Smith S L, Fishwick J, McLean W G, Edwards G, Ward S A
Department of Pharmacology and Therapeutics, University of Liverpool, U.K.
Biochem Pharmacol. 1997 Jan 10;53(1):5-10. doi: 10.1016/s0006-2952(96)00591-6.
The role of haem in the neurotoxicity of artemisinin derivatives has been studied in vitro by examining neurite outgrowth measured by image analysis and cellular metabolism of the tetrazolium salt MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) measured spectrophotometrically in the neuroblastoma cell line NB2a, and by examining binding of radiolabelled dihydroartemisinin to NB2a cell and rat brain proteins. In the cases of artemether, dihydroartemisinin, and arteether, haemin (ferriprotoporphyrin IX) significantly increased the dose-related inhibition of neurite outgrowth from differentiating NB2a cells and significantly increased the dose-dependent inhibition of MTT metabolism. Inhibition of neurite outgrowth and metabolism of MTT in the presence or absence of haemin ranged from 72% to 93% and from 27% to 49% at a drug concentration of 300 nM. Haemin also significantly increased the dose-related binding of radiolabelled dihydroartemisinin to proteins from NB2a cells approximately twofold and to rat brain between three- and sixfold. Haemin did not enhance the neurotoxicity of desoxyarteether, a structural analogue of arteether with an ether linkage in the place of the endoperoxide bridge. It is suggested that haemin may catalyse the transformation of these derivatives via an interaction with the endoperoxide bridge of the artemisinin derivative to produce free radicals or electrophilic intermediates that are toxic to neuronal cells.
利用图像分析检测神经突生长，并通过分光光度法测量神经母细胞瘤细胞系NB2a中四氮唑盐MTT（3-(4,5-二甲基噻唑-2-基)-2,5-二苯基溴化四氮唑）的细胞代谢；检测放射性标记的二氢青蒿素与NB2a细胞和大鼠脑蛋白的结合情况。对于蒿甲醚、二氢青蒿素和蒿乙醚，血红素（高铁原卟啉IX）显著增强了对分化的NB2a细胞神经突生长的剂量相关性抑制，并显著增强了对MTT代谢的剂量依赖性抑制。在存在或不存在血红素的情况下，当药物浓度为300 nM时，神经突生长抑制率和MTT代谢抑制率分别为72%至93%和27%至49%。血红素还显著增强了放射性标记的二氢青蒿素与NB2a细胞蛋白的剂量相关性结合，约为原来的两倍，与大鼠脑蛋白的结合增强了三至六倍。血红素并未增强去氧蒿乙醚的神经毒性，去氧蒿乙醚是蒿乙醚的结构类似物，其醚键取代了内过氧化物桥。有人提出，血红素可能通过与青蒿素衍生物的内过氧化物桥相互作用，催化这些衍生物的转化，产生对神经细胞有毒的自由基或亲电中间体。
