PiceatannolS3026

Piceatannol displays ~10-fold selectivity for Syk over Lyn. Piceatannol treatment in RBL-2H3 cells strongly inhibits the antigen-stimulated phosphorylation of Syk and of most other cellular proteins but not the receptor β or γ subunit, in a dose-dependent manner. Piceatannol is also a potent inhibitor of histamine release in mast cells. Selective inhibition of Syk by Piceatannol blocks receptor-mediated down-stream cellular responses in mast cells including prevention of 1,4,5-IP₃ synthesis, secretion and membrane ruffling and spreading. ^[1] Piceatannol also potently inhibits PKA, PKC, MLCK, and CDPK with IC50 of 3 μM, 8 μM, 12 μM, and 19 μM, respectively. ^[2] Piceatannol selectively prevents the IFNα-induced tyrosine phosphorylation of STAT3 and -5 but not STAT1 and -2, paralleled by the loss of Jak1 and IFNAR1 tyrosine phosphorylation but not Tyk2 and IFNAR2. ^[3] Piceatannol potently induces apoptotic cell death in BJAB Burkitt-like lymphoma cells with ED50 of 25 μM, through the activation of caspase-3 and mitochondrial permeability transition independent of the CD95/Fas signaling pathway. ^[4] Piceatannol inhibits NF-κB activation induced by TNF, H₂O₂, PMA, LPS, okadaic acid, and ceramide. Piceatannol suppresses the expression of TNF-induced NF-κB-dependent reporter gene and of matrix metalloprotease-9, cyclooxygenase-2, and cyclin D1 independent of Syk kinase, by blocking TNF-induced IκBα phosphorylation, p65 phosphorylation, p65 nuclear translocation, and IκBα kinase activation. ^[5] Piceatannol directly binds with PI3K in an ATP-competitive manner, and suppresses PI3K activity with anti-atherosclerotic effects more effectively than resveratrol. ^[8] Piceatannol inhibits androgen-dependent (AD) and androgen-independent (AI) CaP cell proliferation, which is accompanied by reduced expression of mTOR and its key effectors AKT and eIF4EBP-1. ^[10]