SLF1081851 is a Spns2 inhibitor, inhibits S1P release ( IC 50 =1.93 μM). SLF1081851 plays a key role in development and immune system In Vitro Sphingosine 1-phosphate (S1P) is a pleiotropic signaling molecule, and Spns2 exerts the functions to maintain lymph S1P. SLF1081851 (compound 16d) (0-5 μM; 18-20 h) inhibits S1P release with an IC 50 value of 1.93 μM in Hela cells. SLF1081851 (0-30 μM; 20 min) inhibits mSphK1 (recombinant mouse SphK) (10 μM) and mSphK2 (5 μM) in a dose-dependent manner and suggests at least 15-fold selectivity (SphK1 IC 50 ≥30 μM; SphK2 IC 50 ≈30 μM). MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo SLF1081851 (20 mg/kg; i.p., 4 h postdose) significantly inhibits circulating lymphocytes and plasma S1P, and recapitulates the genetic phenotype of Spns2 mice . MCE has not independently confirmed the accuracy of these methods. They are for reference only. Animal Model: C57BL/6 mice Dosage: 20 mg/kg Administration: Intraperitoneal injection; blood was drawn 4 h postdose Result: Significantly decreased circulating lymphocyte count and plasma S1P concentration. Animal Model: SpragueDawley mice (4-week-old) Dosage: 10 mg/kg Administration: Intraperitoneal injection; single dose; measured at 0, 0.5, 1, 2, 4, 6, and 24 h postdose Result: Reached a maximum concentration of 5 μM in blood at 2 h with drug levels sustained at ≥ 2 μM for at least 24 h, proved a half-life of over 8 h in rats. The appearance of SPNS2-IN-1 in circulation correlated with a maximal decrease in lymphocyte count at 4 h (25% lower compared to time =0). Form:Solid IC50& Target:Spns2 (spinster homologue 2)