Faculty of Chemical Sciences, University of Concepción, Chile.
Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, CU, 04510, Mexico.
J Inorg Biochem. 2018 Jan;178:87-93. doi: 10.1016/j.jinorgbio.2017.10.009. Epub 2017 Nov 6.
Two cytotoxic copper(II) complexes with N-H and N-methylated benzimidazole-derived ligands (Cu-L and Cu-L; L=bis(2-methylbenzimidazolyl)(2-methylthioethyl)amine, L=bis(1-methyl-2-methylbenzimidazolyl)(2-methylthioethyl)amine) were synthesized and exposed to human erythrocytes and molecular models of its membrane. The latter were bilayers built-up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), classes of lipids present in the external and internal moieties of the human red cell membrane, respectively. Scanning electron microscopy (SEM) of erythrocytes incubated with solutions of both Cu(II) complexes showed that they induced morphological changes to the normal cells to echinocytes, and hemolysis at higher concentrations. Real-time observation of the dose-dependent effects of the complexes on live erythrocytes by defocusing microscopy (DM) confirmed SEM results. The formation of echinocytes implied that complex molecules inserted into the outer moiety of the red cell membrane. X-ray diffraction studies on DMPC and DMPE showed that none of these complexes interacted with DMPE and only Cu-L interacted with DMPC. This difference was explained by the fact that Cu-L complex is more voluminous than Cu-L because it has two additional methyl groups; on the other hand, DMPC molecule has three methyl groups in its bulky terminal amino end. Thus, by steric hindrance Cu-L molecules cannot intercalate into DMPC bilayer, which besides is present in the gel phase. These results, together with the increased antiproliferative capacity of the N-methylated complex Cu-L over that of Cu-L are rationalized mainly based on its higher lipophilicity.
两种具有 N-H 和 N-甲基苯并咪唑衍生配体的细胞毒性铜（II）配合物（Cu-L 和 Cu-L；L=双（2-甲基苯并咪唑基）（2-甲基硫乙基）胺，L=双（1-甲基-2-甲基苯并咪唑基）（2-甲基硫乙基）胺）被合成并暴露于人类红细胞及其膜的分子模型。后者是由二肉豆蔻酰磷脂酰胆碱（DMPC）和二肉豆蔻酰磷脂酰乙醇胺（DMPE）构建的双层，分别是人类红细胞膜外部和内部部分存在的脂质类别。与两种 Cu（II）配合物溶液孵育的红细胞的扫描电子显微镜（SEM）显示，它们诱导正常细胞发生形态变化为棘红细胞，并且在较高浓度下发生溶血。通过离焦显微镜（DM）实时观察复合物对活红细胞的剂量依赖性影响，证实了 SEM 结果。棘红细胞的形成表明配合物分子插入红细胞膜的外部部分。对 DMPC 和 DMPE 的 X 射线衍射研究表明，这些配合物均不与 DMPE 相互作用，只有 Cu-L 与 DMPC 相互作用。这种差异可以通过以下事实来解释：由于 Cu-L 配合物具有两个额外的甲基基团，因此它比 Cu-L 配合物体积更大；另一方面，DMPC 分子在其庞大的末端氨基末端具有三个甲基基团。因此，由于空间位阻，Cu-L 分子不能插入到 DMPC 双层中，而且 DMPC 双层还存在于凝胶相中。这些结果以及 N-甲基化配合物 Cu-L 的增殖抑制能力比 Cu-L 更强，主要基于其更高的亲脂性得到了合理化。
