Grünig David, Felser Andrea, Bouitbir Jamal, Krähenbühl Stephan
Division of Clinical Pharmacology & Toxicology, University Hospital Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland.
Division of Clinical Pharmacology & Toxicology, University Hospital Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland; Swiss Center of Applied Human Toxicology (SCAHT), Switzerland.
Toxicol In Vitro. 2017 Aug;42:337-347. doi: 10.1016/j.tiv.2017.05.013. Epub 2017 May 16.
The catechol-O-methyltransferase inhibitor tolcapone causes hepatotoxicity and mitochondrial damage in animal models. We studied the interaction of tolcapone with mitochondrial respiration in comparison to entacapone in different experimental models. In HepaRG cells (human cell-line), tolcapone decreased the ATP content (estimated IC 100±15μM) and was cytotoxic (estimated IC 333±45μM), whereas entacapone caused no cytotoxicity and no ATP depletion up to 200μM. Cytochrome P450 induction did not increase the toxicity of the compounds. In HepaRG cells, tolcapone (not entacapone) inhibited maximal complex I- and complex II-linked oxygen consumption. In intact mouse liver mitochondria, tolcapone stimulated state 2 complex II-linked respiration and both compounds inhibited state 3 respiration of complex IV. Mitochondrial uncoupling was confirmed for both compounds by stimulation of complex I-linked respiration in the presence of oligomycin. Inhibition of complex I, II and IV for tolcapone and of complex I and IV for entacapone was directly demonstrated in disrupted mouse liver mitochondria. In HepaRG cells, tolcapone-induced inhibition of mitochondrial respiration was associated with increased lactate and ROS production and hepatocyte necrosis. In conclusion, both compounds uncouple oxidative phosphorylation and inhibit mitochondrial enzyme complexes. Tolcapone is a more potent mitochondrial toxicant than entacapone. Mitochondrial toxicity is a possible mechanism for tolcapone-associated hepatotoxicity.
儿茶酚-O-甲基转移酶抑制剂托卡朋在动物模型中可导致肝毒性和线粒体损伤。我们在不同实验模型中研究了托卡朋与恩他卡朋相比对线粒体呼吸的影响。在HepaRG细胞（人细胞系）中，托卡朋降低了ATP含量（估计IC100±15μM）且具有细胞毒性（估计IC333±45μM），而恩他卡朋在高达200μM时未引起细胞毒性和ATP耗竭。细胞色素P450诱导并未增加这些化合物的毒性。在HepaRG细胞中，托卡朋（而非恩他卡朋）抑制了最大的复合体I和复合体II相关的氧消耗。在完整的小鼠肝脏线粒体中，托卡朋刺激了状态2复合体II相关的呼吸，且两种化合物均抑制了复合体IV的状态3呼吸。通过在寡霉素存在下刺激复合体I相关的呼吸，证实了两种化合物均存在线粒体解偶联。在破碎的小鼠肝脏线粒体中直接证实了托卡朋对复合体I、II和IV以及恩他卡朋对复合体I和IV的抑制作用。在HepaRG细胞中，托卡朋诱导的线粒体呼吸抑制与乳酸和ROS产生增加以及肝细胞坏死相关。总之，两种化合物均使氧化磷酸化解偶联并抑制线粒体酶复合体。托卡朋是比恩他卡朋更强效的线粒体毒物。线粒体毒性是托卡朋相关肝毒性的一种可能机制。
