An S1P5 agonist that is selective for S1P5 over S1P1 and S1P3 (IC50s = 0.006, 0.362, and >10 μM, respectively); inhibits forskolin-induced cAMP production in CHO cells expressing S1P5 (EC50 = 4.1 nM); increases electrical resistance of hCMEC/D3 cells in an in vitro blood-brain barrier model at 1 μM; attenuates blood-brain barrier leakage in an R6/2 transgenic mouse model of Huntington's disease at 0.1 mg/kg; decreases the number of errors made in a horizontal ladder task and increases latency to fall in the rotarod test in R6/2 mice at 0.1 mg/kg; increases spontaneous alternation in the t-maze in aged mice at 0.1 mg/kg,