[Biochemistry of amino acid derivatives of [103Ru] ruthenocene. Comparison with 131I hippuran].

The potential radiopharmaceuticals: ruthenocenoyl alanine, ruthenocenoyl methionine, 1'-methyl-ruthenocenoyl glycine and its esters were labelled with 103Ru starting from the analogous ferrocene compounds. In a series of tests in mice and rats these substances were compared with hippuran and ruppuran (= ruthernocenoyl glycine, a ruthenocene-amino acid analogue of hippuran). The organ distribution of these compounds was measured at various times after injection. Kidney concentrations of 1'-methyl-ruthenocenoyl glycine and its esters were found to be extremely high, followed by a rapid excretion. In contrast with these compounds, ruthenocenoyl methionine indicated a significantly greater affinity for liver than for kidney, but not for pancreas. Ruthenocenoyl alanine exhibits a high affinity for tumor cells. The advantages of 97Ru labelled radiopharmaceuticals compared with 99mTc or 123I/131I labelled compounds are discussed.