W146 A85390 (Previously 857390) (R)-3-Amino-(3-hexylphenylamino)-4-oxobutylphosphonic acid (TFA salt)

Compound 2a is a selective antagonist for human S1P₁ (hS1P₁) receptor activation by the physiological agonist S1P. (a) Structures of 2a and 2b. (b) Shift in EC50 for S1P activation of hS1P₁ receptor by 2a and 2b. We tested CHO cell membranes expressing stably transfected hS1P₁ receptors for antagonism in a GTP-gS binding assay. Activation of hS1P₁ receptors by 1 alone (closed squares) or in the presence of 10 mM 2a (inverted triangles) and 2b (circles) is expressed normalized to percentage GTP-gS binding induced at maximal S1P concentration. The EC50 value was 0.8 nM for 1 alone; it was 398 nM and 50 nM in the presence of 2a and 2b, respectively. (c) We derived Ki values for S1P activation of the hS1P₁ receptor from antagonist competition curves; they were 77 nM for 2a (inverted triangles) and 4.63 mM for 2b (circles).