The objective of this study was to evaluate four new 68Ga-labeled 1,4,7,10-cyclododeca-1,4,7,10-tetraacetic acid (DOTA)/1,4,7-triazacyclononane-1,4,7-triacetic acid derived (NODAGA)-glycine/hippurate conjugates and select a lead candidate for potential application in positron emission tomography (PET) renography. The non-metallated conjugates were synthesized by a solid phase peptide synthesis method. The 68Ga labeling was achieved by reacting an excess of the non-metallated conjugate with 68GaCl4− at pH −4.5 and 10-min incubation either at room temperature for NODAGA or 90 °C for DOTA. Radiochemical purity of all 68Ga conjugates was found to be >98%. 68Ga-NODAGA-glycine displayed the lowest serum protein binding (0.4%) in vitro among the four 68Ga conjugates. Biodistribution of 68Ga conjugates in healthy Sprague Dawley rats at 1-h post-injection revealed an efficient clearance from circulation primarily through the renal–urinary pathway with <0.2% of injected dose per gram remaining in the blood. The kidney/blood and kidney/muscle ratios of 68Ga-NODAGA-glycine were significantly higher than other 68Ga conjugates. On the basis of these results, 68Ga-NODAGA-glycine was selected as the lead candidate. 68Ga-NODAGA-glycine PET renograms obtained in healthy rats suggest 68Ga-NODAGA-glycine as a PET alternate of 99mTc-Diethylenetriaminepentaacetic acid (DTPA).
本研究的目的是评估四种新的 68Ga 标记的 1,4,7,10-cyclododeca-1,4,7,10-
四乙酸 (DOTA)/1,4,7-triazacyclononane-1,4,7 -
三乙酸衍生(N
ODAGA)-甘
氨酸/
马尿酸缀合物,并选择在正电子发射断层扫描(PET)肾造影中潜在应用的主要候选者。通过固相肽合成方法合成非
金属化缀合物。 68Ga 标记是通过将过量的非
金属化缀合物与 68GaCl4− 在 pH -4.5 下反应并在室温(对于 N
ODAGA)或 90°C(对于 DOTA)孵育 10 分钟来实现的。所有 68Ga 缀合物的放射
化学纯度均 >98%。在四种 68Ga 缀合物中,68Ga-N
ODAGA-甘
氨酸在体外表现出最低的血清蛋白结合 (0.4%)。注射后 1 小时,健康 Sprague Dawley 大鼠体内 68Ga 缀合物的
生物分布显示,主要通过肾脏-泌尿途径从循环中有效清除,血液中残留的每克注射剂量 <0.2%。 68Ga-NODAGA-甘氨酸的肾/血液和肾/肌肉比率显着高于其他68Ga缀合物。根据这些结果,68Ga-NODAGA-甘氨酸被选为主要候选物。在健康大鼠中获得的 68Ga-NODAGA-甘氨酸 PET 肾图表明 68Ga-NODAGA-甘氨酸可作为 99mTc-二亚乙基三胺五乙酸 (
DTPA) 的 PET 替代品。