Secoyanhusamine A (1), a rare rearranged seco-isoquinoline alkaloid derived from ring oxidative cleavage, was isolated from an aqueous extract of Corydalis yanhusuo tubers, together with its biosynthetic precursor dehydrocorybulbine (2). Secoyanhusamine A (1) was the first example of a highly oxidized isoquinoline inner salt resulting in a 5-(2-azanylethyl)-2-carboxylate-4-oxo-4H-pyran ring system. The biosynthetic pathway of 1 was also postulated. Secoyanhusamine A (1) exhibited potent inhibition against acetylcholinesterase (AChE) with an IC(50) value of 0.81 +/- 0.13 muM. Molecular simulation docking demonstrated that 1 created a strong interaction with the Asp-74 residue of AChE via attractive charge of the quaternary nitrogen. CI - Copyright (c) 2022 Wang, Xia, Wu, Wang, Lin and Lin.