In vivo detection of amyloid β deposition using ¹⁹F magnetic resonance imaging with a ¹⁹F-containing curcumin derivative in a mouse model of Alzheimer's disease.

Amyloid β (Aβ) deposition in the brain is considered the initiating event in the progression of Alzheimer's disease (AD). Amyloid imaging is widely studied in diagnosing AD and evaluating the disease stage, with considerable advances achieved in recent years. We have developed a novel ¹⁹F-containing curcumin derivative (named FMeC1) as a potential imaging agent. This compound can exist in equilibrium between keto and enol tautomers, with the enol form able to bind Aβ aggregates while the keto form cannot. This study investigated whether FMeC1 is suitable as a ¹⁹F magnetic resonance imaging (MRI) probe to detect Aβ deposition in the Tg2576 mouse, a model of AD. In ¹⁹F nuclear magnetic resonance (NMR) spectra obtained from the whole head, a delayed decreased rate of F ¹⁹F signal was observed in Tg2576 mice that were peripherally injected with FMeC1 in comparison to wild-type mice. Furthermore, ¹⁹F MRI displayed remarkable levels of ¹⁹F signal in the brain of Tg2576 mice after the injection of FMeC1. Histological analysis of FMeC1-injected mouse brain showed penetration of the compound across the blood-brain barrier and binding to Aβ plaques in peripherally injected Tg2576 mice. Moreover, the distribution of Aβ deposits in Tg2576 mice was in accordance with the region of the brain in which the ¹⁹F signal was imaged. FMeC1 also exhibited an affinity for senile plaques in human brain sections. These findings suggest the usefulness of FMeC1 as a ¹⁹F MRI probe for the detection of amyloid deposition in the brain. Furthermore, the properties of FMeC1 could form the basis for further novel amyloid imaging probes.