MRS-1191

MRS-1191 is a potent and selective A₃ adenosine receptor antagonist with a K_B value of 92 nM, a K_i value of 31.4 nM for human A₃ receptor and an IC₅₀ of 120 nM for CHO cells^[1]. MRS-1191 is a click chemistry reagent, itcontains an Alkyne group and can undergo copper-catalyzed azide-alkyne cycloaddition (CuAAc) with molecules containing Azide groups. IC50 & Target: Ki: 31.4 nM (human A₃ adenosine receptor)^[1] In Vitro: The effects of putative A₃ adenosine receptor antagonist of MRS-1191 is characterized in receptor binding and functional assays. MRS-1191 is found to be competitive in saturation binding studies using the agonist radioligand [¹²⁵I]AB-MECA (N⁶-(4-amino-3-iodobenzyl)adenosine-5'-N-methyluronamide) at cloned human brain A₃ receptor expressed in HEK-293 cells. Antagonism is demonstrated in functional assays consisting of agonist-induced inhibition of adenylate cyclase and the stimulation of binding of [³⁵S]guanosine 5'-O-(3-thiotriphosphate) ([³⁵S]GTP-gamma-S) to the associated G-proteins. MRS-1191 with a K_B value of 92 nM, proves to be highly selective for human A₃ receptor vs human A₁ receptor-mediated effects on adenylate cyclase^[1].