TrkB antagonists

K252a is an alkaloid isolated from Nocardiopsis bacteria. This staurosporine analog is a highly potent cell permeable inhibitor of CaM kinase and phosphorylase kinase (IC50 = 1.8 and 1.7 nmol/L, respectively). At higher concentrations it is also an efficient inhibitor of serine/threonine protein kinases (IC50 of 10 to 30 nmol/L).

Gossypetin, also known as '''3,5,7,8,3',4'-hexahydroxyflavone', is a flavonol, a type of flavonoid. It has been isolated from the flowers and the calyx of Hibiscus sabdariffa'' (roselle) and exhibits a strong antibacterial activity. The compound has also been found to act as an antagonist of TrkB. Gossypetin has radioprotective activity.