Abstract: Diterpenoid alkaloids have neroprotective activity. Herein, three napelline-type diterpenoid alkaloids 1–3, two aconitine-type diterpenoid alkaloids 4–5, and one isoquinline-type alkaloid 6, as well as one lignan glycoside 7, have been isolated from the roots of Aconitum pendulum Busch. Compounds 1 and 7 were new compounds, and their chemical structures were determined on the basis of nuclear magnetic resonance (NMR) spectra and mass spectrometry analysis. A ThT assay revealed that compound 2 showed significant disaggregation potency on the Aβ1−42 aggregates. Graphical Abstract: [Figure not available: see fulltext.]. © 2019, The Author(s).