Purity >98%. Fingolimod is a derivative of ISP-1 (myriocin), a fungal metabolite of the Chinese herb Iscaria sinclarii as well as a structural analog of sphingosine. It is a novel immune modulator that prolongs allograft transplant survival in numerous models by inhibiting lymphocyte emigration from lymphoid organs. Fingolimod is phosphorylated by sphingosine kinase, which then acts as a potent agonist at four of the sphingosine-1-phosphate (S1P) receptors (S1P1, S1P3, S1P4, and S1P5 ). Down-regulation of S1P1 receptors on T and B lymphocytes by fingolimod results in defective egress of these cells from spleen, lymph nodes, and Peyer's patch. Fingolimod also enhances the activity of the sphingosine transporter Abcb1 and the leukotriene C4 transporter Abcc1 and inhibits cytosolic phospholipase A2 activity.