Yue Jiang, Dong Guicheng, He Chunyan, Chen Jie, Liu Yinghui, Peng Renxiu
Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China.
Toxicology. 2009 Oct 29;264(3):185-91. doi: 10.1016/j.tox.2009.08.006. Epub 2009 Aug 13.
Isoniazid is a widely used drug for the treatment of tuberculosis, but hepatotoxicity is a major concern during treatment. Thiopronin contains an SH-group and is generally considered an antioxidant. The aim of the present study was to investigate the effects of thiopronin during liver injury and DNA damage induced by isoniazid. Rats were injected daily with isoniazid (100 mg/kg, i.p.) for 21 days with or without thiopronin co-administration (60 mg/kg, i.p.) from day 11 to day 21. The influence of thiopronin on isoniazid-induced DNA oxidative damage was analyzed in precision-cut rat liver slices by HPLC-MS/MS. Thiopronin prevented isoniazid-induced hepatotoxicity, indicated by both diagnostic indicators of liver damage (alanine aminotransferase and aspartate aminotransferase) and histopathological analysis. In vivo, thiopronin significantly inhibited isoniazid-induced CYP2E1 activity as assessed by both chlorzoxazone hydroxylase and aniline hydroxylase (p<0.001). Thiopronin concentration-dependently inhibited CYP2E1-dependent aniline hydroxylation, and the Dixon plots suggest that thiopronin is a competitive inhibitor of CYP2E1. Thiopronin markedly attenuated isoniazid-induced inhibition of the detoxification system through cytosolic glutathione S-transferases (GSTs), including mu GST and alpha GST. In precision-cut liver slices, the free radical scavenging activity of thiopronin reduced the generation of DNA adducts induced by isoniazid (p<0.05). Altogether, these results suggest that thiopronin exerts its hepatoprotective activity against isoniazid-induced hepatotoxicity by inhibiting the production of free radicals in addition to its role as a scavenger. Thiopronin may reduce free radical generation via inhibition of hepatic CYP2E1 and increase the removal of free radicals directly or through the induction of cytosolic GSTs.
异烟肼是一种广泛用于治疗结核病的药物，但肝毒性是治疗期间的主要关注点。硫普罗宁含有巯基，通常被认为是一种抗氧化剂。本研究的目的是调查硫普罗宁在异烟肼诱导的肝损伤和DNA损伤过程中的作用。从第11天至第21天，大鼠每天腹腔注射异烟肼（100mg/kg），共21天，部分大鼠同时腹腔注射硫普罗宁（60mg/kg）。通过HPLC-MS/MS分析硫普罗宁对异烟肼诱导的大鼠肝切片DNA氧化损伤的影响。硫普罗宁可预防异烟肼诱导的肝毒性，这通过肝损伤诊断指标（丙氨酸转氨酶和天冬氨酸转氨酶）及组织病理学分析得以证实。在体内，通过氯唑沙宗羟化酶和苯胺羟化酶评估，硫普罗宁显著抑制异烟肼诱导的CYP2E1活性（p<0.001）。硫普罗宁浓度依赖性地抑制CYP₂E₁依赖的苯胺羟化，狄克逊图表明硫普罗宁是CYP2E1的竞争性抑制剂。硫普罗宁显著减轻异烟肼诱导的通过胞质谷胱甘肽S-转移酶（GSTs）包括μGST和αGST的解毒系统抑制。在精密肝切片中，硫普罗宁的自由基清除活性减少了异烟肼诱导的DNA加合物的生成（p<0.05）。总之，这些结果表明，硫普罗宁除了作为清除剂外，还通过抑制自由基的产生发挥其对异烟肼诱导的肝毒性的肝保护活性。硫普罗宁可能通过抑制肝CYP2E1减少自由基生成，并直接或通过诱导胞质GSTs增加自由基的清除。
