Synthesis and evaluation of the novel 2-[¹⁸F]fluoro-3-propoxy-triazole-pyridine-substituted losartan for imaging AT₁ receptors.

The 2-[(18)F]fluoro-3-pent-4-yn-1-yloxypyridine ([(18)F]FPyKYNE) analog of the potent non-peptide angiotensin II type 1 receptor (AT1R) blocker losartan was produced via click chemistry linking [(18)F]FPyKYNE to azide-modified tetrazole-protected losartan followed by TFA deprotection. Preliminary small animal imaging with positron emission tomography (PET) in rats displayed high uptake in the kidneys with good contrast to surrounding tissue. Rat metabolism displayed the presence of 23% unchanged tracer in plasma at 30 min.

Radiosynthesis of N-[(11)C]-methyl-hydroxyfasudil as a new potential PET radiotracer for rho-kinases (ROCKs).

N-[(11)C]-methyl-hydroxyfasudil was synthesized as a new potential radiotracer for rho-kinases (ROCKs) via a two-step one-pot radiosynthesis. The first step was the methylation of the precursor N-Boc-hydroxyfasudil-sodium salt/benzo-15-crown-5 complex with [(11)C]methyl iodide. The second step involved deprotection of the tert-butoxycarbonyl protecting group.