Two unique C21-diterpenoid alkaloids from Aconitum carmichaelii

Two sulfonated diterpenoid alkaloids possessing different but related novel carbon skeletons, named aconidenusulfonine A (1) and 12,16-secoaconidenusulfonine A (2), respectively, were isolated as minor components from an aqueous extract of the lateral roots of Aconitum carmichaelii (“Fu Zi”). The structures of 1 and 2, representing the first two C₂₁-diterpenoid alkaloids from nature, were determined by analysis of various spectroscopic data and chemical transformation, of which 1 was further proved by single-crystal X-ray diffraction. Especially, 1 exhibited dose-depended analgesic activity consistent with the clinical function of Fu Zi.