Six new Lycopodium alkaloids, named lycophlegmarinines A-F (1-6), were isolated from whole plants of Phlegmariurus phlegmaria. Their structures were determined based on spectroscopic data analysis, quantum-chemical NMR calculations, and single-crystal X-ray crystallography. Lycophlegmarinine A (1) possesses a novel C15N skeleton with a 9/5/5 ring system, and its plausible biosynthetic pathway is proposed. Compounds 2 and 3 showed inhibitory activity against acetylcholinesterase, with IC50 values of 6.9 mu M and 35.2 mu M, respectively.(c) 2022 Elsevier Ltd. All rights reserved.