R112 is an ATP-competitive inhibitor of Syk kinase with a Ki of 96 nM. R112 inhibits Syk kinase activity with an IC50 of 226 nM. IC50 value: 226 nM [1]Target: Sykin vitro: R112 blocks leukotriene C4 production and all proinflammatory cytokines tested. Its onset of action was immediate, and the inhibition was reversible. R112 is able to completely inhibit all three IgE-induced mast cell functions: degranulation, lipid mediator production, and cytokine production. R112 potently, completely, and rapidly abrogated all mast cell activation cascades triggered by IgE receptor cross-linking.[1]
[1]. Rossi AB, et al. Identification of the Syk kinase inhibitor R112 by a human mast cell screen. J Allergy Clin Immunol. 2006 Sep;118(3):749-755. [2]. Meltzer EO, et al. An intranasal Syk-kinase inhibitor (R112) improves the symptoms of seasonal allergic rhinitis in a park environment. J Allergy Clin Immunol. 2005 Apr;115(4):791-796.