In vitro and in vivo evaluation of technetium-99m-labeled propylene amine oxime complexes containing nitroimidazole and nitrotriazole groups as hypoxia markers

Hypoxia markers have been the subject of intensive research in radiopharmaceuticals, but there is little work on markers with multi-redox centers. It is necessary to further develop and investigate the compounds containing multi-redox centers systematically. Two propylene amine oxime ligands, compound 1, containing 3-nitro-1,2,4-triazole and 4-nitroimidazole and compound 2, containing 3-nitro-1,2,4-triazole and 2-nitroimidazole were synthesized and radiolabeled with (99m) Tc; then these complexes were also evaluated in vitro and in vivo. Some comparisons were made with the other complexes of our previous work, and some interesting conclusions were obtained. Tc-99m-1 and Tc-99m-2 displayed significant hypoxic/normoxic differentials in both S180 and H22 cell lines. These complexes held moderate tumor-to-blood and tumor-to-muscle ratios, indicating they might serve as novel hypoxia markers. Some comparisons showed the in vitro evaluation may be connected with the number and the type of the redox centers, and the biodistribution experiments may have relation with the hydrophilicity and the type of redox centers.