Abstract:To understand the alkaloidal constituents of Aconitum episcopale, an Aconitum species endemic to China, and their toxicity against rat cardiomyocyte H9c2 cells, ten diterpenoid alkaloids were extracted from its roots. Based on physical and chemical properties and spectral data, their structures were identified as yunaconitine (1), crassicauline A (2), vilmorrianine C (3), vilmorrianine A (4), forestine (5), falconeridine (6), 14-O-acetylsachaconitine (7), sachaconitine (8), chasmanine (9) and vilmotenitine A (10), were isolated and identified from A. episcopale roots. Compounds 5, 6 and 10 were isolated from this species for the first time. The median inhibition concentrations of compounds 1- 4, 6- 7 and 9- 10 on H9c2 cells ranged from 163.8 to 341.6 μg/mL, showing the alkaloids in A. episcopale had toxic effects on H9c2 cells.