In the present study, protohypericin was synthesised in order to compare its intrinsic photocytotoxicity with that of hypericin. The experimental work was performed in specific filtered light conditions that prevented both an unintended photoconversion of protohypericin and photosensitization of the cells. Assessing the photocytotoxicity as a function of irradiation time, it was found that the photocytotoxicity of both compounds converged after a long irradiation time (i.e., 15 min), while the difference between the photocytotoxicities was maximal after a short irradiation time (i.e., 1 min). Since this could not be accounted for by a redistribution of protohypericin during irradiation, and the different irradiation times corresponded to different degrees of photoconversion of protohypericin into hypericin, the results clearly suggest that protohypericin exhibits intrinsically a dramatically lower photoactivity as compared to hypericin.
本研究合成了原
金丝桃素,以比较其与
金丝桃素的内在光细胞毒性。实验工作是在特定的滤光条件下进行的,以防止原
金丝桃素发生意外光转化和细胞光敏化。在评估光细胞毒性与辐照时间的函数关系时发现,两种化合物的光细胞毒性在较长的辐照时间(即 15 分钟)后趋于一致,而在较短的辐照时间(即 1 分钟)后,光细胞毒性之间的差异达到最大。由于这不是原
金丝桃素在辐照过程中重新分布造成的,而且不同的辐照时间与原
金丝桃素光
化学转化为
金丝桃素的程度不同相对应,因此结果清楚地表明,与
金丝桃素相比,原
金丝桃素本质上具有更低的光活性。