Divalent 2-(4-Hydroxyphenyl)benzothiazole Bifunctional Chelators for 64Cu Positron Emission Tomography Imaging in Alzheimer's Disease

Herein, we report a new series of divalent 2-(4-hydroxyphenyl)benzothiazole bifunctional chelators (BFCs) with high affinity for amyloid fi aggregates and favorable lipophilicity for blood-brain barrier penetration. The addition of an alkyl carboxylate ester pendant arm offers high binding affinity toward Cu(II). The novel BFCs form stable 64Cu-radiolabeled complexes and exhibit promising partition coefficient (logD) values of 1.05-1.85. Among the five compounds tested, the 64Cu-YIN-15 complex exhibits significant staining of amyloid fi plaques in ex vivo autoradiography studies. In addition, biodistribution studies show that 64Cu-YIN-15-Me exhibits moderate brain uptake (0.69 +/- 0.08 %ID/g) in wild type mice.