Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Defence Research and Development Organization, Brig S K. Mazumdar Road, Delhi 54, India.
Bioconjug Chem. 2011 Feb 16;22(2):244-55. doi: 10.1021/bc100382c. Epub 2011 Jan 11.
A phosphonate derivative 10'-bis(acetamido)-ethane-bis[1,4,7-tri(methylene phosphonic acid)-1,4,7,10-tetraazacyclododecane] (DO3P-AME-DO3P), was synthesized with 90% yield in high purity. It was labeled with (99m)Tc in 97.5% efficiency and specific activity of 112-250 MBq/μmol. The binding affinity of (99m)Tc-DO3P-AME-DO3P towards bone minerals was tested in vitro by using hydroxy apatite as a bone model with absorption of 93% during the first hour of the experiment. Receptor binding assay on human bone cell line SAOS-2 demonstrated K(d) value of 1.07 nM. Cell binding studies of DO3P-AME-DO3P on osteoblasts and osteoclasts cells performed in vitro displayed preferential affinity of the compound towards osteoclast (167.95 ± 3.56% dose/mg protein). The serum stability of (99m)Tc complex was found to be 96.8% after 24 h. Blood kinetics of (99m)Tc-DO3P-AME-DO3P performed on normal rabbits showed fast clearance with t(1/2)(F) = 15 min ± 0.014 min and t(1/2)(S) = 4 h 3 min ± 0.09 min. Biodistribution studies carried out in normal BALB/c mice showed bone-to-blood ratio of 20 and bone-to-muscle ratio of 33. The bone tissue demonstrated highest concentration of bound radioactivity with 10.73% ID/g at 1 h post injection. The protonation and stability constants were determined by pH-potentiometry titrations. The stability constants of DO3P-AME-DO3P with Lu(III), Sm(III), and Ho(III) were 19.7, 21.8, and 20.2 determined by "out of cell" method. The excellent bone seeking properties of DO3P-AME-DO3P make it a candidate of choice for SPECT imaging and preferential uptake of the compound in osteoclasts in comparison to osteoblasts; BMM and BMC can be used to understand the pathway of pathogenesis of osteoporosis and skeletal metastases.
一种膦酸酯衍生物 10'-双(乙酰氨基)-乙烷-双[1,4,7-三(亚甲基膦酸)-1,4,7,10-四氮杂环十二烷](DO3P-AME-DO3P),以 90%的产率和 97.5%的效率和 112-250MBq/μmol 的比活度在高纯度下合成。它以(99m)Tc 标记,标记效率为 97.5%,比活度为 112-250MBq/μmol。通过使用羟基磷灰石作为骨模型,在实验的第一个小时内吸收 93%,在体外测试了(99m)Tc-DO3P-AME-DO3P 对骨矿物质的结合亲和力。在人骨肉瘤细胞系 SAOS-2 上进行的受体结合测定表明 K(d)值为 1.07nM。在体外进行的 DO3P-AME-DO3P 对成骨细胞和破骨细胞的细胞结合研究显示,该化合物对破骨细胞具有优先亲和力(167.95±3.56%剂量/mg 蛋白)。(99m)Tc 配合物的血清稳定性在 24 小时后发现为 96.8%。在正常兔中进行的(99m)Tc-DO3P-AME-DO3P 的血液动力学研究显示,清除速度快,t(1/2)(F)=15min±0.014min,t(1/2)(S)=4h3min±0.09min。在正常 BALB/c 小鼠中进行的生物分布研究显示,骨/血比为 20,骨/肌比为 33。骨组织在注射后 1 小时显示出最高的放射性结合浓度,为 10.73%ID/g。通过 pH 电位滴定法确定了质子化和稳定常数。通过“细胞外”法确定了 DO3P-AME-DO3P 与 Lu(III)、Sm(III)和 Ho(III)的稳定常数分别为 19.7、21.8 和 20.2。DO3P-AME-DO3P 的优异骨靶向特性使其成为 SPECT 成像的候选物,与成骨细胞相比,该化合物在破骨细胞中的优先摄取;BMM 和 BMC 可用于了解骨质疏松症和骨骼转移的发病途径。