Isolation and characterization of a new diterpenoid alkaloid from Delphinium ceratophorum

Extensive phytochemical investigation on the whole herbs of Delphinium ceratophorum (Franch) led to the identification of seven diterpenoid alkaloids including a rare kusnezoline-type C₂₀-diterpenoid alkaloid, ceratophortine A (1), together with six previously identified compounds (2-7). Up to now, only two kusnezoline-type diterpenoid alkaloids were identified as natural products before this research. The structures of all compounds were elucidated by an integrated analysis of HR-ESI-MS, 1D/2D NMR, and X-ray crystallographic data. The analgesic activities of some compounds were evaluated, browniine (7) exhibited significant analgesic activity, showing a writhing inhibition rate of 48.53% at the dosage of 5 mg/kg.