Synthesis and evaluation of fluorinated fingolimod (FTY720) analogues for sphingosine-1-phosphate receptor molecular imaging by positron emission tomography.

Sphingosine-1-phosphate (S1P) is a lysophospholipid that evokes a variety of biological responses via stimulation of a set of cognate G-protein coupled receptors (GPCRs): S1P1-S1P5. S1P and its receptors (S1PRs) play important roles in the immune, cardiovascular, and central nervous systems and have also been implicated in carcinogenesis. Recently, the S1P analogue Fingolimod (FTY720) has been approved for the treatment of patients with relapsing multiple sclerosis. This work presents the synthesis of various fluorinated structural analogues of FTY720, their in vitro and in vivo biological testing, and their development and application as [(18)F]radiotracers for the study of S1PR biodistribution and imaging in mice using small-animal positron emission tomography (PET).