基于单线态氧发光检测的EGCG抗光敏氧化效应研究

Epigallocatechi gallate (EGCG) is the major component of polyphenols in green tea. It is known that EGCG have an exceptional antioxidant capacity, and which is not only quenching the singlet oxygen (1O2), but also inhibit the generation of excited state of photosensitizer. This study the time-resolved singlet oxygen luminescence detection system which combined with fluorescence and oxygen monitor function will be used to study the quenching reaction of single state and triplet state of photosensitizer and 1O2 by EGCG. Meanwhile, the relationship of EGCG concentration and the 1O2 luminescence intensity will be quantitatively evaluated by using high sensitivity 1O2 imaging system for animal skin model and skin window chamber. This project aiming at exploring the influence of EGCG concentration, photosensitizer and its concentration, irradiation wavelength and intensity, molecular oxygen and issue optical properties on the effect of EGCG anti-photosensitized oxidation, which can help people have a thorough understanding the photo-physical mechanism of the anti-photosensitized oxidation effect of EGCG and useful for the application of EGCG in anti-photosensitized oxidation and the research on the other component of polyphenols in green tea.

表没食子儿茶素没食子酸酯（Epigallocatechin gallate, EGCG）是茶多酚的主要组分之一，具有较强的抗氧化性，能够有效淬灭单线态氧（Singlet Oxygen, 1O2）并且抑制光敏物质激发态产物的生成。本项目利用具有荧光和氧含量监测功能的时间分辨1O2发光检测系统测量并计算得到光敏化过程中EGCG对光敏物质激发单重态、激发三重态和1O2的淬灭速率。与此同时，利用高灵敏度的空间分辨1O2发光成像系统，定量评估动物光敏化皮肤和血管皮窗模型中EGCG浓度与1O2发光强度之间关系。通过实验研究阐明EGCG浓度、光敏剂类型、光敏剂浓度、辐照光波长、光剂量、氧含量和组织体光学特性等对EGCG抗光敏氧化作用的定量影响。本研究有助于人们深入了解EGCG抗光敏氧化的光物理作用机制，为EGCG在抗光敏化氧化领域的应用以及其它儿茶素单体组分的抗氧化研究奠定坚实的理论基础。

生物体内的活性氧（Reactive oxygen species，ROS）过量引起氧化应激将导致脂质、DNA和蛋白质氧化损伤，从而引发一系列生理和病理反应。绿茶中茶多酚的主要成分表没食子儿茶素没食子酸酯（(-)-Epigallocatechin-3-gallate，EGCG）具有强抗氧化性，能有效抑制ROS。单线态氧（Singlet Oxygen, 1O2）是光敏化过程的主要活性氧产物。本项目主要开展了EGCG对光敏化单线态氧淬灭效应研究，首先利用门控型光电倍增管构建了高灵敏度的时间分辨单线态氧发光检测系统，优化门控型时间分辨单线态氧发光检测系统的触发时间和阈值电压；其次，测量EGCG与不同光敏剂及混合溶液的吸收光光谱，荧光光谱，激发三重态吸收光谱和时间分辨单线态氧发光光谱，计算获得EGCG对光敏化单线态氧和光敏剂激发三重态的淬灭速率；然后，在模拟不同蛋白质含量的人体液环境中，当EGCG小于200 μM时，EGCG对光敏化单线态氧具有显著的淬灭效应；在组织模拟液中，当毛细血管模型管径大于0.3mm时，毛细管对单线态氧发光成像贡献的有效体积比低于50%。；最后，在相同治疗条件下，HMME实验组的动血管完全封闭，HMME与EGCG实验组的动脉血管并未发生封闭现象，散斑血流图中的动脉血流清晰可见，在HMME治疗组鼠背皮窗有较强的单线态氧发光信号，HMME+EGCG治疗组鼠背皮窗中未见到明显的单线态氧发光信号，初步试验表明EGCG对HMME有较好的单线态氧淬灭效果。