Nitroimidazole-Containing H2dedpa and H2CHXdedpa Derivatives as Potential PET Imaging Agents of Hypoxia with 68Ga

68Ga is an attractive radiometal for use in positron emission tomography (PET) imaging. The success of 68Ga-based agents is dependent on a chelator that exhibits rapid radiometal incorporation, and strong kinetic inertness to prevent transchelation of 68Ga in vivo. The linear chelating agents H2dedpa (1,2-[[6-carboxypyridin-2-yl]methylamino]ethane) and H2CHXdedpa (CHX = cyclohexyl/cyclohexane) (N4O2) have recently been developed that bind Ga3+ quickly and under mild conditions, ideal properties to be incorporated into a 68Ga PET imaging agent. Herein, nitroimidazole (NI) derivatives of H2dedpa and H2CHXdedpa to investigate specific targeting of hypoxic tumor cells are investigated, given that NI can be reduced and retained exclusively in hypoxic cells. Nine N,N′-bis-alkylated derivatives of H2dedpa and H2CHXdedpa have been synthesized; they have been screened for their ability to bind gallium, and cyclic voltammetry of nonradioactive complexes was performed to probe the redox cycling mechanism of NI. The ...