Diterpenoid alkaloids from the whole herb of Delphinium grandiflorum L

Seven previously undescribed diterpenoid alkaloids, eight reaction products and thirteen known compounds were isolated from the whole plant of Delphinium grandiflorum L. (Ranunculaceae). Grandiflonines A and B have an unprecedented C 20 –diterpenoid alkaloid skeleton, which features inversion of the configuration of C–18. Their structures were determined by comprehensive analyses of spectroscopic data, X–ray diffraction and Mosher's method. The probable biosynthetic pathway of grandiflonine A was discussed. Additionally, the analgesic activity and anti–inflammatory activity by inhibition of NO production were evaluated. Among them, deoxylappaconitine (ED 50 = 0.35 mg/kg, TI = 46.22) showed significant analgesic activity that was superior to the reference drug lappaconitine (ED 50 = 3.5 mg/kg, TI = 3.34). • Seven undescribed diterpenoid alkaloids, eight reaction products and thirteen known compounds were isolated from Delphinium grandiflorum L. • Grandiflonines A and B have an unprecedented C 20 –diterpenoid alkaloid skeleton. • Deoxylappaconitine (ED 50 = 0.35 mg/kg, TI = 46.22) showed a significant analgesic activity superior to the reference drug lappaconitine.