Gasparro F P, Gattolin P, Olack G A, Deckelbaum L I, Sumpio B E
Department of Dermatology, Yale University School of Medicine, New Haven, CT 06510.
Photochem Photobiol. 1993 Jun;57(6):1007-10. doi: 10.1111/j.1751-1097.1993.tb02963.x.
The formation of 8-methoxypsoralen-DNA monoadducts and cross-links is presumed to be responsible for the efficacy of photochemotherapies that employ 8-methoxypsoralen activated with long-wavelength ultraviolet radiation (UVA, 320-400 nm). In this report it is shown that 8-methoxypsoralen can also be activated with visible light (419 nm). Bovine aorta smooth muscle cells were treated with 8-methoxypsoralen (1,000 ng/mL) and 419 nm light (up to 12 J/cm2). Cellular DNA was isolated, hydrolyzed using nucleolytic enzymes and then analyzed by reversed-phase high-performance liquid chromatography. The primary effect of using visible light instead of long-wavelength ultraviolet radiation is a more than 10-fold reduction in the extent of cross-link formation. Because the extent of monoadduct and cross-link formation has not been routinely measured in experiments in which cellular assays have been performed, it is difficult to correlate cell response to the presence of a particular type of 8-methoxypsoralen photoadduct (monoadduct or cross-link). Thus, the use of visible light allows the study of cells containing nearly 100% monoadducts. In addition, the reduction in cross-link formation when visible light is used to activate the compound may also reduce the mutagenicity of 8-methoxypsoralen and hence enhance its therapeutic efficacy.
8-甲氧基补骨脂素-DNA单加合物和交联物的形成被认为是采用长波长紫外线（UVA，320 - 400nm）激活的8-甲氧基补骨脂素光化学疗法产生疗效的原因。在本报告中表明，8-甲氧基补骨脂素也可用可见光（419nm）激活。用8-甲氧基补骨脂素（1000ng/mL）和419nm光（高达12J/cm²）处理牛主动脉平滑肌细胞。分离细胞DNA，用核酸酶水解，然后通过反相高效液相色谱分析。使用可见光而非长波长紫外线的主要影响是交联物形成程度降低了10倍以上。由于在进行细胞分析的实验中尚未常规测量单加合物和交联物的形成程度，因此难以将细胞反应与特定类型的8-甲氧基补骨脂素光加合物（单加合物或交联物）的存在相关联起来。因此，使用可见光可以研究几乎含有100%单加合物的细胞。此外，当使用可见光激活该化合物时交联物形成的减少也可能降低8-甲氧基补骨脂素的致突变性，从而提高其治疗效果。
