Kinski Elisa, Marzenell Paul, Hofer Walter, Hagen Helen, Raskatov Jevgenij A, Knaup Karl X, Zolnhofer Eva M, Meyer Karsten, Mokhir Andriy
Friedrich-Alexander-University of Erlangen-Nürnberg, Department of Chemistry and Pharmacy, Organic Chemistry II, Henkestr. 42, 91054 Erlangen, Germany.
Ruprecht-Karls-University of Heidelberg, Institute of Inorganic Chemistry, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
J Inorg Biochem. 2016 Jul;160:218-24. doi: 10.1016/j.jinorgbio.2016.02.023. Epub 2016 Mar 2.
Aminoferrocene-based prodrugs are activated in the presence of cancer-specific amounts of reactive oxygen species, e.g. H2O2, with the formation of products of two types: Fe-containing complexes, which catalyze generation of HO and O2(-), and quinone methides, which alkylate glutathione and inhibit the antioxidative system of the cell. Both processes act synergistically by increasing the oxidative stress in cancer cells thereby leading to their death. However, in the activation step including the cleavage of a B-C bond one molecule of H2O2 is consumed that counteracts the desired effect of the products released from aminoferrocenes. We replaced an H2O2-sensitive trigger in original prodrugs with an azide group. This trigger is slowly reduced in the presence of glutathione with the formation of an unstable arylamine intermediate, which decomposes with the release of iron ions and iminoquinone methides. These products induce strong oxidative stress in cells as we confirmed using 2',7'-dichlorodihydrofluorescin diacetate reagent in combination with flow cytometry. In this case the activation process does not consume H2O2. Correspondingly, we observed that the azide-containing prodrug is substantially more toxic towards human promyelocytic leukemia cell line HL-60 (IC50=27±4μM) than its H2O2-responsive analogue (IC50>50μM).
基于氨基二茂铁的前药在癌症特异性量的活性氧（如H2O2）存在下被激活，形成两种类型的产物：含铁配合物，其催化HO和O2(-)的生成；以及醌甲基化物，其使谷胱甘肽烷基化并抑制细胞的抗氧化系统。这两个过程通过增加癌细胞中的氧化应激协同作用，从而导致癌细胞死亡。然而，在包括B-C键断裂的激活步骤中，会消耗一分子H2O2，这抵消了氨基二茂铁释放的产物的预期效果。我们用叠氮基团取代了原始前药中对H2O2敏感的触发基团。该触发基团在谷胱甘肽存在下缓慢还原，形成不稳定的芳胺中间体，该中间体分解并释放出铁离子和亚氨基醌甲基化物。正如我们使用2',7'-二氯二氢荧光素二乙酸试剂结合流式细胞术所证实的那样，这些产物在细胞中诱导强烈的氧化应激。在这种情况下，激活过程不消耗H2O2。相应地，我们观察到含叠氮基的前药对人早幼粒细胞白血病细胞系HL-60（IC50=27±4μM）的毒性比其对H2O2响应的类似物（IC50>50μM）大得多。
