Antinociceptive C19-diterpenoid alkaloids isolated from Aconitum pseudostapfianum.

Phytochemical investigation on the roots of Aconitum pseudostapfianum resulted in the isolation of three new aconitine-type C19-diterpenoid alkaloids, pseudostapines A-C (1-3). Their structures were determined by spectral methods such as 1D and 2D (1H-1H COSY, HMQC, NOESY and HMBC) NMR spectroscopy, in addition to high resolution mass spectrometry. The isolated alkaloids were tested in vivo for their antinociceptive potential. As a result, pseudostapine C (3) showed 2-fold more potent antinociceptive effect (ID50 = 60.3 µmol/kg) than the positive control drugs aspirin and acetaminophen.