Inhibit phosphorylation of Syk kinase and subsequent downstream signaling pathways with piceatannol (Piotrowska et al.). Piceatannol is a phenol antioxidant found in grapes, passion fruit, white tea, and Japanese knotweed (Piotrowska et al.). Besides antioxidative effects, piceatannol demonstrates anti-proliferative, anti-inflammatory, and cardioprotective properties (Rotondo et al.). Piceatannol binds with Syk (IC50 = 10 μM; Dash), a tyrosine kinase that coordinates immune-recognition receptors and downstream signaling pathways in various hematopoietic cells such as B cells, mast cells, platelets, and macrophages (Oliver et al.). In addition, it has shown to be able to activate sirtuin 1 (SIRT1) (Howitz et al.), SIRT2 (Gracia et al.), and SIRT5 while inhibiting SIRT3 (Gertz et al.), and has been reported to induce immunomodulatory effects in a variety of immune cells (Kim et al.).

Piceatannol has been used for:

DIFFERENTIATION
· Stimulates osteoblast differentiation potentially via BMP-2 in MG-63 and hFOB cells (Chang et al.).
· Increases the number of astrocytes in neural stem cell cultures undergoing astrocytic differentiation (Arai et al.).
IMMUNOLOGY
· Inhibits release of histamine in mast cells (Oliver et al.).
· Inhibits TNF-induced NF-κB activation and NF-κB-mediated gene expression in myeloid, lymphocyte, and epithelial cells (Ashikawa et al.).
· Blocks NF-κB activation induced by LPS, PMA, ceramide, okadaic acid, and H2O2 in myeloid (KBM-5) cells (Ashikawa et al.).
CANCER RESEARCH
· Induces cell death in BJAB Burkitt-like lymphoma cells by activating caspase-3 and mitochondrial permeability (Wieder et al.).
· Inhibits DU145 and PC-3 cells proliferation by inducing apoptosis through the reduction of poly (ADP-ribose) polymerase (PARP) expression, cleavage of caspase 3, and apoptosis inducing factor AIF, and an increase in cytochrome c (Hsieh et al.).
· Recently shown to possess senotherapeutic-like activity. Reduces the number of senescent mesenchymal stromal cells after genotoxic stress and in senescent replicative cultures (Alessio et al.).
· Inhibits iNOS expression in dextran sulfate sodium-induced models of mouse colitis (Youn et al.).