New diterpenoid alkaloids from Aconitum coreanum and their anti-arrhythmic effects on cardiac sodium current.

Two new diterpenoid alkaloids, Guan-Fu base J (GFJ, 1) and Guan-Fu base N (GFN, 2) along with nineteen known alkaloids (3-21) were isolated from the roots of Aconitum coreanum (Lèvl.) Rapaics, which is the raw material of a new approval anti-arrhythmia drug "Acehytisine Hydrochloride". The structures of isolated compounds were established by means of 1D, 2D NMR spectroscopic and chemical methods. All isolates obtained in the present study were evaluated for their inhibitory effects on blocking the ventricular specific sodium current using a whole-cell patch voltage-clamp technique. Among these 21 compounds, Guan-Fu base S (GFS, 3) showed the strongest inhibitory effect with an IC50 value of 3.48 μM, and only hetisine-type C20 diterpenoid alkaloids showed promising IC50 values for further development.