Complexes of myo-Inositol-Hexakisphosphate (IP6) with Zinc or Lanthanum for the Decorporation of Radiocesium.

Radioactive nuclides leak into the surrounding environment after nuclear power plant disasters, such as the Chernobyl accident and the Fukushima Daiichi Nuclear Power Plant disaster. Cesium-137 ((137)Cs) (t1/2=30.1 year), a water-soluble radionuclide with a long physical half-life, contaminates aquatic ecosystems and food products. In humans, (137)Cs concentrates in muscle tissue and has a long biological half-life, indicating it may be harmful. myo-Inositol-hexakisphosphate (IP6) is a compound found in grain, beans, and oil seeds. IP6 has the ability to form insoluble complexes with metals, including lanthanum (La) and zinc (Zn). We hypothesized that La-IP6 and Zn-IP6 may promote the elimination of (137)Cs from the body through the adsorption of La-IP6 and Zn-IP6 to (137)Cs in the gastrointestinal tract. Therefore, in this study, we evaluated the adsorptive capacity of La-IP6 and Zn-IP6 complexes with (137)Cs in vitro and in vivo. La-IP6 and Zn-IP6 complexes were stable in acidic solution (pH 1.2) at 37°C. In vitro binding assays indicated that La-IP6 and Zn-IP6 complexes adsorbed (137)Cs, with the adsorption capacity of Zn-IP6 to (137)Cs greater than that of La-IP6. To evaluate the usefulness of La-IP6 and Zn-IP6 in vivo, La-IP6 or Zn-IP6 was administrated to mice after intravenous injection of (137)Cs. However, the biodistribution of (137)Cs in the La-IP6 treated group and the Zn-IP6 treated group was nearly identical to the non-treated control group, indicating that La-IP6 and Zn-IP6 were not effective at promoting the elimination of (137)Cs in vivo.