Synthesis, characterization and biological evaluation of tricarbonyl M(i) (M = Re, 99mTc) complexes functionalized with melanin-binding pharmacophores
作者:Carolina Moura、Teresa Esteves、Lurdes Gano、Paula D. Raposinho、António Paulo、Isabel Santos
DOI:10.1039/c0nj00256a
日期:——
Aiming to evaluate their potential as radioactive probes for in vivo targeting of melanotic melanoma and its metastases, we have synthesized 99mTc(I) tricarbonyl complexes (Tc1–Tc8) anchored by pyrazolyl-containing chelators with (N3) or (N2O) donor atom sets and functionalized with 2-aminoethyldiethylamine and 4-amino-N-(2-diethylaminoethyl)benzamide groups as melanin-binding pharmacophores. The chemical identification of the several 99mTc complexes has been accomplished by HPLC comparison with the Re congeners (Re1–Re8), which were synthesized at the macroscopic level and fully characterized by common analytical techniques. The biological evaluation of the 99mTc(I) complexes comprised the determination of their in vitro binding to synthetic melanin, measurement of cellular uptake in B16F1 murine melanoma cells, as well as biodistribution studies in B16F1 melanoma-bearing mice. All the tested complexes have shown a moderate to high in vitro affinity to melanin, with percentages of binding spanning between 60 and 94%. In agreement with the poor cellular uptake measured in vitro, the in vivo tumor uptake of the complexes was in general relatively low, ranging between 0.12 and 1.69% ID g−1 at 4 h p.i. However, some complexes have shown favorable tumor-to-organ ratios with values as high as 28 and 5.3 for tumor–muscle and tumor–blood ratios, respectively. This seems to indicate that some selectivity towards melanoma tissue was conserved, and encourages further optimization of the in vitro/in vivo biological properties of this type of complexes aimed at finding novel radioactive probes for non-invasive imaging of melanoma.
旨在评估其作为放射性探针在体内靶向黑色素瘤及其转移的潜力,我们合成了99mTc(I)三碳基络合物(Tc1–Tc8),这些络合物由含吡唑的螯合剂锚定,具有(N3)或(N2O)供体原子组,并用2-氨基乙基二乙胺和4-氨基-N-(2-二乙氨基乙基)苯酰胺作为与黑色素结合的药效团。通过与在宏观水平合成并经过常规分析技术充分表征的Re同类物(Re1–Re8)进行HPLC比较,完成了几种99mTc络合物的化学鉴定。99mTc(I)络合物的生物评估包括测定其与合成黑色素的体外结合,测量在B16F1小鼠黑色素瘤细胞中的细胞摄取,以及在B16F1黑色素瘤小鼠中的生物分布研究。所有测试的络合物均表现出对黑色素的中等到高的体外亲和力,结合百分比在60%到94%之间。与体外测得的较低细胞摄取相符,这些络合物在体内的肿瘤摄取通常相对较低,在4小时后注射的情况下,范围在0.12%到1.69% ID g−1。然而,一些络合物在肿瘤与器官的比率上表现出良好的肿瘤-肌肉和肿瘤-血液比率,分别高达28和5.3。这似乎表明对黑色素瘤组织的一定选择性得以保持,并鼓励进一步优化这类络合物的体外/体内生物特性,以寻找用于黑色素瘤非侵入性成像的新型放射性探针。