Piceatannol is a stilbenol that is trans-stilbene in which one of the phenyl groups is substituted by hydroxy groups at positions 3 and 4, while the other phenyl group is substituted by hydroxy groups at positions 3 and 5. It has a role as a geroprotector, a hypoglycemic agent, an antineoplastic agent, a protein kinase inhibitor, a tyrosine kinase inhibitor, an apoptosis inducer and a plant metabolite. It is a polyphenol, a member of catechols, a member of resorcinols and a stilbenol. Piceatannol has antitumor, antioxidant, and anti-inflammatory activities, it also has the potential to control obesity. Piceatannol inhibits effector T cell functions by suppressing TcR signaling.