Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggassstrasse 122, CH-3012 Berne, Switzerland.
College of Pharmacy, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE, USA.
Int J Antimicrob Agents. 2014 Jan;43(1):40-6. doi: 10.1016/j.ijantimicag.2013.09.012. Epub 2013 Oct 23.
Artemisinin is an antimalarial sesquiterpene lactone that contains a 1,2,4-trioxane heterocycle. Dihydroartemisinin and artesunate demonstrated activity against Echinococcus multilocularis metacestodes in vitro but were not effective in a mouse model. In this study, the in vitro effects of a small library of synthetic ozonides (1,2,4-trioxolanes) were investigated. Initial compound screening against E. multilocularis metacestodes was performed at 20μM, and selected ozonides were further assessed in dose-response studies in metacestode cultures and mammalian cells. Transmission electron microscopy (TEM) was employed to characterise compound-induced structural alterations. At 20μM, the most potent ozonides (OZ401, OZ455, OZ491 and OZ494) led to death of ca. 60-100% of the parasites. Subsequent dose-response experiments demonstrated that OZ401, OZ455 and OZ491, which contain an aminopropylether substructure, were the most potent, with 50% inhibitory concentrations ranging from 11μM to 14μM. Cytotoxicity for these three ozonides, assessed in human foreskin fibroblasts, rat hepatoma cells and green monkey epithelial kidney (Vero) cells, was evident only at high concentrations. TEM demonstrated that OZ401 and OZ491 treatment induced considerable metabolic impairment in metacestodes at 1 day post exposure. At Day 3 post exposure, the germinal layer was severely distorted, although some intact cells were still visible, demonstrating that not all cell types in the parasite tissue were equally affected. Complete destruction of the germinal layer was noted at 5 days post exposure. Synthetic ozonides could represent interesting leads that will be further investigated in a suitable in vivo model of E. multilocularis infection.
青蒿素是一种抗疟倍半萜内酯，含有 1,2,4-三氧杂环戊烷杂环。二氢青蒿素和青蒿琥酯在体外对泡状棘球蚴原头蚴表现出活性，但在小鼠模型中无效。在这项研究中，研究了一小部分合成臭氧化物（1,2,4-三氧杂环戊烷）的体外作用。最初针对泡状棘球蚴原头蚴的化合物筛选在 20μM 下进行，选择的臭氧化物在原头蚴培养物和哺乳动物细胞中的剂量反应研究中进一步评估。透射电子显微镜 (TEM) 用于描述化合物诱导的结构改变。在 20μM 时，最有效的臭氧化物（OZ401、OZ455、OZ491 和 OZ494）导致约 60-100%的寄生虫死亡。随后的剂量反应实验表明，含有氨基丙基醚结构的 OZ401、OZ455 和 OZ491 是最有效的，50%抑制浓度范围为 11μM 至 14μM。在人包皮成纤维细胞、大鼠肝癌细胞和绿猴上皮肾 (Vero) 细胞中评估这三种臭氧化物的细胞毒性仅在高浓度时才明显。TEM 表明，OZ401 和 OZ491 处理在暴露后 1 天诱导原头蚴发生相当大的代谢损伤。在暴露后第 3 天，生殖层严重变形，尽管仍可见一些完整的细胞，表明寄生虫组织中的并非所有细胞类型都受到同等影响。在暴露后第 5 天，生殖层完全被破坏。合成臭氧化物可能代表有趣的先导化合物，将在合适的泡状棘球蚴感染体内模型中进一步研究。
