Zarković N, Kalisnik T, Loncarić I, Borović S, Mang S, Kissel D, Konitzer M, Jurin M, Grainza S
Rudjer Bosković Institute, Dept. of Molecular Medicine, Zagreb, Croatia.
Cancer Biother Radiopharm. 1998 Apr;13(2):121-31. doi: 10.1089/cbr.1998.13.121.
Numerous findings indicate that specific plant lectins acting against cancer could be major active components of Viscum album extracts, although activity of low molecular weight components (peptides, carbohydrates and alkaloids) might be as essential for the beneficial activity of the plain plant extracts, too. Thus, active principle of Viscum album extracts is still not understood, and is difficult to be analysed because of the complex composition of the extracts and uncertainty of the standardised effectiveness (batch consistency) of the extracts. The aims of this study were to compare the concentration dependent effects of the pure mistletoe lectin (ML-1) with the fresh plant Viscum album extract (Isorel) and its different MW components on the in vitro growth of ConA stimulated lymphocytes, on the growth and tumorigenicity (artificial lung metastases development) of murine melanoma B16F10 cells, and to compare concentration dependent effects of the different types of the Viscum album extracts in vitro (applying novel type of MTT assay). The results obtained indicate that the effects of Isorel used at high dose could be result of toxic activity of the mistletoe lectins ("ML-1 like" activity). Unlike ML-1, if used at low concentrations, Isorel selectively inhibited tumor cells, due the activity of the low MW components. On the other hand, the number of tumor nodules was reduced (in comparison to the control) equally in the lungs of mice injected with B16F10 cells pre-treated in vitro with the plain Viscum album extract or any of its modifications or ML-1. Hence, it is supposed that the beneficial therapeutic effects of Isorel might result from the combined biological activity of the high and the low MW components not lectins only. Similarly, in MTT assay low concentrations of all types of the Viscum album extract showed stronger inhibiting activity for B16F10 and HeLa cells than pure ML-1. According to these results we propose a standardisation of aqueous Viscum album extracts by comparing their and ML-1 concentration dependent activity on the tumor cells in vitro applying MTT bioassay described which should be relevant for further evaluation of their active principle and for improvement of biotherapy of cancer.
众多研究结果表明，尽管低分子量成分（肽、碳水化合物和生物碱）的活性对于普通植物提取物的有益活性可能同样至关重要，但作用于癌症的特定植物凝集素可能是欧洲槲寄生提取物的主要活性成分。因此，欧洲槲寄生提取物的活性成分仍不明确，且由于提取物成分复杂以及提取物标准化有效性（批次一致性）的不确定性，难以进行分析。本研究的目的是比较纯槲寄生凝集素（ML-1）、新鲜植物欧洲槲寄生提取物（Isorel）及其不同分子量成分对刀豆蛋白A刺激的淋巴细胞体外生长、小鼠黑色素瘤B16F10细胞生长和致瘤性（人工肺转移发展）的浓度依赖性影响，并比较不同类型欧洲槲寄生提取物在体外的浓度依赖性影响（应用新型MTT法）。所得结果表明，高剂量使用的Isorel的作用可能是槲寄生凝集素毒性活性（“类ML-1”活性）的结果。与ML-1不同，低浓度使用时，Isorel由于低分子量成分的活性而选择性抑制肿瘤细胞。另一方面，在体外预先用普通欧洲槲寄生提取物或其任何变体或ML-1处理过的B16F10细胞注射的小鼠肺部，肿瘤结节数量（与对照相比）同样减少。因此，推测Isorel的有益治疗作用可能源于高分子量和低分子量成分的联合生物活性，而不仅仅是凝集素。同样，在MTT试验中，所有类型欧洲槲寄生提取物的低浓度对B16F10和HeLa细胞的抑制活性均强于纯ML-1。根据这些结果，我们建议通过比较其和ML-1在体外对肿瘤细胞的浓度依赖性活性，应用所描述的MTT生物测定法对水性欧洲槲寄生提取物进行标准化，这对于进一步评估其活性成分以及改善癌症生物治疗应具有相关性。
