UVB) or oxidative damage (UVA) is so not to maintain. Also UVB radiation can produce singlet oxygen, and here among others vitamins and fatty acids are involved as endogenous photosensitizers. To what extent UVB radiation generates singlet oxygen in skin cells and what role this plays for the cellular damage mechanisms, is currently not known. In addition, it was shown that endogenous photosensitizers irradiated by UVA or UVB radiation change their ability to generate singlet oxygen the significantly.First, by using luminescence spectroscopy, it will be investigated, to what extent singlet oxygen can be created at shorter wavelengths (280-340 nm) by not yet examined endogenous photosensitizers. Also, it shall be clarified whether the known damage mechanisms in cells are affected. Second, it will be investigated to what extent UV radiation chemically modifies the endogenous photosensitizers during irradiation, as well as their efficaccy to generate singlet oxygen. Therefore, the photosensitizers should be irradiated with UVA or UVB individually, sequentially or in parallel. These steps are carried out according to the requirements in solution and on keratinocytes and fibroblasts in vitro. Third, the regulation of Matrix Metallo Proteinases, Interleukins and MAP kinases are correlated with the generation of singlet oxygen under the various irradiation conditions.After performing these steps, it should be clarified whether and to what extent the production of singlet oxygen in the entire UV spectrum contributes to the damage of cells. Further it should be clarified to what extent by parallel irradiation with UVA and UVB (such as sunlight) and the photochemical change of endogenous photosensitizers during irradiation, the role of singlet oxygen is to re-evaluate in the cellular damage patterns.