Kakinuma J, Honjo Y, Orii H
Radioisotopes. 1982 Apr;31(4):175-8.
Cobalt-57-bleomycin (BLM) has been proven to be the most stable and useful tumor-diagnostic agent among several radiolabelled BLMs. However, the considerably long half life of 57Co causes troubles in handling and preclude its extensive uses. In our previous work, BLM was proved to form two geometrical isomers, in chelating with Co. In this paper, we compared the tumor affinity of two isomers, to make an improvement of this drug's merit. We investigated biodistribution in tumor-bearing mice and DNA binding properties by fluorescence quenching technique and DNA melting study. A comparison of the data obtained suggests that isomerism affects the tumor affinity of the drug. Both tumor accumulation in tumor-bearing mice and stability of DNA binding of type I isomer were higher than those of type II. If a certain suitable radionuclide is inserted into cold Co-BLM type I isomer, this agent will be a greatly useful tumor-imaging radiopharmaceutical.
钴-57-博来霉素（BLM）已被证明是几种放射性标记博来霉素中最稳定且最有用的肿瘤诊断剂。然而，57Co相当长的半衰期给处理带来麻烦，并限制了其广泛应用。在我们之前的工作中，已证明博来霉素在与钴螯合时会形成两种几何异构体。在本文中，我们比较了两种异构体的肿瘤亲和力，以改进这种药物的优点。我们通过荧光猝灭技术和DNA熔解研究调查了荷瘤小鼠体内的生物分布和DNA结合特性。对所得数据的比较表明，异构现象会影响该药物的肿瘤亲和力。I型异构体在荷瘤小鼠体内的肿瘤蓄积和DNA结合稳定性均高于II型。如果将某种合适的放射性核素插入冷钴-BLM I型异构体中，这种试剂将成为一种非常有用的肿瘤显像放射性药物。
