ER-27319

ER-27319, an acridone derivative, is a potent and selective SYK inhibitor, and inhibits the tyrosine phosphorylation of SYK and its activity. ER-27319 inhibits the release of antigen-induced allergic mediators from human and rat mast cells with an IC50 of 10 μM and can be used for study in allergic diseases.

ER-27319 (24 h) inhibits antigen-induced generation of inositol phosphates, release of arachidonic acid, and secretion of histamine and tumor necrosis factor α in RBL-2H3 cells, rat peritoneal and human cultured mast cells, and with IC₅₀ value of 10 μM, approximately^[1].
ER-27319 (10-30 μM, 10 min) selectivity inhibits the tyrosine phosphorylation of SYK induced by the phosphorylated immunoreceptor tyrosine-based activation motif of the FcεRI γ in RBL-2H3 cells^[1].
ER-27319 (up to 100 μM, 60 min) does not inhibit the the tyrosine phosphorylation of ZAP-70 in response to anti-CD3 stimulation in the Jurkat cells^[1].
ER-27319 (100 μM, 10 min) inhibits the tyrosine phosphorylation of two proteins (38, 70 kD) and decreases the tyrosine phosphorylation of the other two proteins (62, 80 kD) in anti-IgG stimulation Canine cutaneous mastocytoma-derived cells^[2].

References:
[1]. Katsuhiro Moriya, et al. ER-27319, an acridone-related compound, inhibits release of antigen-induced allergic mediators from mast cells by selective inhibition of Fcɛ receptor I-mediated activation of Syk. Proc Natl Acad Sci U S A. 1997 Nov 11; 94(23): 12539–12544.
[2]. Yoshitaka Sato, et al. IgG-mediated signal transduction in canine mastocytoma-derived cells. Int Arch Allergy Immunol. 2002 Dec;129(4):305-13.