Colon cancer affects 1.23 million people worldwide and is the third most common malignant disease in men and the second in women. The only curative treatment is surgical resection, but a significant number of patients develop local recurrence or distant metastases. One of the alternative treatment methods for colon cancer is photodynamic therapy (PDT). In recent years, hypericin (HYP) derived from Hypericum perforatum has been suggested as a strong candidate photosensitizer for PDT. Our interest is focused on the biophysical changes in colon cancer cells in relation to HYP-mediated PDT. In this study, HYP-mediated PDT at 0.04, 0.08 or 0.15 μM HYP concentrations was performed in HT-29 colon adenocarcinoma cells and the Electron Paramagnetic Resonance (EPR) spectra of the spin labeled cells were obtained. Plasma membranes are already heterogeneous structures; the presence of cancer cells increased the heterogeneity and also fluidity of the plasma membranes. Therefore, the obtained spectra were evaluated by EPRSIMC program, which provides the calculation of heterogeneous structures up to four spectral components with different fluidity characteristics. Generally, two motional patterns were obtained from calculations and the number of them increased at the highest concentration. As the order parameters of the most populated components compared, an increase was observed depending on the HYP concentration. However, because of the heterogeneous structure of membrane, the order parameters of the less populated components did not exhibit a regular distribution. After HYP-mediated PDT, concentration dependent changes were observed in the domain parameters indicating an increase in the HYP accumulation.

中文翻译：

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金丝桃素介导的光动力治疗后HT-29结肠腺癌细胞中的电子顺磁共振（EPR）自旋标记研究

结肠癌在全球范围内影响着123万人，是男性中第三大最常见的恶性疾病，在女性中第二大。唯一的治疗方法是手术切除，但大量患者出现局部复发或远处转移。结肠癌的替代治疗方法之一是光动力疗法（PDT）。近年来，有人认为源自贯叶连翘的金丝桃素（HYP）是PDT的强候选光敏剂。我们的兴趣集中在与HYP介导的PDT相关的结肠癌细胞的生物物理变化上。在这项研究中，在HT-29结肠腺癌细胞中以0.04、0.08或0.15μMHYP浓度进行HYP介导的PDT，并获得了自旋标记细胞的电子顺磁共振（EPR）光谱。质膜已经是异质结构。癌细胞的存在增加了质膜的异质性和流动性。因此，通过EPRSIMC程序对获得的光谱进行了评估，该程序可提供多达四个具有不同流动性特征的光谱分量的非均质结构的计算。通常，从计算中获得了两种运动模式，并且在最高浓度下它们的数量增加了。由于比较了人口最多的组分的订购参数，因此观察到的升高取决于HYP浓度。但是，由于膜的异质结构，人口较少的组件的顺序参数未显示规则分布。在HYP介导的PDT之后，