We describe the synthesis and biological evaluation of the cationic 99mTc–tricarbonyl complex fac-[99mTc(CO)3(κ3-L1)]+ (Tc1) anchored by a pyrazole-diamine-methylbenzylguanidine-based ligand (L1), as potentially useful for myocardial imaging. The rhenium complex fac-[Re(CO)3(κ3-L1)]+ (Re1) was prepared and characterized as a ‘cold’ surrogate of the radioactive complex. Cell uptake studies in a neuroblastoma cell line suggest that Tc1 uptake mechanism is related to the norepinephrine transporter (NET). Tissue distribution studies in CD1 mice showed that Tc1 presents high initial heart uptake and a slow washout from the heart (7.8 ± 1.3% injected dose per gram (ID/g), 30-min post-injection (p.i.); 6.3 ± 1.3% ID/g, 60-min p.i.), with heart to blood ratios of 11.8 and 9.0 at 30- and 60-min p.i., respectively. The uptake mechanism of Tc1 appears to be similar to that of metaiodobenzylguanidine (MIBG), as it can be reduced by coinjection with nonradioactive MIBG. The biodistribution profile of Tc2, where the benzylguanidine pharmacophore is absent, corroborates the fact that Tc1 does not accumulate in the heart by a simple diffusion mechanism but rather by a NET-mediated mechanism. The results confirm those obtained in the cell assays. Despite the persistent heart uptake found for Tc1, the high hepatic and renal uptake remains to be improved.
我们描述了由
吡唑-二胺-甲基苄基
胍基
配体 (L1) 锚定的阳离子 99mTc-三羰基复合物 fac-[99mTc(CO)3(κ3-L1)]+ (Tc1) 的合成和
生物学评估,该复合物具有潜在的用途用于心肌成像。制备了
铼络合物 fac-[Re(CO)3(κ3-L1)]+ (Re1),并将其表征为放射性络合物的“冷”替代物。神经母细胞瘤
细胞系的细胞摄取研究表明,Tc1 摄取机制与
去甲肾上腺素转运蛋白 (NET) 有关。 CD1 小鼠的组织分布研究表明,Tc1 具有较高的初始心脏摄取量和从心脏的缓慢清除能力(每克注射剂量 (ID/g) 为 7.8±±1.3%,注射后 30 分钟 (p.i.);注射后 30 分钟 (p.i.);6.3±±1.3%) ID/g,注射后 60 分钟),注射后 30 分钟和 60 分钟时心血比分别为 11.8 和 9.0。 Tc1 的摄取机制似乎与间
碘苄基
胍 (MIBG) 相似,因为它可以通过与非放射性 MIBG 共注射来减少。 Tc2 的
生物分布特征(其中不存在苄基
胍药效团)证实了 Tc1 不是通过简单的扩散机制而是通过 NET 介导的机制在心脏中积聚的事实。结果证实了细胞测定中获得的结果。尽管心脏对 Tc1 的摄取持续存在,但肝脏和肾脏的高摄取仍有待改善。