Diterpenoid alkaloids from the Chinese traditional herbal "Fuzi" and their cytotoxic activity.

Ten diterpenoid alkaloids, including eight aconitine-type C₁₉-diterpenoid alkaloids and two hetisine-type C₂₀-diterpenoid alkaloids, were isolated from the secondary roots of Aconitum carmichaeli Debx., known as "Fuzi" in Chinese traditional herbal medicine. Their structures were established on the basis of their spectroscopic data and comparison with those of the literature. Among these alkaloids, chasmanine, oxonitine and 15-acetylsongoramine were isolated for the first time from this medicinal plant. The cytotoxic activity of the alkaloids were tested against several cell lines by the MTT method in which aconitine, hypaconitine, mesaconitne and oxonitine were found to strongly inhibit the growth of the HePG2 cell line, which showed that the existence and quantity of the ester groups have a significant influence on the cytotoxicity of the diterpenoid alkaloids.