Phleghenrines A–D and Neophleghenrine A, Bioactive and Structurally Rigid <i>Lycopodium</i> Alkaloids from <i>Phlegmariurus henryi</i>

Abstract

Five new Lycopodium alkaloids, phleghenrines A-D (1-4) and neophleghenrine A (5), were isolated from Phlegmariurus henryi (Baker) Ching. The structures and absolute configurations of 1-5 were determined using extensive spectroscopic data coupled with computational calculations and revealed 1-4 possess a bicyclo[3.2.2]nonane core, whereas 5 possesses an unprecedented 9-azaprotoadamantane core. Compounds 1 and 4 showed potent acetylcholinesterase (AChE) inhibitory activities, and 4 is a good lead natural product for the treatment of Alzheimer's disease.