CHEMBL5735436

In Vitro Binding Assay: Newly synthesized compounds were first evaluated for binding potency toward S1P1 by a [32P]S1P competitive binding assay following published procedure (J. Rosenberg, H. Liu, Z. Tu, A practical process for the preparation of [32P]S1P and binding assay for S1P receptor ligands, Appl. Radiat. Isot. 102 (2015) 5-9), and using S1P as a reference compound. [32P]S1P was first prepared by incubating sphingosine and [γ-32P]ATP with sphingosine kinase 1 as previously reported (J. Rosenberg, H. Liu, Z. Tu, A practical process for the preparation of [32P]S1P and binding assay for S1P receptor ligands, Appl. Radiat. Isot. 102 (2015) 5-9). [32P]S1P was dissolved in DMSO, and then diluted in the assay buffer (50 mM HEPES-Na with 5 mM MgCl2, 1 mM CaCl2, and 0.5% fatty acid-free bovine serum albumin, pH=7.5). Compounds were dissolved in DMSO and diluted to different concentrations with assay buffer, followed by adding commercial cell membranes expressing recombinant human S1P receptors (1, 2, 3, 4, and 5) in the assay buffer at room temperature in 96-well plate. [32P]S1P solution was then added to give a final volume of 150 μL containing 0.1 nM of [32P]S1P and 1 μg of membrane protein per well. Competitive binding was performed for 60 min at room temperature and terminated by collecting the membranes onto 96-well glass fiber (GF/B) filtration plates (Millipore, Billerica, Mass.). Each filter was washed with 200 μL of assay buffer for five times. The filter bound radionuclide was measured by a Beckman LS3801 scintillation counter using Cherenkov counting. The reported IC50 values were calculated using the 4 parameter equation, least-square non-linear regression curve-fit, with GraphPad Prism software (GraphPad Software, Inc). Each assay was repeated at least three times with duplicate wells for each compound; the reported values (mean±SD, nM) are calculated from the average of all assays. Assays for compounds which showed no activity (IC50>1000 nM) were only repeated twice.