Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto - FCFRP-USP, Universidade de São Paulo, Avenida do Café s/n, 14040-903, Ribeirão Preto, SP, Brazil.
Núcleo de Desenvolvimento de Compostos Bioativos (NDCBio), Universidade Federal do Triângulo Mineiro, Av. Dr. Randolfo Borges 1400, 38025-440, Uberaba, MG, Brazil.
Eur J Med Chem. 2019 Oct 15;180:213-223. doi: 10.1016/j.ejmech.2019.07.014. Epub 2019 Jul 5.
Reactions of Ni(II) and Pd(II) precursors with S-benzyl-N-(ferrocenyl)methylenedithiocarbazate (HFedtc) led to the formation of heterobimetallic complexes of the type [M(Fedtc)] (M = Ni and Pd). The characterization of the compounds involved the determination of melting point, FTIR, UV-Vis, H NMR, elemental analysis and electrochemical experiments. Furthermore, the crystalline structures of HFedtc and [Ni(Fedtc)] were determined by single crystal X-ray diffraction. The compounds were evaluated against the intracellular form of Trypanosoma cruzi (Tulahuen Lac-Z strain) and the cytotoxicity assays were assessed using LLC-MK2 cells. The results showed that the coordination of HFedtc to Ni(II) or Pd(II) decreases the in vitro trypanocidal activity while the cytotoxicity against LLC-MK2 cells does not change significantly. [Pd(Fedtc)] showed the greater potential between the two complexes studied, showing an SI value of 8.9. However, this value is not better than that of the free ligand with an SI of 40, a similar value to that of the standard drug benznidazole (SI = 48). Additionally, molecular docking simulations were performed with Trypanosoma cruzi Old Yellow Enzyme (TcOYE), which predicted that HFedtc binds to the protein, almost parallel to the flavin mononucleotide (FMN) prosthetic group, while the [Ni(Fedtc)] complex was docked into the enzyme binding site in a significantly different manner. In order to confirm the hypothetical interaction, in vitro experiments of fluorescence quenching and enzymatic activity were performed which indicated that, although HFedtc was not processed by the enzyme, it was able to act as a competitive inhibitor, blocking the hydride transfer from the FMN prosthetic group of the enzyme to the menadione substrate.
镍（II）和钯（II）前体与 S-苄基-N-（二茂铁基）亚甲基二硫代氨基甲酸盐（HFedtc）的反应导致了[M（Fedtc）]（M=Ni 和 Pd）型杂双金属配合物的形成。化合物的表征涉及熔点、FTIR、UV-Vis、H NMR、元素分析和电化学实验的确定。此外，通过单晶 X 射线衍射确定了 HFedtc 和[Ni（Fedtc）]的晶体结构。评估了这些化合物对 Trypanosoma cruzi（Tulahuen Lac-Z 株）细胞内形式的作用，并使用 LLC-MK2 细胞评估了细胞毒性测定。结果表明，HFedtc 与 Ni(II)或 Pd(II)的配位降低了体外杀锥虫活性，而对 LLC-MK2 细胞的细胞毒性没有明显变化。与研究的两个配合物相比，[Pd（Fedtc）]显示出更大的潜力，具有 8.9 的 SI 值。然而，该值并不优于具有 40 的 SI 值的游离配体，与标准药物苯并咪唑（SI=48）的值相似。此外，还对 Trypanosoma cruzi Old Yellow Enzyme（TcOYE）进行了分子对接模拟，预测 HFedtc 与该蛋白结合，几乎与黄素单核苷酸（FMN）辅基平行，而[Ni（Fedtc）]复合物则以明显不同的方式对接在酶的结合位点上。为了确认假设的相互作用，进行了荧光猝灭和酶活性的体外实验，表明尽管 HFedtc 未被酶处理，但它能够作为竞争性抑制剂，阻止 FMN 辅基的氢化物从酶转移到 menadione 底物。
