Jelk Jennifer, Balmer Vreni, Stibal David, Giannini Federico, Süss-Fink Georg, Bütikofer Peter, Furrer Julien, Hemphill Andrew
Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland.
Institute of Parasitology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, CH-3012 Berne, Switzerland.
Exp Parasitol. 2019 Oct;205:107753. doi: 10.1016/j.exppara.2019.107753. Epub 2019 Aug 27.
Trypanosoma brucei causes human African trypanosomiasis and Nagana disease in cattle, imposing substantial medical and economic burden in sub-Saharan Africa. The current treatments have limitations, including the requirement for elaborated protocols, development of drug resistance, and they are prone to adverse side effects. In vitro screening of a library of 14 dinuclear-thiolato bridged arene ruthenium complexes, originally developed for treatment of cancer cells, resulted in the identification of 7 compounds with IC values ranging from 3 to 26 nM. Complex [(η-p-MeCHPr)Ru(μ-SCH-o-Pr)]Cl (2) (IC = 4 nM) and complex [(η-p-MeCHPr)Ru(μ-SCHCH-p-Bu)(μ-SCH-p-OH)]BF(9) (IC = 26 nM) were chosen for further assessments. Application of complex 2 and 9 at 20 nM and 200 nM, respectively, for 4.5 h induced alterations in the trypanosome mitochondrion as evidenced by immunofluorescence employing an antibody against mitochondrial Hsp70 and Mitotracker labeling. Transmission electron microscopy of parasites taken at 2 and 4h of treatment demonstrated massive alterations in the mitochondrial ultrastructure, while other organelles and structural elements of the parasites remained unaffected. Complex 2 treated trypanosomes exhibited a distorted mitochondrial membrane, and the mitochondrial matrix was transformed into an amorphous mass with different degrees of electron densities. Complex 9 did not notably impair the integrity of the membrane, but the interior of the mitochondrion appeared either completely translucent, or was filled with filamentous structures of unknown nature. Dose- and time-dependent effects of these two compounds on the mitochondrial membrane potential were detected by tetramethylrhodamine ethyl ester assay. Thus, the mitochondrion and associated metabolic processes are an important target of dinuclear thiolato-bridged arene ruthenium complexes in T. brucei.
布氏锥虫可引发人类非洲锥虫病以及牛的那加那病，给撒哈拉以南非洲地区带来了巨大的医学和经济负担。当前的治疗方法存在局限性，包括需要复杂的治疗方案、会产生耐药性，而且容易出现副作用。对最初为治疗癌细胞而研发的14种双核硫醇桥联芳烃钌配合物文库进行体外筛选，结果鉴定出7种化合物，其半数抑制浓度（IC）值在3至26 nM之间。选择配合物[(η-p-MeCHPr)Ru(μ-SCH-o-Pr)]Cl (2)（IC = 4 nM）和配合物[(η-p-MeCHPr)Ru(μ-SCHCH-p-Bu)(μ-SCH-p-OH)]BF(9)（IC = 26 nM）进行进一步评估。分别以20 nM和200 nM的浓度应用配合物2和9，处理4.5小时后，锥虫线粒体出现改变，这通过使用抗线粒体热休克蛋白70抗体进行免疫荧光和Mitotracker标记得以证实。在处理2小时和4小时时对寄生虫进行透射电子显微镜观察，结果显示线粒体超微结构发生了大量改变，而寄生虫的其他细胞器和结构元件未受影响。经配合物2处理的锥虫线粒体膜出现扭曲，线粒体基质转变为具有不同电子密度的无定形物质。配合物9并未显著损害膜的完整性，但线粒体内部要么完全半透明，要么充满了性质未知的丝状结构。通过四甲基罗丹明乙酯检测法检测了这两种化合物对线粒体膜电位的剂量和时间依赖性影响。因此，线粒体及相关代谢过程是双核硫醇桥联芳烃钌配合物在布氏锥虫中的重要作用靶点。
