11C labelled benzofuran derivatives as a new agent for β-amyloid imaging

Objective: Deposit of β-amyloid protein (Aβ) as senile plaque is one of the pathophysiologic features in Alzheimer's disease. Several new derivatives of benzofuran were synthesized, 11C labelled, and tested as the potential imaging agents for targeting amyloid deposit. Methods: 5-Br-2-(4-aminophenyl) benzofuran was synthesized and labelled by an improved method, in which the precursors were mixed with 11CH3I and dimethyl sulfoxide (DMSO) solution to get 5-Br-2-(4-N-11C-methylaminophenyl) benzofuran. The column method was employed to measure the labelling yields. The biodistribution of the product was studied in 9 normal mice. The characters of the precursor were confirmed by 1H NMR. Results: The labelling yield was 45% with the author's improved method used in the current study. The radiochemical yield was over 95%. Most of the radioactivity was observed in liver and kidney after intravenous injection. The peak uptake in normal mice brain (3.2% ID/g) was noted at 2 min post-injection with a washout faster for 5-Br-substituent than 5-I-substituent. The 2/30 min ratio of cerebral uptake was 1.34. Conclusion: The new derivative, 11C labelled 5-Br-substituent, showed certain characteristics more favorable than literature reported 5-I-substituent as an Aβ imaging agent. (authors)