[CAS NO. 343-27-1]  Harmine hydrochloride

Harmine inhibits substrate phosphorylation by DYRK1A more potently than it inhibits substrate phosphorylation by the closely related kinase DYRK1B [half maximal inhibitory concentrations (IC50) of 33 nM versus 166 nM, respectively] and by the more distant members of the family, DYRK2 and DYRK4 (1.9 μM and 80 μM, respectively). Much higher concentrations of harmine are required to suppress tyrosine autophosphorylation of the translational intermediate of DYRK1A in a bacterial in vitro translation system (IC50 = 1.9 μM). Harmine inhibits the phosphorylation of a specific substrate by DYRK1A in cultured cells with a potency similar to that observed in vitro (IC50=48 nM), without negative effects on the viability of the cells. Harmine does not inhibit tyrosine autophosphorylation of DYRK1A in HEK293 cells. Harmine is able to induce beta cell proliferation, increase islet mass and improve glycemic control. It is a CNS stimulant.