Lycodine-Type Lycopodium Alkaloids from the Whole Plants of Huperzia serrata

ABSTRACT: Three new lycodine-type Lycopodium alkaloids, namely 1-methyllycodine (1), 8α-hydroxy-15,16-dehydro-des-N-methyl-α-obscurine (2), N-methyl-16-hydroxyhuperzine B (3), and one new natural lycodine-type Lycopodium alkaloid, N-methylhuperzine A (4), along with 11 known analogues (5–15), were isolated from the whole plants of club moss Huperzia serrata. The structures of 1–4 were elucidated on the basis of NMR spectroscopic and mass spectrometry data. Among them, compound 1 was the first lycodine-type alkaloid possessing a methyl group at C-1. In addition, the structure of 5 was confirmed by the single-crystal X-ray crystallography data and its (13)C NMR was reported for the first time in current study. Compounds 1–5 were tested their BACE1 inhibitory activity. GRAPHICAL ABSTRACT: [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s13659-017-0140-z) contains supplementary material, which is available to authorized users.