摘要:
To continue our efforts toward the development of Tc-99m PiB analogs, we have synthesized 24 neutral and lipophilic Re (as a surrogate of Tc-99m) 2-arylbenzothiazoles, and explored their structure-activity relationship for binding to A beta(1-40) fibrils. These Re complexes were designed and synthesized via the integrated approach, so their 99mTc analogs would have a greater chance of crossing the blood-brain barrier. While the lipophilicities (logP(C18) = 1.59-3.53) of these Re 2-arylbenzothiazoles were all within suitable range, their binding affinities (K-i = 30-617 nM) to A beta(1-40) fibrils varied widely depending on the selection and integration of the tetradentate chelator into the 2-phenylbenzothiazole pharmacophore. For potential clinical applications, further refinement to obtain Re 2-arylbenzothiazoles with better binding affinities (<10 nM) will likely be needed. The integrated approach reported here to generate compact, neutral and lipophilic Re 2-arylbenzothiazoles could be applied to other potent pharmacophores as well to convert other current Ab PET tracers to their Tc-99m analogs for more widespread application via the use of SPECT scanners. (C) 2013 Elsevier Ltd. All rights reserved.