Synthesis, radiolabeling and stability of new nitrophenol complexes of ^99mTc as possible hypoxia imaging radiopharmaceuticals

Summary

The synthesis of the seven ^99mTc-labeled nitrophenol radiosensitizers (N₂OS chelates) was undertaken for evaluation of their biostability in vitro as possible hypoxia tumor imaging agents. The title compounds (2-7)were successively synthesized, characterized, and finally radiolabeled (^99mTc-NaTcO₄, stannous chloride, pH 10) to obtain the new complexes (8a-8f) for evaluation. The purity and stability of the final complexes (in human and rat serum) were evaluated by chromatographic methods (radio-TLC, ITLC, HPLC). The most stable complex over 6 hours was shown to be ^99mTc-labeled 3-[3'-N-(2”-hydroxy-5”-nitrobenzylamino)-2'-propanol]-1-(4'-methyl)thiourea (8e). Biodistribution studies of 8ein tumor-bearing rats are under investigation.