Radiosynthesis of [103Pd]-di-actyl-bis (N4-methylthiosemicarbazone): a potential therapeutic agent

Background: Due to interesting tumor imaging properties of bis-thiosemicarbazones, [103Pd]-di-acetyl-bis (N4-methylthiosemicarbazone) ([103Pd] ATSM2) was prepared according to the analogy of radio copper homologues. Materials and Methods: Palladium-103 (T1/2=16.96 d) was produced via the 103Rh (p,n) 103Pd nuclear reaction with proton energy 18 MeV. The final activity was eluted in form of Pd (NH4)2Cl2 in order to react with bis-thiosemicarbazones to yield [103Pd]-labeled compounds. Chemical purity of the final product was confirmed to be below the accepted limits by polarography. The labeled compound was purified by reverse phase column chromatography using C18 plus Sep-Pak. The partition co-efficient of the final complexes were determined. The initial physico-chemical properties of the labeled compounds were compared to those of their copper homologues. Results: Radiochemical purity of more than 99% using RTLC was obtained (specific activity of about 12500-13000 Ci/mol). The stability of the tracer was checked in final product and human serum, at 37C up to 48h. Conclusion: The labeled compound prepared in this study is probably one of the few new 103pd-radiolabeled compounds which have a potential for future biological studies, regarding its suitable physicochemical stability.