Huperphlegmines A and B, two novel Lycopodium alkaloids with an unprecedented skeleton from Huperzia phlegmaria, and their acetylcholinesterase inhibitory activities.

Two novel Lycopodium alkaloids, huperphlegmines A and B (1 and 2), were isolated from the aerial parts of Huperzia phlegmaria collected in Vietnam, together with the five known compounds lycophlegmariol A (3), phlegmariurine B (4), 5-hydroxymethyl-2-furaldehyde (5), rhemanone C (6), and loliolide (7). The chemical structures of the present compounds were elucidated by means of 1D and 2D NMR and HRESIMS spectroscopy, and by comparisons to the reported data in the literature. Compounds 1 and 2 showed moderate acetylcholinesterase inhibitory activities, with IC50 values of 25.95 ±â€¯0.67 and 29.14 ±â€¯0.77 µg/mL, respectively.