Two sulfonated seco C-20-diterpenoid alkaloids, aconapelsulfonines A (1) and B (2), were isolated from an aqueous extract of the raw material of Fu Zi (the Aconitum carmichaelii lateral roots), of which the structures were elucidated by various spectroscopic data, combined with X-ray crystallographic analysis. The unprecedented skeletons are biogenetically proposed to be derived via Criegee rearrangements of the napelline-type architecture. The two compounds exhibited dose-depended analgesic activities on an acetic acid-induced mice writhing test. (C) 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.