Center for Developmental Therapeutics, Seattle Children's Research Institute, Division of Gastroenterology and Hepatology, Department of Pediatrics, University of Washington, Seattle, Washington 98101, USA.
Chem Res Toxicol. 2011 Dec 19;24(12):2142-52. doi: 10.1021/tx200290s. Epub 2011 Nov 11.
Tetrandrine, a bisbenzylisoquinoline alkaloid, has demonstrated promising pharmacologic activities. The alkaloid has a great potential for clinical use, so a careful, thorough toxicity evaluation of the alkaloid is required. In the present study, 24 h acute toxicity of tetrandrine was evaluated in CD-1 mice. Single intraperitoneal doses of tetrandrine at 150 mg (0.24 mmol)/kg were found to cause alveolar hemorrhage and over 3-fold elevation of lactate dehydrogenase activity in bronchoalveolar lavage fluids. Ethidium-based staining showed loss of membrane integrity in significant numbers of cells in the lungs of the animals treated with the same doses of tetrandrine. As much as 60% reduction in cell viability was observed after 24 h of exposure to tetrandrine at 40 μM in human lung cell lines NL-20 and WI-38. Ketoconazole, an inhibitor of P450 3A, showed a protective effect on the pulmonary injury in mice given tetrandrine. A glutathione (GSH) conjugate derived from O-demethylated tetrandrine was detected in incubations of tetrandrine with NADPH- and GSH-supplemented human liver and mouse lung microsomes. The electrophilic metabolite trapped by GSH is considered to be a quinone methide derivative. The formation of the metabolite reactive to GSH was found to require the presence of NADPH. The coincubation of ketoconazole suppressed the generation of the GSH conjugate. Tetrandrine was incubated with a selection of recombinant human cytochrome P450 enzymes, and only P450s 3A4 and 3A5 were responsible for the production of the reactive metabolite. The results implicate a possible correlation between the formation of the quinone methide metabolite of tetrandrine and the pulmonary toxicity induced by tetrandrine.
汉防己甲素是一种双苄基异喹啉生物碱，具有广泛的药理活性。该生物碱具有很大的临床应用潜力，因此需要对其进行仔细、全面的毒性评估。在本研究中，采用 CD-1 小鼠评价汉防己甲素的 24 小时急性毒性。腹腔内给予 150mg（0.24mmol/kg）的汉防己甲素单剂量，导致肺泡出血和支气管肺泡灌洗液中乳酸脱氢酶活性升高 3 倍以上。基于溴化乙锭的染色显示，用相同剂量的汉防己甲素处理的动物肺部有大量细胞的膜完整性丧失。在人肺细胞系 NL-20 和 WI-38 中，汉防己甲素在 40μM 下暴露 24 小时后，细胞活力降低了 60%。汉防己甲素抑制剂酮康唑对给予汉防己甲素的小鼠的肺部损伤表现出保护作用。在含有 NADPH 和 GSH 的人肝和鼠肺微粒体孵育物中检测到汉防己甲素的 O-去甲基化产物与 GSH 的轭合物。与 GSH 结合的亲电代谢物被认为是一种醌甲亚胺衍生物。发现 GSH 反应代谢物的形成需要 NADPH 的存在。酮康唑的共孵育抑制了 GSH 轭合物的生成。汉防己甲素与一系列重组人细胞色素 P450 酶孵育，只有 P450s 3A4 和 3A5 负责产生反应性代谢物。结果表明，汉防己甲素的醌甲亚胺代谢物的形成与汉防己甲素引起的肺部毒性之间可能存在相关性。
