Fifteen new diterpenoid alkaloids from the roots of Aconitum kirinense Nakai.

Extensive phytochemical investigation from the roots of Aconitum kirinense Nakai led to the identification of fifteen new compounds, including four ranaconitine type C₁₈-diterpenoid alkaloids (kirisines A-D, 1-4), one lappaconitine type C₁₈-diterpenoid alkaloid (kirisine E, 5), seven denudatine type C₂₀-diterpenoid alkaloids (kirisines F-L, 6-12), and three napelline type C₂₀-diterpenoid alkaloids (kirisines M-O, 13-15), together with 25 known ones. Their structures were elucidated by extensive spectroscopic analyses. Among them, compounds 1 and 2 are rare diterpenoid alkaloid with 9,14-methylenedioxy group, and the latter also has a rare chloro-substituent. The diterpenoid alkaloids isolated were C₁₈, C₁₉ and C₂₀-category, which might provide further clues for understanding the chemotaxonomic significance of this plant. The isolated compounds were tested for neuroprotective activity and acetylcholinesterase inhibitory activity. Compounds 7, 18, 30 and 40 which exhibited moderate activity at 80 μM against acetylcholinesterase.