Complexes of <i>myo</i>-inositol-hexakisphosphate (InsP6) with zinc or lanthanum to enhance excretion of radioactive strontium from the body

<div><p>⁹⁰Sr, which was released into the atmosphere and the ocean following the Chernobyl and Fukushima Daiichi nuclear power plant disasters, is an important nuclear fission element. Compounds that inhibit the absorption of ⁹⁰Sr into the bloodstream and enhance its elimination can be beneficial in decreasing the absorbed radiation dose in people exposed to ⁹⁰Sr. Recently, we prepared complexes of <i>myo</i>-inositol-hexakisphosphate (InsP6) with zinc or lanthanum as decorporation agents. These complexes, called Zn-InsP6 and La-InsP6 respectively, are insoluble in water and can potentially chelate additional metal cations. Hypothesizing that these complexes can assist the excretion of ⁹⁰Sr from the body, we evaluated them using ⁸⁵Sr instead of ⁹⁰Sr. In <i>in vitro</i> binding experiments, Zn-InsP6 showed higher strontium adsorption capacity than La-InsP6. We then performed <i>in vivo</i> biodistribution experiments of Zn-InsP6 in mice after oral administration of ⁸⁵SrCl₂. Mice treated with Zn-InsP6 showed significantly lower bone accumulation of radioactivity than mice in a non-treatment control group. Zn-InsP6 adsorbed radiostrontium in the gastrointestinal tract, inhibited this ion’s absorption into the bloodstream, and enhanced its excretion in the feces. Therefore, Zn-InsP6 appears to be a promising ⁹⁰Sr “decorporation” agent.</p>