Antinociceptive C19–diterpenoid alkaloids from the roots of Aconitum nagarum

Three new C19–diterpenoid alkaloids, nagarumines A–C (1–3), together two known alkaloids, deoxyaconitine (4) and N-deethyldeoxyaconitine (5), were isolated from the roots of Aconitum nagarum. The structures of the new compounds were elucidated by spectral methods such as 1D and 2D (1H-1H COSY, HMQC, and HMBC) NMR spectroscopy, as well as high resolution mass spectrometry. The in vivo pharmacological studies revealed that nagarumine C (3) possessed comparable antinociceptive activity (ED50 = 76.0 μmol/kg) with the positive control drugs aspirin and acetaminophen.