A C(20)-diterpenoid alkaloid with an unprecedented carbon skeleton, acoapetaludine A, together with ten undescribed aconitine-type C(19)-diterpenoid alkaloids, acoapetaludines B-K, were isolated from the whole plants of Aconitum apetalum (Huth) B. Fedtsch. (Ranunculaceae). The structures were elucidated based on a comprehensive spectroscopic data analysis. The absolute configuration of acoapetaludine A was determined by quantum ECD calculation. Acoapetaludines D and E exhibited weak anti-Helicobacter pylori activity at a minimum inhibitory concentration (MIC) of 100 and 50鈥痬ug/mL, respectively. CI - Copyright (c) 2019 Elsevier Ltd. All rights reserved.